The emphasis in this practical should be on the different methods needed to measure
these quantities for the different waves. For water waves, the speed, frequency and
wavelength can all be measured separately, but the speed of sound in a solid is too fast
to be measured by simply measuring distance and time. Here, the speed is calculated
using the measurements made of frequency and wavelength.
Questions you could ask to enhance learning and focus your students on
important aspects of the practical:
- Waves can be transverse or longitudinal. What type of wave is (a) a water wave on the surface of the water in a ripple tank? (b) a sound wave in a metal rod?
- How would you measure the speed of sound in air?
- How would you measure the speed of water waves in a ripple tank?
- Why can you not measure the speed of sound waves in a metal rod in the same way?
- Is it possible to measure the speed of light?
- Adjusting the components of a ripple tank to give parallel water waves of measurable wavelength
- Measuring the wavelength of a water wave in a ripple tank
- Measuring the speed of a wavefront (wave crest)
Maths skills:
- Substituting measured values into the equation relating speed, distance and time
- Substituting measured values into the equation relating speed, wavelength and frequency
- Changing the subject of an equation