A student rubs a perspex rod with a dry woollen cloth. After rubbing, the perspex rod has a positive charge.
State the name of the particles that move between the rod and the cloth when they are rubbed together.
Explain why the woollen cloth is left with a negative charge that is equal in size to the positive charge on the rod.
Figure 1 shows the electric field around a small charged sphere. Two points, P and Q, are marked.
Define what is meant by an electric field.
State whether the charge on the sphere is positive or negative. Give a reason for your answer.
The electric field is stronger at point P than at point Q. Give a reason why the diagram shows this.
A road tanker delivers petrol to a filling station. As the petrol flows through the rubber hose, static charge can build up on the hose.
Charge builds up on the hose because
A protons are transferred from the petrol to the hose
B electrons are transferred by friction between the petrol and the hose
C the hose gains protons from the air
D neutrons are removed from the petrol
State why a spark near the tanker would be dangerous.
Before unloading, the driver connects the tanker to a metal rod buried in the ground. Explain how this prevents a dangerous build-up of charge.
A child rubs an inflated balloon on their hair. The balloon gains electrons from the hair.
State the type of charge on the balloon and the type of charge on the hair after rubbing.
When the balloon is taken away, the individual hairs move apart and stand on end. Explain why.
