Experiment 1 To investigate the variation of frequency in a stretched string with length.

Apparatus Tuning fork Sonometer Paper rider

Method

• Leaving the tension unchanged, place a paper rider on the centre of the wire.

• Strike a tuning fork and touch the wire at a bridge.

• Move the other bridge until the paper rider falls off.

• Note the frequency on the fork and the length between the bridges.

The Results

• Plot a graph of frequency against 1/length.

• The graph is a straight line through the origin showing that frequency is inversely proportional to length.

Frequency Hz 256 288 320 341.3

384 480 Length m 1/length 0.57

0.499

0.449

0.424

0.377

0.305

Precautions

1. Place the paper rider in the centre of the wire.

2. Keep the tension fixed as there can only be 2 variables.

A wee sum on the experiment

The tension on the string is 38N.

1. From the graph find the length that has a fundamental frequency of 300Hz.

2. Find the mass of this length of wire.

Experiment 2 To investigate the variation of frequency in a stretched string with tension.

Apparatus

Tuning fork Newton balance Sonometer Paper rider

Method

• Leaving the length unchanged, place a paper rider on the centre of the wire.

• Strike a tuning fork and touch the wire at a bridge.

• Use the key to adjust the tension until the paper rider falls off.

• Note the frequency on the fork and the tension on the newton balance.

The Results

• Plot a graph of frequency against

Tension

• The graph is a straight line through the origin showing that frequency is proportional to the root of the tension.

Frequency Hz Tension N

Tension

Precautions

1. Place the paper rider in the centre of the wire.

2. Keep the length fixed as there can only be 2 variables.