AQA GCSE Physics: Waves

Sound travelling through air is an example of a longitudinal wave, while a ripple on the surface of water and light are examples of transverse waves.

Describe and explain the difference between a transverse wave and a longitudinal wave, referring to the direction of oscillation relative to the direction of energy transfer. Give a named example of each and state one property that is the same for both types of wave. (6 marks)

A radio station broadcasts using radio waves of frequency 100 MHz (which is $100 \times 10^6\ \text{Hz}$100×106 Hz). Radio waves travel through the air at a speed of $3.0 \times 10^8\ \text{m/s}$3.0×108 m/s.

(a) Calculate the wavelength of these radio waves. Use $v = f\lambda$v=fλ. Show your working and give the unit. (3 marks)

(b) A sound wave in air has the same frequency, 100 Hz lower in scale at $100\ \text{Hz}$100 Hz, and travels at $340\ \text{m/s}$340 m/s. Without detailed calculation, state whether its wavelength is longer or shorter than the radio wave's, and give a reason. (1 mark)

A student investigates waves on a stretched string using a vibration generator. They measure the time for 20 complete oscillations and record it as 8.0 s.

(a) Calculate the period of one oscillation. (1 mark)

(b) Calculate the frequency of the wave. Use $f = \dfrac{1}{T}$f=T1​. Show your working and give the unit. (2 marks)

The electromagnetic (EM) spectrum is a continuous family of transverse waves. Part of it is shown, in order:

Group	radio	microwave	infrared	visible	ultraviolet	X-ray	gamma

(a) State how the wavelength changes as you move from radio towards gamma. (1 mark)

(b) Name one group of EM waves used for cooking food and one group used to take images of bones in hospitals. (2 marks)

Ultraviolet (UV) radiation reaches the Earth from the Sun.

Explain one way that over-exposure to ultraviolet radiation can be harmful to the human body, and state why UV is more damaging than visible light. (2 marks)

All waves, including light and sound, transfer energy from one place to another.

State what a wave transfers from one place to another without transferring. (1 mark)