Superposition, Interference & Stationary Waves - exam practice

The frequency of the first harmonic of a standing wave on a wire is 𝑓. The length of the wire and tension in the wire are both doubled.

What is the frequency of the first harmonic as a result?

The diagram shows a string stretched between two fixed points O and R which are 120 cm apart.

P and Q are points on the string.

OP = 30 cm

OQ = 90 cm

At a certain frequency the string vibrates at its first harmonic.

P and Q oscillate in phase.

The frequency is gradually increased.

What is the next harmonic at which P and Q will oscillate in phase?

Stationary waves are set up on a rope of length 1.0 m fixed at both ends.

Which statement is not correct?

The frequency of the first harmonic of a wire fixed at both ends is 300 Hz.

The tension in the wire is now doubled.

What is the frequency of the first harmonic after this change?

The fundamental frequency f is the lowest frequency heard when a stretched string is vibrating.

The string is now lightly touched one third of the way along its length.

What is the lowest frequency heard?

A uniform wire, fixed at both ends, is plucked in the middle so that it vibrates at the first harmonic as shown.

What is the phase difference between the oscillations of the particles at P and Q?

When the light from two lamps falls on a screen, no interference pattern can be obtained.

Why is this?

Ships have been damaged by water waves with large amplitudes. These waves could have been formed by adding the displacements of smaller waves.

Which term describes this phenomenon?

This question is about progressive waves and stationary waves.

Which statement is not correct?

This question is about a progressive wave and a stationary wave.

Which statement is correct?