1) 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?

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

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

3) A stationary longitudinal wave is set up in a pipe.

In the diagrams below, the length of each arrow represents the amplitude of the motion of the air molecules, and the arrow head shows the direction of motion at a particular instant.

Which diagram shows a stationary wave in which there are two nodes and two antinodes?

4) A stationary wave is produced by two loudspeakers emitting sound of the same frequency.

When a microphone is moved between X and Y, a distance of 1.5 m, six nodes and seven antinodes are detected.

What is the wavelength of the sound?

5) The three waves shown in each diagram have the same amplitude and frequency but differ in phase.

They are added together to give a resultant wave.

In which case is the resultant wave zero?