Science G7_ Physics_ Electricity

7/27/2019 Science G7_ Physics_ Electricity

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OHSP ONLINE LESSON TEMPLATE

SCIENCE GRADE 7

MODULE NO. : Physics: Electricity

MODULE INTRODUCTION AND FOCUS QUESTION(S):

During thunderstorms, should we be more afraid of the thunder or thelightning? Why? Have you experienced statics while combing your hair orwhen touching a computers monitor? Did you experience some sort of shock?How can we protect ourselves from electric shock?

Find out the answers to these questions in this module. More importantly,you will learn how to be safe from electric shocks. You will also learn how thescience of charges and charging is being used in making our lives better.

MODULE LESSONS AND COVERAGE:

In this module, you will examine these questions when you take the followinglessons:

Lesson 1 Charges and charging processesWhat are charges? How do bodies become charged?

Lesson 2 Interactions between charged bodiesHow do charged bodies interact with each other?

Lesson 3 Safety with chargesWhat does it mean that some appliances need to be grounded?How does a lightning rod protect us from harm?

Lesson 4 Applications of charges and charging processesHow are these concepts on charges applied in industries and incleaning up the air?

In these lessons, you will learn the following:

Lesson 1 Differentiate the three kinds of charges, in terms of protons andelectrons. Discuss and demonstrate how objects become charged.

Lesson 2 Describe and predict how charged and uncharged bodies interactwith each other.

Lesson 3 Investigate how grounding is implemented in appliances.Discuss how lightning rods keep us safe during storms.

Lesson 4 Investigate and report on how concepts on charges are applied inindustries and in cleaning up the air.


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Here is a simple map of the above lessons you will cover:

To do well in this module, you need to remember and do the following:

1. Open the indicated interactive simulations. Go beyond the given instructionsand questions. Explore further and deeper as your time allows.

2. Open and view the indicated videos. Review the videos as many times asneeded, as you answer the discussion questions related to them.

3. Gather the materials for the experiments and demonstrations and actually dothem yourself. The actual experiments give you a richer learning experiencethan just reading the texts and even watching related videos.

4. Take down notes as you go through the simulations, videos and experiments.Writing on paper or typing on your computer helps you remember andunderstand things easier.

NEXT

Lesson 1:Charges and Charging Processes

Lesson 2:Interactions Between Charged Bodies

Lesson 3:Safety with Charges

Lesson 4:Applications of charges and charging processes


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PRE-ASSESSMENT:Lets find out how much you already know about this module. Click on the letterthat you think best answers the question. Please answer all items. After takingthis short test, you will see your score. Take note of the items that you were not

able to correctly answer and look for the right answer as you go through thismodule.

1. The nucleus charge is ______ because _____.A. neutral ; it has equal numbers of positive and negative chargesB. neutral ; all charges are outside the nucleusC. positive ; it has positively charged protons and uncharged neutrons *D. negative ; it has more electrons than protons

The nucleus is positive because it has protons in it. The negativelycharged electrons are outside the nucleus.

2. A sodium ion, Na+ has a net charge of +1 because ______.A. it has only one protonB. it has one less electron than protons *C. it has one less proton than electronsD. it gained one more proton from another atom

A sodium atom has 11 protons in its nucleus and 11 electrons outside. Iteasily gives off its one outermost electron, and so it has one less electronthan protons, becoming a Na

+ion.

3. If a neutral metal sphere (X) is placed in contact with a positively chargedmetal sphere (Y), sphere X will _____.

A. remain neutralB. become positively charged as well *C. become negatively chargedD. fluctuate from being positively charged and negatively charged

The positively charged sphere (deficient of electrons) will take someelectrons from the initially neutral sphere. This will make the initiallyneutral sphere also deficient in electrons and therefore positively charged.

4. In charging by induction, a charged body (X) is placed near to a neutral body(Y) that is to be charged. If X is negatively charged and Y is connected to theground, Y will _____.

A. remain neutralB. become positively charged *

XY XY XY


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6. Which of the following most needs to be grounded?

A. flat ironB. laptop

C. TVD. washing machine *

The pulsator in the wash tub gets turned by themotor through a rubber belt. The occasional rubbingbetween the metal and the rubber belt causeselectrostatic charging. The charge build-up couldgive the user an electric shock. Grounding thewashing machine prevents charge from building up.

7. Lightning rods are placed _____ of a building.A. at the baseB. above the windowsC. above the highest pointD. on all the corners of the rooftop

Placing rods above the highest points of a building will ensure that if everlightning strikes, it hits the lightning rod, and not any other part of thebuilding.

8. A lightning rod works by _______.

A. conducting the charge to the ground, through the buildingB. conducting the charge to the ground, bypassing the building *C. collecting the charge into a storage device, for use later as electricity

The charge from lightning is immediately conducted down into the ground,bypassing the building, keeping the people inside the building unharmed.If the lightning rod is not grounded, then electricity will pass through thebuilding and the people in it will not be safe. The great amount of chargecannot be stored (yet) for later use as electricity.


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9. A single electrons charge is 1.6 x 10-19 Coulomb. How will an initiallyneutral body be made to have a charge of1.0 microCoulomb?

A. have it gain 6.3 X 1012 electrons *B. remove 6.3 X 1012 electrons from it

C. have it gain 1.6 X 10

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electronsD. remove 1.6 X 1013 electrons from it

Q = n qe where Q is the charge developedn is the number of electronsqe is the charge of an electron

n = Q / qe = ( - 1.0 x 10-6

Coulomb) / 1.6 x 10-19

Coulomb per electonn = 6.3 X 1012 electrons

This number of electrons will have to be gained by an initially neutral body

for it to have a 1.0 microCoulomb charge.

For items 10 and 11, refer to the triboelectric series in the box at the right:

10. What charges will be acquired by PVC and woolrubbed with each other?

A. PVC: positive; wool: negativeB. PVC: negative; wool: positive *C. both will have positive charges

D. both will have negative charges

The PVC will gain electrons from the wool.

11. Which rubbing material will create the most charge on a glass rod?

A. furB. human hairC. silk *D. wool

From among the choices, silk is lowest in the series, thus having thegreatest tendency to gain electrons. The more electrons drawn out fromthe glass rod, the greater the charge created in it.

leatherglass

human hairwoolfursilk

rubberstyrofoampolyvinylchloride

(PVC)

Increasingtendencyto gainelectrons


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12. The picture at the right shows a green wireattached to the motor at the underside of awashing machines wash tub. To where does theother end of this wire connect to?

A. to the motor of the spinner tubB. to the water pipes outside *C. to the dial-switch-timerD. to the plug

The green wire is a grounding wire. Its otherend should be connected to the water pipeoutside the machine. This way, charge isprevented from building up in the washingmachine.

13. What could happen if this wire is not firmlyconnected at either ends?

A. The motor for the wash tub will run, but that for the spin dryer will not.B. The washing machine will not run.C. The motor will keep running even as the timer goes down to zero.D. The person using the machine might get an electric shock. *

If the grounding wire is not connected, then the charge that mayaccumulate in the machine may cause an electric shock on the personusing it.

14. Why would it be dangerous for people to be out in the open fields duringheavy rains and thunderstorms?

A. They might get struck by lightning. *B. They might get sick with colds and flu.C. They might get stranded in the ensuing flood.D. They might get carried away by the strong winds.

People in open fields (with no trees or houses) are at risk of getting struckby lightning. The other risks above should also be avoided, but the mostfatal of them is the first.


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16. You conducted a magic show with thekids in an orphanage you visited. Youshowed them the demonstration wheretissue bits flew up to the plastic sheet.How would you best explain to the kids

why the tissue bits moved up, defyinggravity? Assume the plastic sheet to benegatively charged.

A. The tissue bits are neutral, and so it was attracted by the chargedplastic sheet.

B. While on the table, the tissue bits got induced to have a positivecharge.

C. While on the table, the tissue bits got polarized with its upper sidepositively charged. *

D. The plastic sheet induced a positive charge on the table top, and this

repelled the tissue bits.

The negatively charged plastic sheet repels the electrons in the tissue bits,pushing them lower. This polarizes the tissue bits, with the upper sidepositively charged, and the lower side negatively charged. The tissue bitshowever are still electrically neutral. (Left figure below)

With the tissue bits now polarized, the upper side gets attracted to theplastic sheet. The attraction overcomes the repulsion that the lower sideexperiences. (Right figure below)

Table top

Plastic

sheet

-- -

-

-

+ + +++

--

--

--

- -

-

+

--

--

--

- -


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17. You then touched the top side of the plastic sheet where there are tissue bitsunder it. What would have happened, and why?

