What this practice covers
These questions are drawn from past CIE 9702 Physics papers and filtered to electric fields. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on electric fields, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Defining electric field strength as force per unit charge without the word positive, so the direction is undefined.
- Forgetting that the force on a negative charge is opposite to the field direction.
- Measuring r from the surface of a charged sphere rather than from its centre.
- Adding electric fields as though they were scalars. Fields are vectors; potentials are scalars.
- Confusing a point of zero field with a point of zero potential. They are different places.
- Assuming V and E fall off with distance in the same way. V goes as 1/r, E as 1/r².
- Using E = ΔV/Δd for the field of a point charge, where the field is not uniform.
- Leaving the plate separation in millimetres in E = ΔV/Δd.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Electric fields revision notes.