GCSE Questions: Static Electricity
(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 the water?
A) The positive and the negative charges in the water are attracted to the rod.
B) The positive and the negative charges in the water are repelled by the rod.
C) The negative charge in the water is repelled by the rod and the positive charge is attracted to the rod.
D) The negative charge in the water is attracted to the rod and the positive charge is repelled by the rod.
(b) A company that produces bottles of mouthwash found a problem with its automatic filling system.
As the bottles go towards the filler, the bottles move around on the conveyor belt and become electrostatically charged. This causes the stream of mouthwash to move sideways, 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.
Friction as the bottles rub between the bottles and conveyor beltcauses electrons to transfer onto the bottles.
(ii) What happens to the structure of an atom to change the atom into an ion?
It gains or loses electrons.
(iii) Simply earthing the conveyor belt with a conducting wire would not have solved this problem.
Give a reason why this would not work.
Charge will not (easily) flow off the conveyor belt and it is made of a good insulator (rubber).
[Total 5 marks]