A. The tissue bits stay attached to the

bottom of the plastic sheet. Yourfinger has no effect on the charges inthe objects.

B. The tip of your fingers also gotpolarized to have a partial positivecharge, and your finger repels thetissue bits.

C. Your fingertip grounds the plastic, soit becomes neutral and thus no longerattracting the tissue bits. *

D. Your fingertip makes the plastic have

a positive charge, and so it then repels the tissue bits.

Touching the plastic sheet grounds the plastic, at least the point touched.This point becomes neutral, and so no longer able to attract the tissue bit.Option B is not possible, as your hand is connected to your body, and isconnected to the ground. The small plastic sheet can polarize a smallerobject, but not a bigger body that is connected to the ground.Option D is not possible. There is no way for the finger to cause theplastic sheet to have a positive charge. The finger can take away justenough electrons to make it neutral, but not to make it positively charged.

Table top

Plasticsheet


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19. Consider the boy at the left sideof the picture. How would thehazard he is exposed to beeliminated?

A. The trees branches near thepower lines should betrimmed. *

B. The sign No climbing shouldbe nailed onto the tree.

C. A playground should be builton the open area.

D. He is not exposed to anyhazard. As long as he doesnttouch the power lines, hell be alright.

If the branches touch the power lines, the boy is at risk of gettingelectrocuted, especially when it rains.

20. If you are the safety engineer in the town where this picture was taken, whatwould you do? Write below concrete actions to make this area of your townsafer.

________________________________________________________

________________________________________________________

________________________________________________________

________________________________________________________

________________________________________________________

________________________________________________________

Safety signs could be placed at the grounds near the power lines: Noflying of kites.

Remind residents to not let electrical wires and appliances near bodies ofwater like in kiddie pools.

Trim the trees near the power lines. Do not let branches grow near thepower lines.

NEXT


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Lesson 1Charges and Charging processes

In this lesson, you shall:

Differentiate the three kinds of charges, in terms of protons and

electrons. Discuss and demonstrate how objects become charged.

EXPLORE:

In this lesson, we will focus on the following questions: What are charges? Howdo bodies become charged?

1.Pre-reading check. Before plunging into our first lesson, answer thefollowing questions. Click on your answer.

a. The fundamental carriers of negative charge:A. atomsB. electrons *C. neutronsD. protons

b. The protons charge is _____.A. +1 CoulombB. 1 CoulombC. + 1.6 x 10-19 Coulomb *D. 1.6 x 10-19 Coulomb

c. A neutral atom _____.A. has no electronsB. has only neutrons in its nucleusC. has equal numbers of protons and neutronsD. has equal numbers of protons and electrons *

d. An atom becomes a positive ion when it _____.A. gains one or some electronsB. loses one or some electrons *C. gains one or more protons

D. loses one or more protons

e. An atom becomes a negative ion when it _____.A. gains one or some electrons *B. loses one or some electronsC. gains one or more protonsD. loses one or more protons


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1.2 Webpage reading: Atomic Structure

Did you get all the correct answers?

Review the items where you had mistakes. Keep them in mind as you read thewebpage on atomic structure: http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm

Open the page below to know more about electrons:http://www.windows2universe.org/physical_science/physics/atom_particle/electron.html

Click on the link to protons to go to another page, or open this:http://www.windows2universe.org/physical_science/physics/atom_particle/proton.html

Do you now understand how atoms become charged? Sub-atomic particles are charged,and so atoms are either positive negative or neutral, depending on the numbers of

protons and electrons in them.

1.3 Comprehension Check: How atoms get charged

To summarize the key ideas from the readings, complete the statements belowby clicking and dragging in the correct tiles from below.

1. The particles whose charge is 1.6 x 10-

Coulomb: _____.

2. The particles whose charge is + 1.6 x 10- Coulomb: _____.

3. The uncharged particles are the _____.

4. When an atom loses electrons, it becomes _____.

5. When an atom gains electrons, it becomes _____.

6. To become charged, atoms can easily gain or lose _____, but not _____.

protons

electrons

neutrons neutral

positively chargednegatively charged

electrons

protons

neutrons

neutral

negatively charged

electrons protons
http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htmhttp://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htmhttp://www.windows2universe.org/physical_science/physics/atom_particle/electron.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/electron.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/electron.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/proton.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/proton.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/proton.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/proton.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/proton.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/electron.htmlhttp://www.windows2universe.org/physical_science/physics/atom_particle/electron.htmlhttp://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm


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1.4 Rubbing BalloonsAfter learning how atoms become charged, lets now see how objects becomecharged.

a. Get two rubber balloons. Inflate them. Hang them on strings, about 1foot long.

b. Rub the balloons on your shirt, blouse, pants, or table cloth.c. Pass the balloon above your forearm. How does it feel? Place itabove your head. What happens?

d. Hold the strings together on one hand. Do the balloons repel eachother?

e. Tear up a piece of tissue paper into small bits. Hold the rubbed balloona few inches above the tissue bits. What happens?

f. Hold the rubbed balloon against the wall. What happens?

(You may have to rub the balloons again after some time through theprocedures above.)

Why is it that rubbing the balloons makes them do some gravity-defying tricks?

1.5 Rubbing Balloons Worksheet

In this worksheet, you will record your observations in the previousactivity. Write also in the 3rdcolumn your guess-planations (guess-explanations) for each observation.

Procedure / Set-up Observations Guess-planations

Rubbed balloon placednear forearm

Rubbed balloon placednear ones head

Two rubber balloons,each hung down by theirthreads

Rubbed balloon placednear tissue bits

Rubbed balloon broughtnear the wall

Review your Observations and Guess-planations. What do you notice about youranswers? What comments are similar? What comments are different? Can yousee any pattern to the results that you got? What do you think is a principle at workin these different procedures? Remember that only electrons (and not the protons)can be passed between bodies through ordinary interactions like rubbing andcontact. Review your answers, with this key fact in mind.


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End o f EXPLORE:

You just tried finding out about charges and how objects become charged. You

also gave your initial ideas on why charged objects behave as observed. Letsnow find out more about charges by doing the next activities.NEXT

FIRM UP:Your goal in this section is to learn and understand some key concepts, byworking on the following questions:

How do we know what charges objects acquire when they arerubbed together? Which becomes positive? Which becomesnegative?

What is the triboelectric series? How was it made or determined?

1.6 Web page reading: Creating Charges with Friction - Triboelectricity

a. Write down your initial answers to these questions:

How do we know which of the two objects rubbed togetherbecomes positively charged?

Which becomes negatively charged?

What pairs of objects will more likely create strong charges in theobjects?

b. Open and read this web page:http://regentsprep.org/Regents/physics/phys03/atribo/default.htm

1.7 Triboelectricity: Check for Understanding

Lets review the ideas found in the Website you just read. Click on youranswers to the following questions.

1. Which should your rub with amber to make it positively charged?A. furB. leatherC. styrofoam *D. wool
http://regentsprep.org/Regents/physics/phys03/atribo/default.htmhttp://regentsprep.org/Regents/physics/phys03/atribo/default.htmhttp://regentsprep.org/Regents/physics/phys03/atribo/default.htm


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2. Which material, when rubbed with Styrofoam will create thestrongest negative charge on Styrofoam?

A. leather*B. PVCC. Teflon

D. wool

3. When you rub an inflated balloon with your hair, the balloon______, your hair _____.A. becomes negatively charged ; stays neutralB. becomes positively charged ; stays neutralC. becomes positively charged ; becomes negatively chargedD. becomes negatively charged ; becomes positively charged *

4. Which pairs of materials, when rubbed together, will cause theweakest net charge in them?

A. silk and wood *B. glass and rubberC. scotch tape and PVCD. dry hands and Teflon

5. Which of the following statements most correctly describe the signof the charge that objects acquire by rubbing?

A. Some objects can become only positively charged, while otherobjects can become only negatively charged.

B. Objects can become either positively or negatively charged,depending on the material used to rub them. *

C. Soft objects tend to become positively charged, while hardobjects tend to become negatively charged.

D. Natural materials tend to become positively charged, whilesynthetic materials tend to become negatively charged.

How did you do with this quiz? If you did well, continue to the next part. If not, goback and find out from the reading the reason for the correct answers.

End of FIRM UP:

In this section, you have read about how objects become charged eitherpositively or negatively.

Go back to the previous section and compare your initial ideas with thediscussion in the assigned webpage. How much of your initial ideas are found inthe discussion? Which ideas are different and need revision?

Now that you knowthe important ideas about this topic, lets go deeper bymoving on to the next section.


