Measuring Waves

Measuring Sound Waves

The following experiment can be used to measure the speed of sound: 

1. Set up the oscilloscope so that each of the microphones are connected separately. 
2. Turn on the signal generator and make a note of the frequency, f that you have chosen.
3. Begin with both microphones next to the speaker. The waves on the oscilloscope should line up, as shown in the diagram.
4. Move one microphone away from the other slowly. As it moves away, the waves on the oscilloscope will change. 
5. When the waves on the oscilloscope line-up again, stop moving the microphone. The distance between the microphones is the wavelength, \bold{\lambda} of the sound. 
6. Measure the distance between the two microphones using a meter rule. 
7. Calculate the speed of sound using \bold{\text{v}=\text{f}\lambda}.

Required Practical

Measuring the Speed of Water Waves

This is a simple method for measuring the wavelength and speed of water waves. From this, you can calculate the frequency and period of the waves. 

Doing the experiment

1. In a darkened room, set up the experiment as shown in the diagram.
2. Switch on the signal generator so that the dipper produces waves.
3. Using the meter ruler, measure the distance between the shadows of the waves on the screen.
4. Choose two points on the screen and measure the distance between them. 
5. Using a stopwatch, measure the time taken for a wave to travel between the two points.  
6. Calculate the speed of the wave using \text{speed}=\dfrac{\text{distance}}{\text{time}}.