1
Q
How can you generate sounds with a specific frequency? What can you then use two microphones and an oscilloscope to do?
A
attach a signal generator to a speaker
find the wavelength of the generated sound waves
2
Q
describe the steps to use an oscilloscope to measure the speed of sound
A
- Set up the oscilloscope so the detected waves at each microphone are shown as separate waves
- start with both microphones next to the speaker, the slowly move one away until the two waves are aligned on the display but have moved exactly one wavelength apart
- measure the distance between the microphones to find one wavelength
- calculate the speed of the sound waves passing though the air - the frequency is whatever you set the signal generator to
- speed of sound in air is around 330m/s so check your results roughly agree
3
Q
Describe how to measure the speed of water ripples using a lamp
A
- attach a signal generator to the dipper of a ripple tank and create water waves at a set frequency and dim the lights
- use lamp to see wave crests on the screen, make sure the size of the shadows are the same as the waves
- measure the distance between shadow lines that are 10 wavelengths apart using a ruler, then divide by 10 to find the average wavelength
- calculate wave speed
4
Q
describe the experiment to use the wave equation for waves on strings
A
- on the bench, attach a signal generator to the vibration transducer which is attached to the string, which is attached by the pully, with mass hanging off the end
- turn on the generator and transducer, the string will vibrate
- adjust the frequency of the generator until there’s a clear wave, the freq needed will depend on the length of the string between the pulley and transducer, and the masses used
- measure the wavelength (4-5 then divide to find mean half wavelength then double to find full wavelength)
- freq is whatever generator is set to
- calculate wavespeed
