Paper 3: Required practical 1 - Stationary waves on a string

Question 1

What piece of apparatus can be used to generate a wave in a piece of string?

Answer 1

Vibration generator, driven by a signal generator

Question 2

What piece of apparatus can be used to alter the length of string that is oscillating?

Answer 2

A bridge (triangular prism shaped object) can be moved along the length of the string to alter the length of the oscillating region

Question 3

Why should the signal generator be operated for several minutes before use?

Answer 3

The generator needs time for the frequency to stabilise

Question 4

In this experiment the string is tied to a clamp stand, what safety precaution should be taken?

Answer 4

A counterweight/g clamp should be used to produce a counteracting moment that prevents the stand from toplpling over

Question 5

How can tension in the string be varied?

Answer 5

Attaching a mass hanger/ more mass to the end of it

Question 6

What safety precaution should be taken when using mass hangers?

Answer 6

Place a padded bucket below the hanger

Question 7

How can you measure the mass per unit length of a piece of string?

Answer 7

Measure the mass of a suitably long piece of string using a mass balance and then divide this by the string’s length

Question 8

What is the advantage of using a long piece of string when measuring the mass per unit length?

Answer 8

The longer the piece, the lower the percentage uncertainty in the measurement

Question 9

When plotting the graph of 1/f against L for a wave’s fundamental frequency, how can the wave speed be determined?

Answer 9

The gradient of the graph will be 1/fL
Wave speed is given by 2fL so is 2/gradient