AQA GCSE Physicsharrowsmithtuition.co.uk/topictests/gcse/aqa/4.2.5.pdf · (d) When the potential...

AQA GCSE PhysicsElectricity 4.2.5: Static Electricity & Electric Fields

Name: ________________________

Class: ________________________

Date: ________________________

Time: 60 minutes

Marks:

Comments:

Answers:

60 marks

Q1 to Q4 to be worked through with tutor. Q5 to Q8 to be worked through independently.

http://www.harrowsmithtuition.co.uk/topictests/gcse/aqa/4.2.5.pdf

of 26

A student rubs an acetate rod with a cloth.

Figure 1 shows the charges on the acetate rod and cloth before and after rubbing.

Figure 1

(a) Explain how rubbing an acetate rod with a cloth causes the rod and cloth to becomecharged.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(5)

1

of 26

(b) After charging them, the student moves the acetate rod and the cloth closer together.

Which statement is correct?

Tick one box.

There is no force between the acetate rod and the cloth.

There is a force of attraction between the acetate rod and the cloth.

There is a force of repulsion between the acetate rod and the cloth.

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(2)

of 26

(c) Figure 2 shows a Van de Graaff generator, which is used to generate static electricity.

Figure 2

© Michael Priest

The longer the Van de Graaff generator is switched on, the more charge is stored on themetal dome.

Use an answer from the box to complete the sentence.

decrease increase stay the same

The amount of charge on the metal dome is increased, which causes the potentialdifference between the metal dome and the earthed sphere to

______________ .

(1)

of 26

(d) When the potential difference between the Van de Graaff generator and the earthed sphereis 60 kV, a spark jumps between the metal dome and the earthed sphere.

The spark transfers 0.000025 coulombs of charge to the earthed sphere.

The equation which links charge, energy and potential difference is:

energy transferred = charge × potential difference

Calculate the energy transferred by the spark.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Energy transferred = ______________________ J

(2)

(Total 10 marks)

of 26

(a) The diagram shows a negatively charged plastic rod held near to a thin stream of water.The water is attracted towards the rod.

Which one of the following statements explains what is happening to the charge in thewater?

Tick ( ) one box.

The positive and the negative charges in the water are attractedto the rod.

The positive and the negative charges in the water are repelledby the rod.

The negative charge in the water is repelled by the rod and thepositive charge is attracted to the rod.

The negative charge in the water is attracted to the rod and thepositive charge is repelled by the rod.

(1)

2

of 26

(b) A company that produces bottles of mouthwash found a problem with the automatic fillingsystem.

As the bottles go towards the filler, the bottles move around on the conveyor belt andbecome electrostatically charged. This causes the stream of mouthwash to movesideways, missing the open top of the bottle.

The company came up with an answer to the problem. Before the bottles reach the filler, the bottles pass through a stream of ionised air. The ions in the air neutralise the charge on the bottles.

(i) Explain why the plastic bottles became charged.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(ii) What happens to the structure of an atom to change the atom into an ion?

______________________________________________________________

______________________________________________________________

(1)

of 26

(iii) Earthing the conveyor belt with a conducting wire would not have solved thisproblem.Give a reason why.

______________________________________________________________

______________________________________________________________

(1)

(Total 5 marks)

A pupil did an experiment following the instructions below.

1. Take a polythene rod (AB), hold it at its centre and rub both ends with a cloth.

2. Suspend the rod, without touching the ends, from a stand using a stirrup and nylon thread.

3. Take a perspex rod (CD) and rub it with another cloth.

4. Without touching the ends of the perspex rod bring each end of the perspex rod up to, butwithout touching, each end of the polythene rod.

5. Make notes on what is observed.

3

The diagram below shows how the apparatus is to be set up.

(a) When end C was brought near to end B they attracted each other.

(i) Explain why they attracted each other.

______________________________________________________________

______________________________________________________________

(ii) What would happen if end C were brought near end A?

______________________________________________________________

(3)

of 26

(b) The experiment was repeated with two polythene rods.

(i) Describe what you would expect the pupil to observe as the end of one rod wasbrought near to the end of the other.

______________________________________________________________

______________________________________________________________

(ii) Explain your answer.

______________________________________________________________

______________________________________________________________

(2)

(c) Explain, in terms of electron movement, what happened as the rods were rubbed withthe cloths.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(3)

(Total 8 marks)

of 26

Figure 1 shows a Van de Graaff generator that is used to investigate static electricity.

