Practise O/L exam questions on Waves and Sound with worked solutions
2021 · Paper II · 5 marks
A sound wave has a frequency of 440 Hz and travels at 340 m/s in air.
(i) Calculate the wavelength of the sound wave.
(ii) Distinguish between a transverse wave and a longitudinal wave. State which type sound is.
(iii) Explain why sound cannot travel through a vacuum.
Show worked solution
(i) λ = v / f = 340 / 440 ≈ 0.77 m
(ii) Transverse wave — particles vibrate perpendicular to the direction of wave travel (e.g. light). Longitudinal wave — particles vibrate parallel to the direction of travel (e.g. sound). Sound is longitudinal.
(iii) Sound requires a material medium (particles) to compress and rarefy. A vacuum has no particles, so sound cannot be transmitted.