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
Length m
256
288
320
341.3
384
480
0.57
0.499
0.449
0.424
0.377
0.305
1/length
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
Newton
balance
Tuning fork
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.