Before it is switched on, the metal dome has no net charge.

After it is switched on, the metal dome becomes positively charged.

Figure 1

© Michael Priest

(a) Explain how an uncharged object may become positively charged.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(3)

4

of 26

(b) Figure 2 shows a plan view of the positively charged metal dome of a Van de Graaffgenerator.

Draw the electric field pattern around the metal dome when it is isolated from itssurroundings.

Use arrows to show the direction of the electric field.

Figure 2

(2)

of 26

(c) Another positively charged object is placed in the electric field.

Look at Figure 3.

Figure 3

In which position would the object experience the greatest force?

Explain your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Tick one box.

P

Q

R

S

(1)

(2)(Total 6 marks)

of 26

(a) A student rubs a nylon comb on the sleeve of his jumper.

(i) Use words from the box to complete the following sentence.

electrons hand jumper protons

The comb becomes negatively charged because __________________ move

from the student’s ______________________ to the comb.

(2)

5

(ii) What type of charge is left on the jumper?

______________________________________________________________

(1)

(iii) The negatively charged comb is placed close to a charged plastic ruler. The comband the ruler attract each other.

Complete the following sentence by drawing a ring around the correct line in the box.

The ruler is

negatively charged

positively charged

uncharged

(1)

of 26

(b) Electrostatic charge can damage computer chips. People working with computer chips maywear a special bracelet, with a wire joining the bracelet to earth (the earth wire). Anynegative charge on the person will flow through the wire to earth.

(i) Which one of the following materials should the bracelet be made from?

Draw a ring around your answer.

copper plastic rubber


______________________________________________________________

______________________________________________________________

(2)

(ii) Which one of the following words is used to describe the rate of flow of chargethrough a wire?


current resistance voltage

(1)

(Total 7 marks)

of 26

(a) A student takes off his nylon fleece and feels a small electric shock.He realises that this happens because his fleece becomes charged.

Explain why the fleece becomes charged.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(2)

6

(b) Only two of the following statements are correct.

Put a tick ( ) in the boxes next to the two correct statements.

Positively charged objects repel negatively charged objects.

Electrical charges move easily through metals.

Static electricity is safe; it never causes any danger.

An electric current is a flow of electrical charge.

(2)

of 26

(c) The diagram shows a lightning conductor attached to the side of a tall building.

If the building is struck by lightning, charge flows to earth through the lightning conductor.

(i) Which of the materials in the list is used to make the lightning conductor?


copper glass plastic


______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(ii) Complete the sentence by drawing a ring around the correct line in the box.

The resistance of the lightning conductor is

higher than

the same as the resistance of the building.

lower than

(1)

of 26

(iii) It is almost impossible to test different designs of lightning conductor in controlledexperiments during a lightning storm.

Suggest a reason why.

______________________________________________________________

______________________________________________________________

(1)

(Total 8 marks)

(a) The diagram shows a polythene rod being rubbed with a woollen cloth.

The polythene rod becomes negatively charged.

Explain how this happens.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(2)

7

of 26

(b) A student put the charged polythene rod on to a balance. The rod was separated from themetal pan of the balance by a thin block of insulating material.The student then held a second charged polythene rod above, but not touching, the firstrod. The reading on the balance increased.

(i) Explain why the reading on the balance increases.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(ii) The student observed that the nearer the two rods are to each other, the bigger theincrease in the balance reading.

What should the student conclude from this observation?

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(Total 6 marks)

of 26

(a) The diagram shows a student touching the metal dome of a Van de Graaff generator.When the generator is switched on, the metal dome becomes negatively charged.8

Explain why the student’s hair will not stand on end if the polystyrene box is removed.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(2)

(b) When the potential difference between the student and a nearby earthed metal domereached 15 kV, a spark jumped between the student and the earthed dome. The spark transferred a charge of 30 mC. (1 mC = 0.001 C)

Calculate the energy transformed into heat, light and sound by the spark.

___________________________________________________________________

___________________________________________________________________

Energy transformed =_________________________________(3)

(c) What name is given to the energy transferred per unit charge?

___________________________________________________________________

(1)

(Total 6 marks)

of 26

Mark schemes

A detailed and coherent explanation is provided. The student makes logical links betweenclearly identified, relevant points.

Level 1 (1–2 marks):Simple statements are made, but not precisely. The logic is unclear.