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NEXT

DEEPEN:

Your goal in this section is to take a closer look at some aspects of the topic.

Here you will see some demonstrations on how real charged objects interact.From their interactions and from your prior readings, you will decide on thecharges of these objects.

1.8 Video Analysis: Rotating Straw

Open this video: http://www.youtube.com/watch?v=Ne7oqESE5Zw

Re-view the video, pausing it every now and then so you can take down notes.When done, answer the following questions.

Video Analysis Worksheet: Whats my charge?

As you review the video, fill in the table below.

Material rubbed with Interaction withrotating straw(attracted or

repelled)

The objects are thereforecharged (+ or -)

How did you decide on the charges of the objects? Did you actually see whetherobjects are in excess or deficient of electrons? Or did you have to rely on theobserved interactions and the triboelectric series? Explain.

1.9 Positive or Negative?
http://www.youtube.com/watch?v=Ne7oqESE5Zwhttp://www.youtube.com/watch?v=Ne7oqESE5Zwhttp://www.youtube.com/watch?v=Ne7oqESE5Zw


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Review the triboelectric series in this page:

http://regentsprep.org/Regents/physics/phys03/atribo/default.htm

Gather as much materials in the list that you can gather. Choose different pairsof objects to rub together. If you have access to an airconditioned room (low

humidity), perform this activity there. Humidity will cause the rubbed objects tomore quickly discharge, thus the effects will not be observable.

Determine the charges of the rubbed objects by seeing how they affect either acharged straw that is free to rotate (like in the video) or a charged strip of plasticcover that is hung and free to swing towards or away an object placed near it.(e.g. If the object repels the negatively charged plastic strip, then it is alsonegative. If the strip is attracted, then the object is positively charged.)

Fill the table below:

Pair ofobjectsrubbed

Charges of theobjects, aspredicted usingthe triboelectricseries

Effect on thestraw or plasticstrip (attract orrepel)

Charge of theobjects, based oninteraction withstraw or strip

1

2

3

4

5

Did the objects behave as predicted by the triboelectric series? Or were thereany discrepancies? What could have caused these discrepancies? Go back tothe reading on the triboelectric series as you review your ideas.

End o f DEEPEN:
http://regentsprep.org/Regents/physics/phys03/atribo/default.htmhttp://regentsprep.org/Regents/physics/phys03/atribo/default.htmhttp://regentsprep.org/Regents/physics/phys03/atribo/default.htm


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In this section, you saw demonstrations on how charged objects interact witheach other. You then inferred the charges of these objects from the observedinteractions.

What new realizations do you have about the topic? What new connections have

you made for yourself?

Now that you have a deeper understanding of the topic, you are ready to do thetasks in the next section.

NEXT

TRANSFER:Your goal in this section is apply your learning to real life situations. You will begiven a practical task which will demonstrate your understanding.

1.9 Make your own demo!

Explore other related videos on electrostatic interactions in You Tube.

See which demonstrations you can do yourself.

Can you come up with your new demonstrations with materials that are availableto you? Try to come up with demonstrations that are:

interesting especially for kids

replicable (even by kids) and safe effective for teaching others about charges

Maybe you will want to video your demonstrations and upload them to You Tubeand be the next You Tube discovery!

End o f TRANSFER:

In this section, your task was to create your own demonstration on electrostaticcharging. This performance task is just a practice and preparation for the moreexciting and relevant performance tasks in the next lessons.

How did you find the performance task? How did this task help you furtherunderstand the science of charges and the interactions between chargedbodies? Write down your reflections on your notebook or on a journal file in yourcomputer.

You have completed this lesson. Before you go to the next lesson, you have toanswer the following post-assessment. If you pass this test, you may move on to


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the next lesson. If you do not pass this test, you may go back and review thelesson and take this test again.

NEXT

CHECK-UP TEST:

1. The fundamental charges in nature are the _____ and the _____.A. protons ; electronsB. electrons ; neutronsC. atoms ; protonsD. neutrons ; protons

2. Objects that are not charged are also said to be _____. They have _____.A. neutral ; no electrons and protonsB. neutrons ; less protons than electronsC. neutral ; equal numbers of protons and electrons

D. natural ; more neutrons than protons and electrons

3. To become charged, objects need to either lose or gain _____.A. protonsB. electronsC. neutrons

4. The nucleus charge is ______ because _____.A. neutral ; it has equal numbers of positive and negative chargesB. neutral ; all charges are outside the nucleusC. positive ; it has positively charged protons and uncharged neutrons *D. negative ; it has more electrons than protons

5. A sodium ion, Na+

has a net charge of +1 because ______.A. it has only one protonB. it has one less electron than protons *C. it has one less proton than electronsD. it gained one more proton from another atom

6. When you rub an inflated balloon with your hair, the balloon ______, your hair_____.

A. becomes negatively charged ; stays neutralB. becomes positively charged ; stays neutralC. becomes positively charged ; becomes negatively chargedD. becomes negatively charged ; becomes positively charged *

7. When two objects repel, then they surely are _____.A. both positively chargedB. both negatively chargedC. both of the same charge


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D. of opposite charges

8. If you rub two objects together, how will you know which one becomespositively charged, and which one becomes negatively charged?A. The rougher object becomes positive, the smoother one becomes

negative.B. The shinier object becomes positive, the duller one becomes negative.C. The rubbed object becomes negative, the other becomes positive.D. Check how the rubbed object interacts with other objects of known

charge.


9. What charges will be acquired by PVC and woolrubbed with each other?

A. PVC: positive; wool: negativeB. PVC: negative; wool: positive *C. both will have positive chargesD. both will have negative charges

The PVC will gain electrons from the wool.

10. Which rubbing material will create the most charge on a glass rod?

A. furB. human hairC. silk *D. wool

NEXT

leatherglass


rubberstyrofoam

polyvinylchloride(PVC)

Increasingtendencyto gainelectrons


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Lesson 2

Interactions between charged bodies

In this lesson, you shall:

Describe and predict how charged and uncharged bodies interact witheach other.

Discuss the different charging processes: conduction, induction andpolarization.

EXPLORE:Are you ready to learn more about charges and how they interact? Lets explore!In the previous lesson, you learned how a body becomes charged. In this lesson

we focus on the following question: How do c harged bod ies interact wi th eachother?

2.1 Web-page reading: Attraction and repulsionYou saw in the first lesson how different combinations of charged bodies eitherattract or repel each other. Read the following page to review some ideas, andto ready you for further for this new lesson.http://www.gcsescience.com/pse3-electrostatic-charge-attraction-repulsion.htm

How about neutral objects? How come they also get attracted to charged

bodies? Write down your initial explanation as to why neutral bodies behave assuch.

Then go on to read this page:http://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htm

Lets do a comprehension check on what you just read. Click on the T if thestatement is TRUE. Click F if the statement is FALSE.

1. Bringing a charged body near a neutral body will cause it to become

charged.

2. Bringing a positively charged body close to a neutral body will causeelectrons to rush to the side near the positively charged body.

3. Bringing a negatively charged body close to a neutral body will causeprotons to rush to the side near the positively charged body.

T F

T F

T F
http://www.gcsescience.com/pse3-electrostatic-charge-attraction-repulsion.htmhttp://www.gcsescience.com/pse3-electrostatic-charge-attraction-repulsion.htmhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.gcsescience.com/pse3-electrostatic-charge-attraction-repulsion.htm


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Lets now find out in the next part what the answers to these questions are.

2.2 Charging balloons. Interactive simulation exploration.

Recall what you did in the previous lesson with balloons. You saw how therubbed balloon interacted with another balloon, your hair, bits of paper, and withthe wall. However, we cannot really see the movement of charges into or out ofthe balloon.

Open this interactive simulation:

http://phet.colorado.edu/en/simulation/balloons (You may have to install a Java program for the simulation to play.)

As you explore the animation, keep in mind these questions:

a. What charge occurs in the balloon after it is rubbed on the sweater?b. What net charge does the sweater therefore acquires?c. What transfers between bodies to cause these bodies to become

charged?d. What happens between objects with unlike charges?e. What happens between objects with like charges?f. Explain why the charged balloon sticks to the wall. Was the wall

charged?

Again, note down answers in your notebook or note-file.

End o f EXPLORE:

At the start of this lesson, you reviewed the basic interactions between chargedobjects. You then learned how neutral objects can get attracted to chargedobjects, even as they stay neutral. The redistribution of electrons in the neutralbody allows it to be attracted by (or to attract) charged bodies.

Go back to the three TRUE-or-FALSE questions in Activity 2.1 and see if you arenow convinced of the correct answers.

