Electromagnetic waves are oscillations/ripples in electric and magnetic fields.

The frequency of a wave gives the number of oscillations that occur per second.

A spectrum is a continuous range or scale.

Refraction is when waves enter a new material and change direction.

Anything that is emitted (given out) from a system and transfers energy away from that system can be called radiation.

Dispersion of light and electromagnetic radiation

Combined science

In A-level physics, some pupils will build on this knowledge to learn about the photon model of electromagnetic radiation and the use of electromagnetic radiation for collecting evidence about the universe or for generating images of the inside of a human body.

In the Measuring waves unit, pupils learnt about the measurable features of a wave, the relationship between them and the wave equation.

This unit explores reflection, refraction, and lenses using ray diagrams. It covers the electromagnetic spectrum, light as a wave, absorption, transmission, and practical uses. Emphasis is on risks, temperature balance, data presentation, and unit conversions.

Electromagnetic waves

Which of the following colours of light has the highest frequency?

violet, because its speed changes the most

violet, because its speed changes the least

White light is split into its separate colours by this triangular prism as some colours (frequencies) of light are refracted more than others. Which is refracted the most at each boundary, and why?

A pupil makes waves on a rope. The speed of the waves is fixed by the properties of the rope, but the pupil can change the frequency. What happens to the wavelength if the frequency increases?

Put these electromagnetic waves in order of frequency, from lowest to highest.

Security pen ink can only be seen when this is shone onto it.

This is used to transmit television signals over long distances.

This is used to make images of a patient’s bones in hospital.

Match each type of electromagnetic radiation with one of its uses.

All electromagnetic radiation made by humans is harmful.

All naturally-occurring electromagnetic radiation is harmless.

The Sun emits electromagnetic radiation in all seven frequency ranges.

The Sun emits only visible light, infrared radiation and ultraviolet radiation.

Which of the following statements is correct?

the distance from one crest to the next crest.

sometimes to the left and sometimes to the right

sometimes upwards and sometimes downwards

A pupil draws a transverse wave on a piece of paper. The direction of wave travel is from left to right. 
Which of the following describes how each part of the medium moves as the wave passes through?

the height of a wave, from its centre line to a crest

the depth of a wave, from its centre line to a trough

the distance between one wave crest and the next wave crest

the distance between one wave trough and the next wave trough

Which of the following describes the wavelength of a wave?

the distance between one wave crest and the next

the number of seconds it takes for a wavelength to pass a point

the number of wavelengths travelling past a point each second

Which of the following describes the frequency of a wave?

Which of the following is the wave equation?

towards the normal, because the light speeds up.

towards the normal, because the light slows down.

away from the normal, because the light speeds up.

away from the normal, because the light slows down.

When a light ray travels from air to glass (and is not moving at right angles to the boundary), the ray bends …

This lesson will be removed by end of Summer Term 2025.

Dispersion of light and electromagnetic radiation

Lesson outcome

This lesson will be removed by end of Summer Term 2025.