0 marks:No relevant content

Indicative content• friction (between cloth and rod) causes• electrons (to) move• from the acetate rod or to the cloth• (net) charge on cloth is now negative• (net) charge on rod is now positive

5

(a) Level 2 (3–5 marks): 1

(b) there is a force of attraction between the acetate rod and the cloth

(reason)1

unlike charges attract

or

negative charges attract positive charges1

(c) increase1

(d) 0.000025 × 60 0001

1.5 (J)1

accept 1.5 (J) with no working shown for 2 marks

[9]

(a) 3rd boxThe negative charge in the water is repelled by the rod and the positive chargeis attracted to the rod.

1

2

(b) (i) friction between bottles and conveyor belt / (plastic) guides

accept bottles rub against conveyor belt / (plastic) guides1

of 26

charge transfers between bottles and conveyor belt / (plastic) guides

accept specific reference eg electrons move onto / off the bottlesreference to positive electrons / protons negates this mark

1

(ii) (the atom) loses or gains one (or more) electrons1

(iii) charge will not (easily) flow off the conveyor belt / bottles

accept the conveyor belt / bottles is an insulator / not a conductoraccept conveyor belt is rubber

1

[5]

(a) (i) Ends have chargeWhich is opposite on each rod

2

(ii) Attracts1

3

(b) (i) Repulsion1

(ii) Ends have same charge1

(c) Electrons move between cloth and rodWhere gather is negativeWhere move from is positive

3

[8]

(a) negatively charged14

electrons are transferred1

from the (neutral) object1

(b) minimum of four lines drawn perpendicular to surface of sphere

judge by eye1

minimum of one arrow shown pointing away from sphere

do not accept any arrow pointing inwards.1

(c) Q

stronger field/field lines closer together therefore stronger force

111

[8]

of 26

(a) (i) electrons1

jumper1

5

(ii) positive

accept protons

accept +1

(iii) positively charged

accept any clear way of indicating the answer1

(b) (i) copper1

it is an (electrical) conductor

only accept if copper is identified

do not accept it conducts heat

accept it conducts heat and electricity

accept copper is the best conductor

accept correct description of conduction1

(ii) current1

[7]

(a) fleece rubs against shirt

it refers to the fleece1

6

orfriction (between fleece and shirt)

(causing) electrons to transfer from one to the other

accept a specific direction of transfer

do not accept charge for electrons

positive electrons negates this mark

movement of protons negates this mark1

(b) Electrical charges move easily through metals.1

An electric current is a flow of electrical charge.1

(c) (i) copper

reason only scores if copper chosen1

of 26

(good electrical) conductor

accept it is a metal

any mention of heat conduction negates this mark1

(ii) lower than1

(iii) accept any sensible suggestion,eg:

• too many variables (to control)

• lightning strikes / storms are random / unpredictable

• do not know which building will be struck

• do not know when a building will be struck

• do not know when lightning will happen

• (very) difficult to create same conditions in a laboratory

• lightning storms are not the same

it is not safe is insufficient

do not accept lightning does not strike the same place twice1

[8]

(a) electrons transfer / removed

do not accept negatively charged atoms for electrons

this only scores if first mark given1

7

to the rod / from the cloth

this does not score if there is reference to any original charge oncloth or rod

‘it’ refers to the rod

accept negative charge transfer to rod / removed from cloth for 1mark

transfer of positive charge / positive electrons scores zero1

(b) (i) rods / charges repel1

creating downward / extra force (on the balance)

accept pushing (bottom) rod downwards

do not accept increasing the weight / mass

charges attracting scores zero1

of 26

(ii) the (repulsion) force increases as the distance between the chargesdecreases

accept there is a negative correlation between (repulsion) force anddistance between chargesor(repulsion) force and distance between charges are inverselyproportional

for both marks

examples of 1 mark answers

force increases as distance decreases

force and distance are inversely proportional

negative correlation between force and distance

repels more as distance decreases

if given in terms of attracting or attraction force this mark does notscore

2

[6]

(a) polystyrene box acts as an insulator

1

8 oris a bad conductor

charge could not build uporall charge would flow to ground if removed

1

(b) 450accept correct substitution and transformation for 1 mark

or4.5 × 10-2

2

(c) potential differencedo not accept volts

1

[5]

of 26

Examiner reports

(a) About half of the students gained this mark.

(b) (i) About half of the students gained one mark for the idea that the bottles rubbedagainst the conveyor belt / guides. Few students went on to link this to the transfer ofcharge.

