Key learning points

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

Keywords

• 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 misconception