Physics (AS & A Level) · May / June 2025 · Paper 13 · Question 30

A ripple tank contains water at a constant depth. A water wave of constant frequency travels towards a gap in a barrier placed in the ripple tank. [diagram of plane waves approaching a gap in a barrier] The gap is made smaller. Which diagram represents the wave before and after the barrier?

1. A[diagram A: plane waves before barrier, short straight wavelets after narrow gap]
2. B[diagram B: plane waves before barrier, slightly curved wavelets after gap]
3. C[diagram C: plane waves before barrier, circular wavelets spreading after gap]
4. D[diagram D: plane waves before barrier, wide circular wavelets spreading after gap]

As printed in the paper