1) The diagram shows a stationary wave on a string at two instants of maximum vertical displacement.

The frequency of the wave is 12 Hz.

What is the speed of the wave?

2) Where, in a standing wave, do the vibrations of the medium occur?

3) Source S emits microwaves with constant amplitude. The microwaves hit a metal screen P and are reflected. A stationary wave is formed between S and P. The wavelength of the microwaves is much smaller than the distance between S and P.

A detector Q is moved at a slow, constant speed from S to P.

What happens to the amplitude of the signal detected by Q?

4) The diagram represents the pattern of stationary waves formed by the superposition of sound waves from a loudspeaker and their reflection from a metal sheet (not shown).

W, X, Y and Z are four points on the line through the centre of these waves.

Which statement about these stationary waves is correct?

5) The diagram represents a stationary wave on a stretched string.

What is represented by point P and by the length x?