(ii) About half of the students were able to state what happens to change an atom intoan ion.

(iii) Very few students gained this mark even though a simple answer like ‘the conveyorbelt is rubber’ was sufficient.

2

(a) (i) This was well answered with the majority of candidates choosing the correctresponses.

(ii) About 75 % of candidates correctly said that the remaining charge would be positive.A few candidates gained credit for the answer proton.

(iii) This was question was generally answered correctly.

5

(b) (i) This should have been an easy question and it was for many candidates, but asignificant number did choose plastic or rubber thinking that it was necessary to havean insulator to stop electricity (rarely current or charge) flowing to protect the workerand/or the chip. Most of the candidates correctly choosing copper also gave a correctreason. A few candidates did manage to think or mistakenly write that copper was aninsulator.

(ii) About 75 % of candidates gave the correct answer.

(a) Candidates were generally aware that the two materials rubbed together would createfriction and the build up of static electricity. The award of the second mark was moreproblematical, as although many candidates understood that electrons were involved, theaward of a mark was often negated by responses involving positive electrons orcontradictions in the polarity of the materials after the movement of electrons. A significantnumber of candidates thought that protons were transferred.

(b) Over two thirds of candidates were able to pick the two correct statements, with a furtherthird of candidates being able to pick one correct statement.

(c) (i) The majority of the candidates were aware that copper would be the choice ofmaterial for a lightning conductor because it, being a metal, would conduct electricity.However, some candidates, although receiving one mark for choosing copper, did notreceive credit for their reason for their choice because their responses were in termsof heat conduction.

(ii) Few candidates scored this mark. Most candidates thought that the lightningconductor should have a higher resistance than the building.

(iii) The unpredictability of lightning storms was appreciated by most candidates whogained credit for stating the place, accompanying weather, timing and severity of thelightning strikes rendered a controlled experiment unlikely. The majority of theresponses that did not gain credit were purely in terms of health and safety issues.

6

of 26

(a) This straightforward question again caused students to struggle. The fact that it is electronsthat transfer onto a substance to give it negative charge continues to be beyond manystudents. Often students described protons or positive electrons moving. The other area ofconfusion is that many students thought that the woollen cloth had an initial negativecharge. The gain of negative charge by the rod was from this surplus charge on the wool.

(b) (i) Most students found this application of understanding question too challenging. Themain area of confusion was what a balance actually measures i.e. the downwardforce placed on it. The usual attempt was in terms of transfer of extra charge, in avariety of forms, from the top rod to the bottom. This extra charge was detected bythe balance as an increase in weight or mass. It was rare to see a correct answer.

(ii) Only about a tenth of students scored 1 mark for recognising that as the distancedecreased the force increased. Often this mark was not given because studentssimply repeated, from the stem of the question, that the reading on the balanceincreased instead of stating that there was an increase in force. The essential extrabit of information that it was the charges producing the force was very rarely given.

7

(a) This question was poorly answered with a small majority of the candidates scoring nomarks. In some cases this was due to a lack of knowledge or understanding eg, candidatesrefer to the attraction of the (positive) boy’s body to the negative dome or to the movementof positive charge / protons / positive electrons.In many instances, a lack of precision in the use of English prevented candidates gainingmarks, especially in respect of the second mark point where responses were left at hairsrepelling without further explanation. Some candidates referred to hair standing on end asa result of the person getting a shock and others because the charge was trying to escapefrom the body.

(b) Under a quarter of the candidates scored 2 marks for a correct calculation. A significantnumber of candidates scored 1 mark for answers of either 2 or 0.002 as they had notconverted the kV or mJ correctly, despite the information in the stem.A number of candidates did not seem to have access to a calculator and had donecalculations around the text, sometimes making errors which deprived them of full marks.Of those who did not gain marks, this was evenly spread between those who did nottransform the equation correctly and those who did not transform values properly. At thislevel it is disappointing that over a third of the entry simply multiplied the given numbers;with or without an attempted conversion.

(c) Only half of the candidates gave the correct answer.

8

of 26

AQA GCSE Physicsharrowsmithtuition.co.uk/topictests/gcse/aqa/4.2.5.pdf · (d) When the potential...

Documents

Transcript of AQA GCSE Physicsharrowsmithtuition.co.uk/topictests/gcse/aqa/4.2.5.pdf · (d) When the potential...