determine waves

Question 1

Method for ripple tank

Answer 1

Set up the ripple tank as shown in the diagram with about 5 cm depth of water.
Adjust the height of the wooden rod so that it just touches the surface of the water.
Switch on the lamp and motor and adjust until low frequency waves can be clearly observed.
Measure the length of a number of waves then divide by the number of waves to record wavelength. It may be more practical to take a photograph of the card with the ruler and take measurements from the still picture.
Count the number of waves passing a point in ten seconds then divide by ten to record frequency.
Calculate the speed of the waves using: wave speed = frequency × wavelength.

Question 2

measuring waves in solid

Answer 2

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.
Switch on the vibration generator and adjust the wooden bridge until stationary waves can be clearly observed.
Measure the length of as many half wavelengths (loops) as possible, divide by the number of half wavelengths (loops). This is half the wavelength, doubling this gives the wavelength.
The frequency is the frequency of the power supply.
Calculate the speed of the waves using: wave speed = frequency × wavelength.