What this practice covers
These questions are drawn from past CIE 9702 Physics papers and filtered to superposition. 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 superposition, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Taking the node spacing as the wavelength rather than as half of it.
- Saying particles between adjacent nodes are out of phase because their amplitudes differ.
- Saying diffraction changes the wavelength.
- Defining coherent as "in phase" rather than "constant phase difference".
- Swapping a and x in λ = ax/D.
- Forgetting that d = 1/N for a grating, or leaving N in lines per millimetre.
- Saying the central maximum of a grating with white light is a spectrum.
- Saying red is deviated least by a grating, which is true of a prism instead.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Superposition revision notes.