In the next activities, you will see and use simple devices that can detect thepresence of charges.

NEXT
http://phet.colorado.edu/en/simulation/balloonshttp://phet.colorado.edu/en/simulation/balloonshttp://phet.colorado.edu/en/simulation/balloons


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FIRM UP:

Your goal in this section is to learn and understand these key concepts:

An electroscope is a device used in detecting the presence or absence ofcharge.

Objects can be charged by conduction or induction.

Keep in mind these questions as you do the next activities:

What happens when a charged body is brought near a neutral body?

Besides rubbing, through what other ways can bodies be charged?

2.3 An electroscope

Read the following webpage:http://www.gcsescience.com/pse4-electrostatic-gold-leaf-electroscope.htm

Then watch this video:http://www.youtube.com/watch?v=2PmWlPjV6n0&feature=fvwrel

Check your comprehension through the following questions:

1. The electroscope is a device used to ______.A. see chargesB. detect charges in bodies *C. measure the amount of charges in bodiesD. count the number of electrons going in or out of bodies

2. Identify the parts of the electroscope. Click and drag the names to the rightboxes.

Cap or knob

Leaf

Insulation

Conducting stem
http://www.gcsescience.com/pse4-electrostatic-gold-leaf-electroscope.htmhttp://www.gcsescience.com/pse4-electrostatic-gold-leaf-electroscope.htmhttp://www.youtube.com/watch?v=2PmWlPjV6n0&feature=fvwrelhttp://www.youtube.com/watch?v=2PmWlPjV6n0&feature=fvwrelhttp://www.youtube.com/watch?v=2PmWlPjV6n0&feature=fvwrelhttp://www.gcsescience.com/pse4-electrostatic-gold-leaf-electroscope.htm


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Alternate item, if above item cannot be programmed:

2. Which of the following items can be used as the stem for the electroscope?A. a plastic spoonB. a popsicle stickC. a metal paperclip with its plastic coating intactD. a metal paperclip with its plastic coating at its ends removed

3. The foil leaf repels when ______ is placed near its knob or cap.A. a persons handB. a positively charged bodyC. a negatively charged body is placed near

D. a charged body, either negative or positive *

4. If a negatively charged body is brought near the knob or cap, the leavesbecome _____ and they _____.

A. positively charged ; attractB. negatively charged ; attractC. positively charged ; repelD. negatively charged ; repel *

5. If a positively charged body is brought near the knob or cap, _____. Thismakes the leaves _____.

A. electrons go up from the leaves to the knob; negatively chargedB. electrons go down from the knob to the leaves; negatively chargedC. electrons go up from the leaves to the knob; positively charged *D. electrons go down from the knob to the leaves; positively charged

2.4 Hands-on: Make your own electroscope

After having watched how an electroscope can be made, try doing it yourself!

Heres another good video on how to make an electroscope. Pay attention tosome details that will help make sure your electroscope will work. Click on thelink to watch the video found athttp://www.youtube.com/watch?v=jBF-144bV18&feature=related

Case or cover
http://www.youtube.com/watch?v=jBF-144bV18&feature=relatedhttp://www.youtube.com/watch?v=jBF-144bV18&feature=relatedhttp://www.youtube.com/watch?v=jBF-144bV18&feature=relatedhttp://www.youtube.com/watch?v=jBF-144bV18&feature=relatedhttp://www.youtube.com/watch?v=jBF-144bV18&feature=relatedhttp://www.youtube.com/watch?v=jBF-144bV18&feature=related


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Then when vinylis brought away,the leaves repel.

6) Glass (positivelycharged) is

brought near, andthe leaves repelfurther.

At the 4:21 mark, the narrator says, A similar sequence of events happens if youcharge it using a positively charged object instead, and then touch it with myfinger again.

Try doing these steps with your own electroscope. Then fill up the table below,

this time with a positively charged body being used to charge the electroscope.

Process description Diagram Explanation Charge ofthe leaves

(at the end ofprocess)

1) Positively chargedobject is broughtnear to the knoband the leavesrepel.

2) Positively chargedobject is broughtaway and theleaves fall backdown.

3) Positively chargedobject is broughtnear again, and

then fingertouches the knobwhile the chargedobject is still heldnear.

4) Positively chargedobject is thenmoved away and


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the leaves repel.

5) Positively chargedobject is brought

near, but this timethe leaves close.Then when objectis brought away,the leaves repel.

6) Negativelycharged object isbrought near, andthe leaves repelfurther.

Was it easy to provide a different set of explanations to the apparently very identicalobservations? What did you notice about your explanations?

Keep in mind that only electrons can be moved within and between bodies to cause

bodies to become charged. Recall the three True-orFalse questions at the start ofEXPLORE (Activity 2.1) Compare your initial answers with the results of this activity.

2.7 Webpage readings: Charging processes

Open and read the following websites. Keep in mind the following questions as

you read:

How could neutral objects be attracted by charged objects?

What kinds of objects can be used in charging by conduction?

What kinds of objects can be used in charging by induction?

Whats the difference between charging by conduction and by induction?

What is polarization? How does it happen?

How is grounding involved in these charging processes?

In this web page, youll see how neutral objects get attracted to charged objects.

http://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htm

In the following web pages, youll see how neutral objects can be chargedthrough two different processes: conduction and induction.

http://www.studyphysics.ca/30/charging.pdfhttp://www.physicsclassroom.com/class/estatics/U8L2b.cfm http://www.physicsclassroom.com/class/estatics/U8L2c.cfm
http://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.studyphysics.ca/30/charging.pdfhttp://www.studyphysics.ca/30/charging.pdfhttp://www.physicsclassroom.com/class/estatics/U8L2b.cfmhttp://www.physicsclassroom.com/class/estatics/U8L2b.cfmhttp://www.physicsclassroom.com/class/estatics/U8L2c.cfmhttp://www.physicsclassroom.com/class/estatics/U8L2c.cfmhttp://www.physicsclassroom.com/class/estatics/U8L2c.cfmhttp://www.physicsclassroom.com/class/estatics/U8L2b.cfmhttp://www.studyphysics.ca/30/charging.pdfhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htm


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Re-read the web pages, this time with a pen in hand you write down on yournotebook answers to the questions above.

2.8 Hands-on: Charging by induction and conduction

Using your home-made electroscope and other materials described in thereadings, demonstrate charging by conduction and induction.

Have as your audience your siblings, parents, or neighbors. Having them askquestions that you gladly answer will enhance your understanding and masteryof the lesson.

End of FIRM UP:

In this section, you have further explored charges using a simple device, theelectroscope. You have also investigated and discussed conduction andinduction, two ways through which objects can become charged. You alsoencountered grounding, and how it is used as a step in charging or dischargingbodies.

So now, explain in your own words how neutral objects can be attracted tocharged bodies. Please also explain how bodies can become charged throughconduction and induction? Finally, explain what kinds of bodies can be chargedthrough conduction and / or induction.

If you have difficulty explaining, go back to the readings and Web pages in thissection!

Now that you know the important ideas about this topic, lets go deeper bymoving on to the next section.

NEXT

DEEPEN:Your goal in this section is to take a closer look at some aspects of the topic.Here you will complete two worksheets that will check on your understanding ofthe charging processes. You will then read Web pages that further elaboratehow even neutral objects participate in electrical interactions simply because theyare polarized.


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2.9 Worksheets: Charging processes

Using your home-made electroscope and other materials described in thereadings, demonstrate charging by conduction and induction. Then open theweb page below and answer the worksheet.

http://dev.physicslab.org/Document.aspx?doctype=5&filename=Compilations_CPworkbook_ElectrostaticsConductionInduction.xml

See the notes and questions that further clarify the differences between conductors andinsulators, and how each of these kinds of materials can be charged. You may re-openthe websites in the previous activity to help you answer the questions in this worksheet.

Worksheet: 3-ele-01_charging_by_induction.doc

CHARGING BY INDUCTION

You can charge objects by a process called induction. You dont needto actually touch the object with some other already charged materialbut just bring it in close proximity. The force then acts from a distance

and induces the charge.

The two spheres are made out of metal because metals have manyfree electrons that can easily move and are good conductors of

electricity. We also need to use a non-conducting strip of material thatwe can charge by friction.

1. Before the experiment is begun, will the metal spheres and the

strip be charged or uncharged? This is now tested with thecoulombmeter. What does it tell you about the charge of bothspheres?

