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Year 11 - Science

Light and colour

Electromagnetic waves

Unit Summary

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.

Lesson Summary

You will learn to describe what is different about light of different colours and explain the apparent colour of objects when illuminated with different colours of light.

Key Notes

  • The different colours of light are electromagnetic waves with different frequencies and wavelengths.
  • A triangular prism can produce a colour spectrum from white light, showing it is a mixture of all visible wavelengths.
  • From red to violet in the spectrum, frequency increases and wavelength decreases. Higher frequencies refract further.
  • Opaque objects transmit no incident light. Their colour depends on which wavelengths of incident light are reflected.
  • Colour filters only transmit some wavelengths. The filter colour depends on the transmitted wavelengths.

Vocabulary To Learn

  • electromagnetic wave: Electromagnetic waves are ripples/oscillations in the invisible electric and magnetic fields that are all around us.
  • frequency: The frequency of a wave is the number of oscillations that occur per second.
  • wavelength: The wavelength of a wave is the distance between one point on a wave and the same point on the next wave.
  • refract: Waves are said to refract when they change direction upon entering a new medium.
  • opaque: An object is opaque if no light is transmitted through it.

Common Mistakes To Avoid

  • Pupils assume that the colours of light will mix in the same way that paints mix.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

The different colours of light are electromagnetic waves with different frequencies and wavelengths. A triangular prism can produce a colour spectrum from white light, showing it is a mixture of all visible wavelengths.

2. Define this scientific word and use it in context. 'electromagnetic wave'

Electromagnetic waves are ripples/oscillations in the invisible electric and magnetic fields that are all around us. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: Pupils assume that the colours of light will mix in the same way that paints mix. Correction: Make it explicit in your teaching that the primary colours of light (red, green and blue) are different, and mix differently, to the primary colours of paint that pupils may have been taught elsewhere (e.g. red, yellow and blue).

More Lessons In This Unit

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