Edexcel GCSE Combined Science: Physics: Waves and the Electromagnetic Spectrum

The electromagnetic (EM) spectrum is a continuous spectrum of waves. Different parts of the spectrum are used in everyday life, but some can be harmful to the human body.

Describe the electromagnetic spectrum, and explain how the properties of different EM waves make them suitable for particular uses while also making some of them dangerous. In your answer you should refer to at least three named regions of the spectrum, including at least one use and at least one danger. (6 marks)

A student uses a signal generator and a loudspeaker to produce a sound wave that travels through the air. The sound wave has a frequency of 170 Hz. The speed of sound in air is 340 m/s.

(a) Calculate the wavelength of the sound wave. Use the wave equation $v = f\lambda$v=fλ. Show your working and give the unit. (2 marks)

(b) Calculate the period of the sound wave. Use the equation $T = \dfrac{1}{f}$T=f1​. Show your working and give the unit. (2 marks)

Water waves in a ripple tank travel across the surface of the water. One particular wave has a wavelength of 0.040 m and a frequency of 5.0 Hz.

(a) Calculate the speed of the water wave. Use the wave equation $v = f\lambda$v=fλ. Show your working and give the unit. (2 marks)

(b) Water waves are an example of a transverse wave. State one difference between a transverse wave and a longitudinal wave. (1 mark)

A radio station broadcasts using radio waves that travel through the air at a speed of 3.0 × 10⁸ m/s. The radio waves have a wavelength of 300 m.

(a) Calculate the frequency of the radio waves. Use the wave equation $v = f\lambda$v=fλ. Show your working and give the unit. (2 marks)

(b) State one use of infrared radiation. (1 mark)

A ray of light travels from air into a glass block. As it crosses the boundary, the light refracts (changes direction).

Explain why the ray of light changes direction as it passes from air into the denser glass. (2 marks)

The electromagnetic spectrum is arranged in order of frequency and wavelength.

Name the part of the electromagnetic spectrum that has the highest frequency (and the shortest wavelength). (1 mark)