Static charge — AQA GCSE Physics
Test yourself on Static charge with AQA GCSE practice questions.
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Static charge explained
Like charges repel: two negative objects push apart, and so do two positive ones.
Read the full explanation
In the standard demonstration a charged polythene rod is brought near an identical charged rod hanging from a thread, and the hanging rod swings away. The reason is that each rod sits in the electric field of the other, and a negative charge in the field of another negative charge is pushed outwards. Repulsion is the more useful test of the two, because attraction also happens between a charged object and an uncharged one, whereas only two like-charged objects repel. That is why the hair on a charged student's head stands up: every hair carries the same sign of charge, so the hairs repel and spread as far apart as they can.
Your focus
- Predict whether two named charged objects attract or repel and give the reason in terms of their charges.
- Explain why repulsion is a better test for a charged object than attraction.
- Describe the hanging rod demonstration and say what its result shows.
Static charge exam tips
Marking Points
- one mark for identifying the force as a force of repulsion
- one mark for the reason that both objects carry the same type of charge
- one mark for repulsion, rather than attraction, being the reliable test for a charged object
- one mark for each hair carrying the same charge when explaining hair standing on end
Examiner Tips
- 💡In tick-box questions with a reason, the reason mark usually depends on the tick, so decide carefully first.
- 💡State the sign of both charges in your reason, not simply that they are charged.
- 💡Remember that repulsion is the only safe test for charge.
Common Mistakes
- giving repulsion as the answer but then giving a reason about opposite charges
- using attraction as proof that an object is charged, when an uncharged object is attracted too
- saying the rods repel because they are both made of plastic
- leaving the reason blank, when the reason mark depends on the first answer being right