2. What material is being used for friction charging?
http://dev.physicslab.org/Document.aspx?doctype=5&filename=Compilations_CPworkbook_ElectrostaticsConductionInduction.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Compilations_CPworkbook_ElectrostaticsConductionInduction.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Compilations_CPworkbook_ElectrostaticsConductionInduction.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Compilations_CPworkbook_ElectrostaticsConductionInduction.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Compilations_CPworkbook_ElectrostaticsConductionInduction.xml


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3. What kind of charge will be on the strip after it has been rubbed

with the duster?

Now the strip is charged by rubbing it vigorously with a duster.Follow the sequence of events in the demonstration as shown belowand mark on the diagrams what happens to the charge as the

experiment progresses. At first the metal spheres are touching butthe charged strip is well away from them.

I. Uncharged metal spheres, where are the positive and negative

charges?

A B


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II. The charged strip is brought near to but not touching one of the

metal spheres A.

III. Keeping the charged strip near to sphere A, separate the metal

spheres.

IV. Remove the charged strip.

V. Checking the charge on metal spheres A & B.

Charge on A / nC

Charge on B / nC

a. What kind of charge has moved? .

b. Where did the charge move?fromto.

A B

BA

A B


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c. What would you expect to happen if A and B are made to touch

again?

2.10 Webpage reading: Polarized objects and molecules

Review the webpage below:http://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htm

The word polarized is not mentioned in the page. However, see that the neutralobject has its charges not evenly distributed. This body is polarized by thecharged body brought near it. Some electrons are repelled down to its bottompart, leaving the upper part positively charged. The whole body is still electricallyneutral. This body is polarized, as it has positively charged and negativelycharged sides or ends.

Read the page below. Explore the page, and see for yourself why water is soessential and called the universal solvent. Click on the following site:http://www.edinformatics.com/interactive_molecules/water.htm

Note that dissolving things is also dependent on the electrical properties ofmolecules!

End o f DEEPEN:

In this section, you strengthened your understanding of the different chargingprocesses. You then read about how even neutral bodies participate in electricalinteractions.

What new realizations do you have about the topic? What new connections haveyou made for yourself?

Now that you have a deeper understanding of the topic, you are ready to do thetasks in the next section.

NEXT
http://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htmhttp://www.edinformatics.com/interactive_molecules/water.htmhttp://www.edinformatics.com/interactive_molecules/water.htmhttp://www.edinformatics.com/interactive_molecules/water.htmhttp://www.gcsescience.com/pse5-electrostatic-charge-neutral-attract.htm


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TRANSFER:Your goal in this section is apply your learning to real life situations. You will begiven a practical task which will demonstrate your understanding.

2.11 Jumping and floating beads video analysis

Watch this video:http://www.youtube.com/watch?v=7LxyA-7KIoo

With what you have been learning so far about charging processes, provide anexplanation as to why the beads jump, hover and float, as if by magic.

Compare notes with other on-line learners. How are your explanations similar totheirs? How is your explanation different? Give some feedback to the otherlearners, and see how you can convince them to your explanation. On the otherhand, it may be that it is you wholl need to be convinced to their explanation!

2.12 Lab Activity: Flying tissue bits

Perform the following procedures that approximate the effects you saw in thevideo.

Cut or tear some small bits and strips of tissue paper. Let these bits of tissue lie on thetabletop. Get a bond-paper sized plastic sheet (what we use for covering books andnotebooks) and rub it with cloth or tissue paper. Hold it horizontally a few centimetersabove the tissue bits. Observe closely.

Again, as with the beads in the video, compose an explanation for yourobservations.

End o f TRANSFER:

In this section, your task was to create another demonstration on electrostaticcharging and to provide deeper explanations as to how these effects happen interms of the unseen charges within these objects.

How did you find the performance task? How did this task help you furtherunderstand the science of charges and the interactions between charged andeven neutral bodies? Write down your reflections on your notebook or on a

journal file in your computer.

You have completed this lesson. Before you go to the next lesson, you have toanswer the following post-assessment. If you pass this test, you may move on tothe next lesson. If you do not pass this test, you may go back and review thelesson and take this test again.

NEXT
http://www.youtube.com/watch?v=7LxyA-7KIoohttp://www.youtube.com/watch?v=7LxyA-7KIoohttp://www.youtube.com/watch?v=7LxyA-7KIoohttp://www.youtube.com/watch?v=7LxyA-7KIoo


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2.13 Lesson 2 Quiz

1. When a positively charged body is brought near a neutral body, the neutralbodys near side becomes _____, while the far side becomes _____.

A. negative ; positive *B. positive ; negativeC. positive ; also positiveD. negative ; also negative

2. When a negatively charged body is placed near an electroscopes knob,electrons _____, and the leaves become _____.

A. move upward to the knob ; positively chargedB. move upward to the knob ; negatively chargedC. move downward to the leaves ; positively chargedD. move downward to the leaves ; negatively charged *

3. Metals are typically charged by _____, because they have _____.A. induction ; lots of excess electronsB. rubbing ; a strong capacity to gain electronsC. grounding ; a strong tendency to release electrons to the groundD. conduction ; free electrons that can move from one body to another *

4. When charged non-metallic objects are used to charge another body, whathappens is _____ because _____.

A. conduction ; the bodies are touching each otherB. induction ; the bodies are not really touching each otherC. induction ; non-metals cannot pass electrons between themD. conduction ; non-metals can also pass electrons between them

5. Touching the electroscope knob while a positively charged body is near it willcause electrons to go _____, and the leaves become _____.

A. into the knob from the finger ; positively chargedB. into the knob from the finger ; negatively charged *C. out of the knob and into the finger ; positively chargedD. out of the knob and into the finger ; negatively charged

6. Touching the electroscope knob while a negatively charged body is near it willcause electrons to go _____, and the leaves become _____.

A. into the knob from the finger ; positively chargedB. into the knob from the finger ; negatively chargedC. out of the knob and into the finger ; positively charged *D. out of the knob and into the finger ; negatively charged


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7. A positively charged sphere W is brought near two neutral metal spheres Xand Y that are touching each other. Sphere Y was then brought away to theright, removed from its contact with sphere X while sphere W is still nearsphere X.

What will be the charges of spheres X and Y?

A. X becomes negatively charged ; Y stays neutralB. X becomes positively charged ; Y stays neutralC. X becomes positively charged ; Y becomes negatively chargedD. X becomes negatively charged ; Y becomes positively charged *

8. A negatively charged sphere W is brought near two neutral metal spheres Xand Y that are touching each other. Sphere Y was then brought away to theright, removed from its contact with sphere X while sphere W is still nearsphere X.

What will be the charges of spheres X and Y?

A. X becomes negatively charged ; Y stays neutralB. X becomes positively charged ; Y stays neutralC. X becomes positively charged ; Y becomes negatively charged *D. X becomes negatively charged ; Y becomes positively charged

+

+++

W YX

+

+++

W YX

? ?

-

---

W YX

-

---

W YX

? ?


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Lesson 3Safety with Charges

In this lesson, you will do the following: Investigate how grounding is implemented in appliances.

Discuss how lightning rods keep us safe during storms.

Keep in mind the following questions as you move on:

How do the charging processes happen in some appliances at home?

What does it mean that some appliances need to be grounded?

How does grounding work to keep us safe?

How does a lightning rod protect us from harm?

EXPLORE:

Lets continue with Lesson 3 of this module! In the previous lesson, you learnedhow charged bodies interact with each other. In this lesson, we will focus on thefollowing questions: What does it mean that some appliances need to begrounded? How does a lightning rod protect us from harm?

3.1 Webpage reading: LightningOpen and read this webpage on electrostatic shock, an introduction to lightning:http://www.gcsescience.com/pse6-electrostatic-charge-shock-spark-danger.htm

Now go on to read more about lightning:

http://environment.nationalgeographic.com/environment/natural-disasters/lightning-profile/

What new learning did you get from the readings? What are still unclear?

Write notes on your notebook or note-files, both key insights and questions thatyou have in your head. Go back to these notes as you move on to the nextactivities.

3.2 Interactive animation on lightningGo to this site where youll see simulations of the effects of lightning:

http://environment.nationalgeographic.com/environment/natural-disasters/lightning-interactive/

From the experience with the interactive animation, think through the followingquestions:

How can we be safe in our homes during thunderstorms?

How can we be safe outdoors during thunderstorms?

Will you be safer inside your car or under a tree? Explain.
http://www.gcsescience.com/pse6-electrostatic-charge-shock-spark-danger.htmhttp://www.gcsescience.com/pse6-electrostatic-charge-shock-spark-danger.htmhttp://environment.nationalgeographic.com/environment/natural-disasters/lightning-profile/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-profile/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-profile/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-interactive/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-interactive/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-interactive/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-interactive/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-interactive/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-profile/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-profile/http://www.gcsescience.com/pse6-electrostatic-charge-shock-spark-danger.htm


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How are lightning formed in the clouds?

