Paper 1: Measuring Wave Velocity

Question 1

How do you calculate the speed of sound in air using an echo?

Answer 1

1) measure distance from source of sound to reflective surface (wall)
2) measure time intervals (with stopwatch) between originals sound produced and echo heard
3) use distance / time to calculate speed of sound in air

Question 2

How do you calculate the speed of sound in air using microphones and oscillopes?

Answer 2

1) set up 2 microphones on in front of other at different distances in a straight line from a loud speaker
2) set frequency of sound from loudspeaker to known, audible value
3) display 2 waveforms on the oscilloscope. measure the distance between the microphones
4) move the microphones apart so that the waveforms move apart by 1 wavelength
5) calculate speed sound using equation: frequency x wavelength