Required Practical 8: Waves
Investigate the suitability of apparatus to measure the frequency, wavelength and speed of waves in a
ripple tank and waves on a stretched string
Part 1 Waves in a ripple tank
Equipment
 Ripple tank and accessories
 Low voltage power supply
 Metre ruler
 Stop watch
Method
 Set up the ripple tank as shown, with water
of a depth of 5 mm and the wooden rod just
touching the surface of the water.
 Switch on the overhead lamp and electric
motor.
 Adjust the equipment to view clear, slow
waves on the screen.
 Use the available equipment to measure the
wavelength and period of the waves.
 Calculate the frequency and speed of the
waves.
Safety!
Mop up spills immediately.
AT 4
Screen
Mirror
Calculation of speed
Wavelength measurement
Frequency measurement
Speed calculation
Write –up: Write this up neatly in your book
1. How was the wavelength measured? What did you do to make this as accurate as possible?
2. How was the frequency measured? What did you do to make this as accurate as possible?
3. What errors do you think were encountered in this experiment?
Part 2 Waves on a string
Equipment
 Vibration generator
 Power supply with variable frequency
(signal generator)
 String
 Set of 100g masses and hanger
 Wooden bridge
 Pulley on a clamp
 Metre rule
Safety!
The vibrating string may snap
and damage eyes, so safety
glasses must be worn.
AT 4
Method
 Set up the apparatus as shown.
 Switch on the vibration generator so that the string vibrates.
 Adjust either the tension in the string (by changing the number of masses), the length of the string
(by moving the wooden bridge), or the frequency on the signal generator.
 Use the available equipment to measure the wavelength of the waves and note down the
frequency from the signal generator.
 Calculate the speed of the waves.
Results and calculation of speed
Wavelength (m)
Frequency (Hz)
Speed (m/s)
Write –up: Write this up neatly in your book
1. How was the wavelength measured? What did you do to make this as accurate as possible?
2. What errors do you think were encountered in this experiment?
Possible Extension
What effect does the tension in the string have on the speed of the waves on the string?