You learned in the previous lessons that only electrons get to movearound and between bodies. Is there anything in the animations thatseem to contradict this idea? How can this be corrected or improved?

End o f EXPLORE:

At the start of this lesson, you explored about electric surges and lightning. Younow may have new ideas or insights about lightning and safety with electricity.You may also have more questions in your head now after the Webpagereadings and the interactive simulation.

In the next activities, you will read more about staying safe from lightning.

NEXT

FIRM UP:

Your goal in this section is to learn and understand these key concepts:

Lightning rods are devices that keep people safe inside structures that arevulnerable to lightning strikes.

Lightning rods need to be connected to the ground, so that charges will beconducted to the ground, sparing the structure and the people inside fromdamage.

3.3 Readings on Safety with Lightning

Read the following web-pages. As you read, you may need to review your notesfrom the previous lessons or activities to understand some parts.

In this web page, you will read tips on how to be safe during thunderstorms.

http://environment.nationalgeographic.com/environment/natural-disasters/lightning-safety-tips/

Learn more about lightning in this web page:

http://www.lightning.org/faq?tid=86

This web page has information on how houses are kept safe by properly installedlightning rods:

http://www.ehow.com/how-does_4588127_lightning-rod-protect-house.html
http://environment.nationalgeographic.com/environment/natural-disasters/lightning-safety-tips/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-safety-tips/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-safety-tips/http://www.lightning.org/faq?tid=86http://www.lightning.org/faq?tid=86http://www.ehow.com/how-does_4588127_lightning-rod-protect-house.htmlhttp://www.ehow.com/how-does_4588127_lightning-rod-protect-house.htmlhttp://www.ehow.com/how-does_4588127_lightning-rod-protect-house.htmlhttp://www.lightning.org/faq?tid=86http://environment.nationalgeographic.com/environment/natural-disasters/lightning-safety-tips/http://environment.nationalgeographic.com/environment/natural-disasters/lightning-safety-tips/


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Check your comprehension of the readings by assessing the following actionsduring a thunderstorm. Click on the S button if the action is SAFE. Click the Ubutton if it is UNSAFE.

1. Stay indoors during thunderstorms.

2. Take shelter under the tallest tree you can find.

3. Crouch low on the ground.

4. Continue watching television in your house.

5. Stay inside your car when caught outside.

6. Lightning rods need to be properly grounded.

7. One lightning rod is enough to protect a big subdivision.

How sure are you with your answers?Do you have them know-how on safety with lightning?

Lets find out the answers to these questions by going to the next part.

1. SAFE. If a thunderstorm starts and you are indoors, stay indoors. Wait it outbefore going out to your next destination.

2. UNSAFE. The tallest tree will be most likely hit by lightning. And if you areunder it when it gets hit, charges may also zap to you sideways from thetrunk.

3. SAFE. Crouching low on the ground will lessen the risk of getting hit bylightning. Do this only of course if no shelter is within a short run from whereyou are.

4. UNSAFE. Continuing to use the television during a thunderstorm increasesthe risk of lightning hitting your house.

5. SAFE. In case your car gets hit by lightning, electricity will be conductedquickly into the ground. Of course, close your windows and dont be touchingyour cars metal body, or else youll be unsafe.

6. SAFE. An ungrounded lightning rod is useless. It may even be increasing therisk of damaging the house, as it will cause the discharge to flow through thehouse.

7. UNSAFE. Even for a big house, more than one lightning rod is needed. Whatmore for a big subdivision.

S U

S U

S U

S U

S U

S U

S U


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End of FIRM-UP:

In this part of the lesson, you learned about how lightning is created, and how wecan be safe from lightning. If you did not do well in the comprehension checkabove, then you may not be very safe when the next thunderstorm happens!

Go back and review the readings and the interactive website. You may trylooking at other related websites to help further clarify your unserstanding.

If you did well (perfect or just 1 mistake), then move on to the next part.

NEXT

DEEPEN:Your goal in this section is to take a closer at another safety mechanism, this

time inside your own homes: grounding of some appliances.

Here you will read about appliances and their plugs and the outlets where youplug them in. You will also examine your own appliances plugs and outlets.

3.4 Webpage readings: Ground wires, 3-prong plugs and 3-hole outletsOpen the following web-pages and read on ground wires and 3-prong plugs and3-prong outlets. As you read, think of the following questions:

Why do some appliances have 3-prong plugs?

Why are some outlets with 3 holes? Whats the difference with 2-prong plugs and 2-hole outlets?

What is grounding? What is a ground wire for?

How do these things help keep us safe?

The web page below discusses the differences between 2-pronged and 3-pronged plugs in appliances, and what the 3rd prong is for.

http://electronics.howstuffworks.com/everyday-tech/question110.htm

The web page below discusses how the 3-hole outlet should have the groundingconnection.http://hyperphysics.phy-astr.gsu.edu/hbase/electric/bregnd.html

Take down notes and answers to the questions in your notebook.
http://electronics.howstuffworks.com/everyday-tech/question110.htmhttp://electronics.howstuffworks.com/everyday-tech/question110.htmhttp://hyperphysics.phy-astr.gsu.edu/hbase/electric/bregnd.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/electric/bregnd.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/electric/bregnd.htmlhttp://electronics.howstuffworks.com/everyday-tech/question110.htm


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3.5 Home-based explo: What appliances have ground wires and 3-prongplugs?

Now that you have read about ground wires and 3-prong plugs and 3-hole

outlets, it is time for you to actually look around your house to see these thingsfor yourself. Do the following:

1. List down appliances that have 2-prong plugs and those that have 3-prongplugs. Look also for appliances that have 2-prong plugs but have groundwires sticking out from it.

Appliances with 2-prongplugs

Appliances with 2 prongs,but with a ground wiresticking out from it

Appliances with 3-prongplugs

Why do you think these appliances in the right column need to have 3 prongs intheir plugs?

2. Ask your parents or elder siblings the following:

Do we have appliances that originally have 3 prongs, but we now use in 2-hole outlets? (either by using an adapter or by having the 3

rdprong taken

out)

Why do some appliances have ground wires? Where do we connectthese ground wires?

End o f DEEPEN:

In this part of the lesson, you learned how to be safe from lighning, and fromelectric shock while using your electrical appliances.

In the next part, youll do something that will bring you into a usefulunderstanding of what youve been learning so far.

NEXT


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TRANSFER:Your goal in this section is apply your learning to real life situations. You willinterview some people who actually work with these safety devices withelectricity.

3.6 Interviews: electrician or an electrical safety inspector / engineer

1. Go to a hardware store. Ask someone there about the differences betweenthe 2-prong plugs and 3-prong plugs, and 2-hole and 3-hole outlets.

2. Go to the city or municipal safety engineers office. Interview an electricalsafety inspector / engineer about grounding installations at residential houses.

Ask about how home builders are complying with this safety requirement.

3. If you have an electrician in your neighborhood, ask him/her to show you theground wiring in your houses 3-hole outlets for some of your appliances.Inquire further on how these things keep you safe from electric shocks.

Submit a one-page double-spaced report about the results of your interview.

End o f TRANSFER:

In this section, your task was to really see the safety features of ground wiresand the specialized plugs and outlets for some appliances. Through interviews,you should have also obtained first-hand information about these safetymechanisms.

Can you already confidently answer the following questions?

What does it mean that some appliances need to be grounded?

How does a lightning rod protect us from harm?

If not yet, then you may have to go back to the readings or interview anotherelectrical safety engineer or electrician.

Review your answers to the Safe-or-Unsafe questions in Activity 3.3. Review aswell the correct answers. If you are still not convinced of the correct answers,and therefore you are cognitively-at-risk of electrical accidents, discuss this as

well with an electrician or an electrical safety engineer.

You have completed this lesson. Before you go to the next lesson, you have toanswer the following post-assessment. If you pass this test, you may move on tothe next lesson. If you do not pass this test, you may go back and review thelesson and take this test again.

