© Boardworks Ltd 2003 KS4 Static electricity. © Boardworks Ltd 2003 Charge ParticleCharge Proton...
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Transcript of © Boardworks Ltd 2003 KS4 Static electricity. © Boardworks Ltd 2003 Charge ParticleCharge Proton...
© Boardworks Ltd 2003
KS4 Static electricity
© Boardworks Ltd 2003
Charge
Particle Charge
Proton
Neutron
Electron
+1
none
-1
© Boardworks Ltd 2003
Charge, attraction and repulsion
© Boardworks Ltd 2003
Attraction and repulsion
Positive and positive ________
Negative and negative ________
Positive and negative ________
repel
repel
attract
Like charges repel, unlike charges attract.
© Boardworks Ltd 2003
Charging objects
What do we call the force you get when two materials rub together?
Friction
Let’s say you rub an insulator with a cloth, two things can happen:
A. Electrons move from the cloth to the insulator.
B. Electrons move from the insulator to the cloth.
Let’s look at the two cases in more detail.
© Boardworks Ltd 2003
Electrons move from the insulator to the cloth
Electrons move from the insulator to the cloth.
The cloth becomes negatively charged.
The insulator becomes positively charged.
It is only the electrons that are free to move.
What charge has the cloth?
What charge has the insulator?
+ ++ +
© Boardworks Ltd 2003
© Boardworks Ltd 2003
Electrons move from the cloth to the insulator
Electrons move from the cloth to the insulator.
The cloth becomes positively charged.
The insulator becomes negatively charged.
What charge has the cloth?
What charge has the insulator?
It is only the electrons that are free to move.
© Boardworks Ltd 2003
Identifying an unknown charge
If you have a rod with an unknown charge you can identify the charge using two methods.
If you bring it near a positively charged rod and it is attracted to the rod then the unknown
charge must be ________.
If you bring it near a positively charged rod and it is repelled by the rod then the unknown
charge must be _________.
negative
positive OR
© Boardworks Ltd 2003
Identifying an unknown charge
If the rod is a negative rod then……..
If you bring it near a negatively charged rod and it is attracted to the rod then the unknown
charge must be ________.
If you bring it near a negatively charged rod and it is repelled by the rod then the unknown
charge must be _________.
positive
negative
© Boardworks Ltd 2003
Inducing a temporary charge
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If you bring a negatively charged rod near a piece of paper, why does the paper stick to the rod?
The paper has no charge!
As the rod approaches the paper, the electrons in the paper are repelled away from the rod.
This makes one side of the paper negative and one side positive, a charge has been induced on the paper and the positive side of the paper is attracted to the negative rod.
© Boardworks Ltd 2003
+ - + - + -
+ - + - + -
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If you bring a positively charged rod near a piece of paper, why does the paper stick to the rod?
The paper has no charge!
As the rod approaches the paper, the electrons in the paper are attracted towards the rod.
This makes one side of the paper negative and one side positive, a charge has been induced on the paper and the negative side of the paper is attracted to the positive rod.
Inducing a temporary charge
© Boardworks Ltd 2003
What is the charge on an electron?
A. Positive
B. Negative
C. Neutral
D. Depends upon the atom
© Boardworks Ltd 2003
What force can be used to charge insulators?
A. Gravity
B. Friction
C. Weight
D. Energy