Required practical

Measure the frequency, wavelength & speed of waves in a solid

There are many different ways that the speed of waves in a solid can be measured. One method involves the use of a vibration generator.

A piece of string hanging over a wooden bridge. There is a weight hooked onto the on the end of the string. At the other end is a vibration generator.

Aim of the experiment

To measure the frequency, wavelength and speed of waves in a string.

Method

  1. Attach a string or cord to a vibration generator and use a 200 gram (g) hanging mass and pulley to pull the string taut as shown in the diagram. Place a wooden bridge under the string near the pulley.
  2. Switch on the vibration generator and adjust the wooden bridge until stationary waves can be clearly observed.
  3. Count the number of loops. Divide the length of the oscillating part of the string by this number of loops to get the length of one loop. The length of each loop is half a wavelength, so double this to get the length of one wavelength.
  4. The frequency is the frequency of the power supply.
  5. Calculate the speed of the waves using: wave speed = frequency × wavelength.

Example results table

Number of half wavelengthsLength of X half wavelengths cmWavelength cmFrequency HzWavespeed cm/s
..............................

Risks & hazards

HazardConsequenceControl Measures
Cord snappingDamage to eyesEye protection / safety screen