NEXT


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1. Lightning rods need to be grounded _____.A. always *B. only during the rainy seasonsC. only if there are people inside the buildingD. only if the houses outlets are not grounded

2. One lightning rod is enough to protect _____.A. one villageB. one family inside a buildingC. one small structure or building *D. many buildings within a kilometer radius

3. A lightning rod is placed on the highest point in a building so that _____.A. it can gather as much charge as possible from the cloudsB. it will be far away from anyones reach, keeping everyone safeC. lightning will most likely hit it instead of other parts of the structure *

D. lightning will more likely hit other lower buildings without lightning rods

4. Which of the following is the BEST thing to do when you are outdoors andsuddenly a thunderstorm occurs?

A. Open your umbrella. It will repel lightning.B. Run for the nearest shed, shelter or building. *C. Take shelter under the nearest tree and stay close to its trunk.D. Walk slowly and carefully. Theres no sense trying to outrun lightning.

5. Will an appliance with 3-prongs in its plug, still function if it is plugged into a 2-hole outlet? (either the 3

rdprong is removed or an adapter with 2 prongs is

used)A. Yes, but it poses hazards of electric shock to its users.B. Yes. It is common practice to remove the 3

rdprong or use an adapter.

C. No. The third prong is essential, and the appliance will not work at all.D. No. The appliance may still work for a while, but it will stop working

after some time.

6. Which of the following sets of appliances either has a ground wire or a three-pronged plug?

A. cellphone charger, electric fan, and TVB. desktop computer, DVD player, and oven toasterC. washing machine, most laptops, and electric fansD. washing machine, electric stove, and shower heater *

7. Where should ground wires (of appliances that have them) be connected?A. to the TV antennaB. to the screw that holds the wall outlets coverC. to the metal water pipes that go into the ground *D. to the concrete wall of the house, through an iron nail

NEXT


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Lesson 4Applications of charges and charging processes

In this lesson, you will:

Discuss practical and technology applications of the charging process and

the interactions between charged bodies. Investigate and report on how concepts on charges are applied in

industries and in cleaning up the air.

Keep in mind this question as you start this lesson and perform the nextactivities:

How are these concepts on charges applied in industries and in cleaningup the air?

EXPLORE:

Congratulations! You are now in Lesson 4 of this module on Electricity. In theprevious section you looked at real world applications to protect you from electriccharges. In this lesson, we focus on the following question: How are theseconcepts on charges applied in industries and in cleaning up the air?

4.1 Webpage reading: industrial application of electrostatic charging

Start this lesson by reading these web-pages. See how electrostatic chargingand the interactions between charged objects are used in a variety of

applications.

This web page discusses how spray-painting uses electrostatic interactions givesurfaces a smooth coat of paint:http://www.gcsescience.com/pse8-electrostatic-charge-paint-spray.htm

Quite similar to the previous page, this web page discusses how electrostaticrepulsion is applied in insecticide sprays:http://www.gcsescience.com/pse12-electrostatic-insecticide-spray.htm

This web page discusses how an inkjet printer applies electrostatic interactions: http://www.gcsescience.com/pse9-electrostatic-charge-inkjet-printer-nozzle.htm

Even photocopiers apply electrostatic charging and interactions! Read this pageto see how:http://www.gcsescience.com/pse10-electrostatic-photocopier.htm
http://www.gcsescience.com/pse8-electrostatic-charge-paint-spray.htmhttp://www.gcsescience.com/pse8-electrostatic-charge-paint-spray.htmhttp://www.gcsescience.com/pse12-electrostatic-insecticide-spray.htmhttp://www.gcsescience.com/pse12-electrostatic-insecticide-spray.htmhttp://www.gcsescience.com/pse9-electrostatic-charge-inkjet-printer-nozzle.htmhttp://www.gcsescience.com/pse9-electrostatic-charge-inkjet-printer-nozzle.htmhttp://www.gcsescience.com/pse10-electrostatic-photocopier.htmhttp://www.gcsescience.com/pse10-electrostatic-photocopier.htmhttp://www.gcsescience.com/pse10-electrostatic-photocopier.htmhttp://www.gcsescience.com/pse9-electrostatic-charge-inkjet-printer-nozzle.htmhttp://www.gcsescience.com/pse12-electrostatic-insecticide-spray.htmhttp://www.gcsescience.com/pse8-electrostatic-charge-paint-spray.htm


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This page discusses a very relevant application of electrostatic charging andinteractions for reducing pollution from chimneys:http://www.gcsescience.com/pse11-electrostatic-chimney-pollution.htmError!

Hyperlink reference not valid.

You can actually just click the right-arrow (next page) button at the bottom.

Which of these applications do you appreciate most? Why?

Have you heard any other applications of electrostatics and charging processesnot mentioned in these pages? Search articles on these applications and sharewhat you get to your network of online learners. Find time to read the pagesshared by other learners to you.

End o f EXPLORE:

In this first part of the last lesson, you read and learned about severalapplications of electrostatic charging and interactions. Its amazing how we mayhave already been using these devices, yet we are not mindful, until now, of thesimple science ideas behind them.

In the next activities, you will simulate and investigate on the least familiar, yetvery relevant and important application of electrostatic charging and interactions:the electrostatic precipitator.

NEXT

FIRM UP:Your goal in this section is to learn and understand this key concept:

Electrostatic charging is useful in cleaning up the air of pollutantsfrom different industrial facilities

Keep this question in mind as you do the next tasks:

How are these concepts on charges applied in industries and in

cleaning up the air?
http://www.gcsescience.com/pse11-electrostatic-chimney-pollution.htmhttp://www.gcsescience.com/pse11-electrostatic-chimney-pollution.htmhttp://www.gcsescience.com/pse11-electrostatic-chimney-pollution.htmhttp://www.gcsescience.com/pse11-electrostatic-chimney-pollution.htm


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4.2 Hands-on: Cleaning up the air using balloons

How is electrostatics useful?To better appreciate the applications of electrostatic charging, do this simulationon cleaning the air using charged balloons. Open and study the web page

below:

http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_air/cub_air_lesson10_activity2.xml

Perform the steps to simulate how a charged balloon can attract pollutingparticulates in the air. Again, it will be good if you have family or neighbors asyour audience in this demonstration. Enjoy your show and the question-and-answer portion after your demonstration.

How effective is your balloon air cleaner? Is it 100% efficient? Will it be useful?

Explain.

NEXT

DEEPEN

4.3 Web-page reading: Electrostatic precipitator

To deepen your understanding of this important application of electrostatics, readthe following web pages:

These web pages are nice follow-ups to your previous reading on theelectrostatic precipitator:http://www.explainthatstuff.com/electrostaticsmokeprecipitators.html http://anto-hendarto.blogspot.com/2011/05/electrostatic-precipitator.html

Take down notes, specially details that will help you answer these questions.Draw diagrams that demonstrate your understanding of how electrostaticcharging is applied. .

How does an electrostatic precipitator work?

Why would we need these electric precipitators?

What facilities are installed with these electrostatic precipitators?
http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_air/cub_air_lesson10_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_air/cub_air_lesson10_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_air/cub_air_lesson10_activity2.xmlhttp://www.explainthatstuff.com/electrostaticsmokeprecipitators.htmlhttp://www.explainthatstuff.com/electrostaticsmokeprecipitators.htmlhttp://anto-hendarto.blogspot.com/2011/05/electrostatic-precipitator.htmlhttp://anto-hendarto.blogspot.com/2011/05/electrostatic-precipitator.htmlhttp://anto-hendarto.blogspot.com/2011/05/electrostatic-precipitator.htmlhttp://www.explainthatstuff.com/electrostaticsmokeprecipitators.htmlhttp://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_air/cub_air_lesson10_activity2.xmlhttp://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_air/cub_air_lesson10_activity2.xml


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4.4 Electrostatic precipitator: Make a model

Another way to deepen your understanding is by making another model of thetechnology application that you are studying. Open and study the page below:http://www.woodrow.org/teachers/chemistry/1989/12model-electrostatic.html

If you can, collaborate with other online learners on how to build this model. Thisway you can share with the expenses and the effort in putting the modeltogether. Also, with collaboration, youll have other persons to compare noteswith of your understanding of the lessons so far. You may visit your schoolslaboratory and use their available materials to build the model.

In your notebook, write a brief reflection on your experience of building a workingmodel of the electrostatic precipitator. Do you think this device is worth the effortand the electricity used up for it? Why or why not?

NEXT

TRANSFER

In this modules closing lesson, your final task is to check on a nearby factory orpower plant in your community, and see whether it has electrostatic precipitatorsinstalled in its chimneys. You may collaborate with up to three (3) other onlinelearners. Your output will be a multimedia report of your investigation. Yourreport shall be uploaded for a panel of reviewers to evaluate and score.

Your report shall include the following:

Narration of your preparations for the interviews: inquiries made,appointments set, etc.

Documentation of your investigation: Transcripts and/or recordings ofinterviews, videos or pictures of your visit to the facility.

