34
Static
TopicElectricity
Header
1 This question is about the electrical properties of different materials.
a) State what is meant by an electrical insulator.
............................................................................................................................................................
[1]
b) Complete the table below.
[2]
Material Electrical conductor? Electrical insulator?
Glass No Yes
Water Yes No
Plastic
......................... .........................
Copper
......................... .........................
[Total 3 marks]
PAPER 2
2 A student does some experiments to study static electricity. He uses a cloth
duster to rub a rubber balloon. The balloon gains an electrostatic charge.
a) Explain, in terms of charge movement, how the balloon becomes positively charged.
............................................................................................................................................................
............................................................................................................................................................
[2]
b) Describe an experiment that could be used to show that the balloon has an electrostatic charge.
............................................................................................................................................................
............................................................................................................................................................
............................................................................................................................................................
[2]
c) The balloon has a charge of 1.5 mC. What charge does the cloth used to rub it have?
Give a reason for your answer.
............................................................................................................................................................
............................................................................................................................................................
[2]
[Total 6 marks]
Section 2 — Electricity
35
PAPER 2
3 A Van de Graaff generator is a machine which is used to generate static electricity. A student uses
one type of Van de Graaff generator in class and writes the following description of how it works.
top comb
+ + + metal
++ + dome
+ + + The bottom comb is positively charged
+ +
+ + and attracts electrons away from the
+ + + rubber belt.
roller +
+
+ +
+
+ + + The rubber belt loses electrons and
+ +
+
+
+
+ + becomes positively charged.
+
moving As the positive charge on the belt passes
+
positive
+
+ rubber the top comb, electrons are attracted
charge
+
+
+
belt from the metal dome onto the belt.
+
The metal dome loses electrons and
+
motor-
bottom
+
driven builds up a positive static charge.
+
comb
+
roller
+
source of –
high voltage
a) Explain why the belt is made from rubber.
............................................................................................................................................................
............................................................................................................................................................
[2]
b) Explain why the top comb needs to be made from a conductor.
............................................................................................................................................................
[1]
c) Explain why electrons are attracted from the metal dome to the belt.
............................................................................................................................................................
[1]
d) Tiny pieces of paper are scattered onto the dome of the Van de Graaff generator. The pieces of
paper appear to ‘jump’ off the dome as soon as they touch the surface. Suggest why this happens.
............................................................................................................................................................
............................................................................................................................................................
............................................................................................................................................................
[2]
[Total 6 marks]
Score:
15
Section 2 — Electricity
37
2 A tall building is fitted with a lightning rod, made from a conductor, that safely directs
charge to earth when the building is struck by lightning. Explain how lightning is caused.
............................................................................................................................ Lightning rod
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[2]
[Total 2 marks]
Earth
3 When refuelling a vehicle, fuel flows out of a fuel nozzle and into the vehicle’s fuel tank.
nozzle
fuel metal fuel tank
a) Explain why it is dangerous if static charge is allowed to build up during this process.
............................................................................................................................................................
............................................................................................................................................................
[2]
b) Give two safety measures that can be taken to reduce the build-up of static charge when fuelling.
1. .......................................................................................................................................................
............................................................................................................................................................
2. .......................................................................................................................................................
............................................................................................................................................................
[2]
[Total 4 marks]
Score:
15
Section 2 — Electricity
