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physics Physics For High Schools (KS4)
 
Solved problems for the chapter:
 

Electric Charge

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Electric Charge
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Detailed solution steps are available at:
 
https://en.openprof.com/wb/chapter:electric_charge/3630/


Example 1.

A plastic rod is rubbed with a dry woollen cloth. The rod becomes positively charged. Which statement is correct?


  • Electrons move from the cloth to the rod.

  • Electrons move from the rod to the cloth.

  • Protons move from the cloth to the rod.

  • Protons move from the rod to the cloth

    
Example 2.

A student holds a rod in his hand.




He rubs the rod with a cloth. The rod gains a positive charge. Of which material could the rod be made, and which transfer of charge has happened?


 
material of rod
transfer of charge
 
A
metal
negative charge from rod to cloth
 
B
metal
positive charge from cloth to rod
 
C
plastic
negative charge from rod to cloth
 
D
plastic
positive charge from cloth to rod
 
    
3.

A student rubs a plastic rod with a cloth. The rod becomes positively charged. What has happened to the rod?


  • It has gained electrons.

  • It has gained protons.

  • It has lost electrons.

  • It has lost protons.

    
4.

A plastic rod and a dry cloth are uncharged. The rod is now rubbed with the cloth and they both become charged. The rod becomes negatively charged because some charged particles move from the cloth to the rod. What is the charge on the cloth and which particles moved in the charging process?


 
charge on cloth
particles that moved
 
A
negative
electrons
 
B
negative
neutrons
 
C
positive
electrons
 
D
positive
neutrons
 
    
5.

A plastic rod is rubbed with a dry cloth. The rod becomes positively charged. Why has the rod become positively charged?


  • It has gained neutrons.

  • It has gained electrons.

  • It has lost neutrons.

  • It has lost electrons.

    
6.

In the diagram, rod R hangs from an insulating thread.




When the positively charged rod Q is brought close to rod R, rod R moves away from rod Q. Which conclusion can be made from this observation?


  • Rod R is charged, but it is not possible to identify the sign of the charge.

  • Rod R must be positively charged.

  • Rod R must be negatively charged.

  • Rod R is uncharged.

    
7.

A plastic rod is rubbed with a cloth.




The rod and the cloth both become charged as electrons move between them. The rod becomes negatively charged. Which diagram shows how the rod becomes negatively charged and shows the final charge on the cloth?


    
8.

A polythene rod is rubbed with a cloth. The rod becomes positively charged because of the movement of charged particles. Which row gives the name of these charged particles, and the direction in which they move?


 
charged
particles
direction of
movement
 
A
electrons
from cloth to rod
 
B
electrons
from rod to cloth
 
C
protons
from cloth to rod
 
D
protons
from rod to cloth
 
    

9.

A man walks across a carpet. He becomes negatively charged by friction with the carpet. What happens as he touches a metal object connected to the Earth?


  • The man gains electrons.

  • The man loses electrons.

  • The man gains protons.

  • The man loses protons.

    
10.

Which quantity is measured in coulombs?


  • charge

  • current

  • electromotive force

  • power

    
11.

Two very light, charged balls P and Q are hung, one above the other, from nylon threads. When a negatively charged plastic sheet is placed alongside them, P is repelled and Q is attracted.




What are the original charges on P and on Q?


 
charge on P
charge on Q
 
A
negative
negative
 
B
negative
positive
 
C
positive
negative
 
D
positive
positive
 
    
12.

Three charged balls, P, Q and R, are suspended by insulated threads. Ball P is negatively charged.




What are the charges on Q and on R?


 
Q
R
 
A
positive
positive
 
B
positive
negative
 
C
negative
positive
 
D
negative
negative
 
    
13.

A polythene rod repels an inflated balloon hanging from a nylon thread. What charges must the rod and the balloon carry?


  • The rod is charged but the balloon is not.

  • The balloon is charged but the rod is not.

  • The rod and the balloon carry like charges.

  • The rod and the balloon carry opposite charges.

    
14.

When a plastic comb is placed next to a small piece of aluminium foil hanging from a nylon thread, the foil is repelled by the comb. Why is this?


  • The comb is charged and the foil is uncharged.

  • The comb is uncharged and the foil is charged.

  • The comb and the foil have charge of opposite signs.

  • The comb and the foil have charge of the same sign.

    
15.

Diagram 1 shows two thin, uncharged strips of plastic.


Diagram 2 shows the same strips after they have been rubbed with a dry cloth.




Which row describes the charge on the strips after rubbing, and the force between the strips after rubbing?


 
charge on strips
force between strips
 
A
opposite
attraction
 
B
opposite
repulsion
 
C
the same
attraction
 
D
the same
repulsion
 
    
16.

A plastic rod is rubbed with a cotton cloth. This process causes the rod and the cloth to become charged. These charges cause a force between the rod and the cloth. Which row compares the charges on the rod and the cloth, and describes the effect of the force between the rod and the cloth?


 
charges on rod
and cloth
effect
 
A
opposite
they attract
 
B
opposite
they repel
 
C
the same
they attract
 
D
the same
they repel
 
    
17.

A student charges a plastic rod by rubbing it with a dry cloth. The rod becomes positively charged as shown in the figure below.




  • State the sign of the charge, if any, on the cloth.

  • State which particles the cloth has gained for it to have this charge.

    
18.

A student rubs two thin plastic strips with a dry cloth. The strips are suspended so that they are free to move. The figure below shows the two plastic strips before and after the student rubs them with the dry cloth.




Explain why the bottom ends of the strips move apart after rubbing.