Feedback to the facility administrators: Commendations if they have beenvery helpful and that they have been using the precipitators properly andeffectively; Suggestions if the operation can still be improved; orcomplaints filed to government authorities if you think the facility is not

using the electrostatic precipitator.

Your report should be comprehensive, and engaging, and demonstrates amethodical approach to addressing the issue.
http://www.woodrow.org/teachers/chemistry/1989/12model-electrostatic.htmlhttp://www.woodrow.org/teachers/chemistry/1989/12model-electrostatic.htmlhttp://www.woodrow.org/teachers/chemistry/1989/12model-electrostatic.html


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Heres a rubric by which your report shall be scored:

Criteria 4 3 2 1Comprehensiveness of thereport

Very comprehensive.Important facts andevidences weregathered. Additionalinformation presentreflects students deepunderstanding.

Comprehensive.Acceptable, butsome things canstill be added.

Some keyinformationare lacking.Not quitecomplete.

Quiteunsubstantial.More workneeds to bedone.

Engaging Very engaging. Thereport is worth sharingto the national newsagencies.

Engaging. Goodmaterial for alocal news item.

Not engaging.A number ofthe audienceis easilydisinterested.

Notengaging.Hardlyanyone wantsto finish thereport.

Methodicallyaddressedthe issue

Very scientific andmethodical.Variables are clearlydefined. Data andarguments aremethodically

presented.Writingstyle is interestingand vivid.

Scientific andmethodical, butthe writing styleand

presentationcan still beimproved.

Shows somelapses orgaps in themethods andanalysis ofthe issue.

Very seriousgaps in themethodsand analysisare presenton theissue.

Before you go on to the post-assessment, go first through a review on theconcepts and ideas learned from the different activities.

Open the link below, and answer the questions there.http://www.gcsescience.com/pse13-electrostatic-charge-questions-answers.htm

If you commit some mistakes, you are advised to return to the Lessons and theWebpage readings to clarify further your missed or incomplete understanding.

Write a 1 to 2-page reflection on your experience in the entire module. You maychoose to answer one, some, or all of these guide questions:

What do you consider your most important learning in this module?

What did you find challenging yet engaging?

What did you find difficult and frustrating?

Besides the investigation on electrostatic precipitators, what otherinvestigations related to electrostatic charges and charging could you workon later?

NEXT
http://www.gcsescience.com/pse13-electrostatic-charge-questions-answers.htmhttp://www.gcsescience.com/pse13-electrostatic-charge-questions-answers.htmhttp://www.gcsescience.com/pse13-electrostatic-charge-questions-answers.htm


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POST-ASSESSMENT:Its now time to evaluate your learning. Click on the letter of the answer that youthink best answers the question. Your score will only appear after you answer allitems. If you do well, you may move on to the next module. If your score is not at

the expected level, you have to go back and take the module again.

1. The nucleus of atoms consists of _____, so its charge is ____.A. neutrons only ; neutralB. electrons and protons ; neutralC. protons and neutrons ; positive *D. neutrons, protons and electrons ; neutral

The nucleus is positive because it has protons in it. The negativelycharged electrons are outside the nucleus.

2. A chlorine ion, Cl- has a net charge of -1 because ______.A. it has only one electronB. it has one less electron than protonsC. it has one more electron than protons *D. it gave away one proton to another atom

A chlorine atom has 17 protons in its nucleus and 17 electrons outside. Iteasily gains one more electron, and so it has one more electron thanprotons, becoming a Cl

-ion.

3. If a neutral metal sphere is placed in contact with a negatively charged metalrod, the sphere will _____.

A. remain neutralB. become positively chargedC. become negatively charged as well *D. fluctuate from being positively charged and negatively charged

Some of the excess electrons in the negatively charged rod will transfer tothe initially neutral sphere. This will make the initially neutral sphere alsoin excess of electrons and therefore positively charged.


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4. In charging by induction, a charged body X is placed near to a neutral body Y.If X is positively charged and Y is connected to the ground, Y will _____.

A. remain neutralB. become negatively charged

C. become positively charged as well *D. fluctuate from being positively charged and negatively charged

Body X will cause electrons in body Y to move to the side near body X.With the grounding, electrons will flow into body Y, making it negativelycharged.

http://www.ahsd.org/science/stroyan/APPhysics/CH15/chargi7.gif


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5. If a negatively charged body is to be connected to the ground, then _____.

A. all its electrons will go to the groundB. its excess electrons will go to the ground *

C. it will take in some protons from the groundD. it will take in some electrons from the ground

Only electrons can be added or removed from bodies. A negativelycharged body has excess electrons. When grounded, these excesselectrons will flow to the ground until the body becomes neutral.

6. Which of the following most needs to be grounded?

A. desktop computerB. electric stove *

C. flat ironD. hair dryer

The metal casing of the electric stove has agood chance of becoming electrically in contact with the live wires. Also,charge can accumulate in it. If this happens, the person using it is at riskof an electric shock. With proper grounding, usually done through the 3rd(round) prong in its plug, this risk is minimized, if not entirely eliminated.


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7. Lightning rods are placed _____ of a building.A. at the baseB. above the windowsC. above the highest point

D. on all the corners of the rooftop

Placing rods above the highest points of a building will ensure that if everlightning strikes, it hits the lightning rod, and not any other part of thebuilding.

8. A lightning rod works by _______.

A. conducting the charge to the ground, through the buildingB. conducting the charge to the ground, bypassing the building *

C. collecting the charge into a storage device, for use later as electricity

The charge from lightning is immediately conducted down into the ground,bypassing the building, keeping the people inside the building unharmed.If the lightning rod is not grounded, then electricity will pass through thebuilding and the people in it will not be safe. The great amount of chargecannot be stored (yet) for later use as electricity.

9. A single electrons charge is 1.6 x 10-19

Coulomb. What will be the chargeof a body if it loses 1 billion of its free electrons?

A. 1 x 109

CoulombB. + 1.6 x 10-9 CoulombC. + 1.6 x 10-10 CoulombD. - 1.6 X 10

-10Coulomb

Q = n qe where Q is the charge developedn is the number of electronsqe is the charge of an electron

Q = n qe = ( 1.6 x 10-19 Coulomb per electon) x (1 x 109 electrons)

= 1.6 x 10-10

Coulomb

However, since the body loses electrons, its charge is positive: + 1.6 x 10-10

Coulomb.


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10. If a glass rod is rubbed with Styrofoam, what willbe the sign of their charges?

A. glass rod: positive; Styrofoam : negative *B. glass rod: negative; Styrofoam: positiveC. both will have positive chargesD. both will have negative charges

The Styrofoam will gain electrons from the glass rod.

11. Which rubbing material will create the most chargeon a rubber stick?

A. fur

B. human hair *C. silkD. wool

The more electrons gained by the rubber stick, the greater the chargecreated in it. From among the choices, human hair is highest in theseries, farthest away from rubber. It has the least tendency to gainelectrons, or conversely, it will most easily give its electrons to the rubberstick.

12. The picture at the right shows a green wire attached to

the motor at the underside of a washing machineswash tub. What is this wire and what is it for?

A. It is the power line. Without it the machine willnot run.

B. It is the line to the buzzer alarm. Without it theuser wont hear an alarm even when it is donewashing.

C. It is the grounding wire. It discharges the motorand the whole machine.

D. It is an anti-theft wire. With it attached to themain circuitry, the washing machine will not be

stolen, as the thief will be electrocuted.

The green wire is a grounding wire. Its other endshould be connected to the water pipe outside themachine. This way, charge is prevented from building up in the washingmachine.

leatherglass


rubberstyrofoam

polyvinylchloride(PVC)

Increasing

tendencyto gainelectrons


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13. What could happen if this wire is not firmly connected at either ends?

A. The motor for the wash tub will run, but that for the spin dryer will not.B. The washing machine will not run.

C. The motor will keep running even as the timer goes down to zero.D. The person using the machine might get an electric shock. *

If the grounding wire is not connected, then the charge that mayaccumulate in the machine may cause an electric shock on the personusing it.

14. Which of the following will be the BEST thing to do when you are in your car,on a long trip on an open plain highway, and a thunderstorm suddenly starts?

A. Get out of your car and take shelter under the nearest tree you can

find.B. Stay in your car and take a stop in the next stable shelter or gasstation. *

C. Stay in your car, but stop at the roadside and wait for the storm to beover.

D. Stay in your car, but turn off the radio and lights, as using theseincreases the risk of lightning hitting your car.

People in open fields (with no trees or houses) are at risk of getting struckby lightning. The other risks above should also be avoided, but the mostfatal of them is the first.

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