Electromagnetic Spectrum: Properties and Uses — AQA GCSE Physics
The electromagnetic spectrum is a continuous range of transverse waves that all travel at the same speed in a vacuum.
Properties of EM waves
Electromagnetic (EM) waves are transverse waves that transfer energy from a source to an absorber. They all travel at the same speed through a vacuum (the speed of light).
They form a continuous spectrum, grouped by wavelength and frequency:
Radio → Microwave → Infrared → Visible light → Ultraviolet → X-rays → Gamma rays (longest wavelength/lowest frequency → shortest wavelength/highest frequency)
Our eyes detect only the narrow visible light band.
Uses of each region
- Radio waves — TV and radio broadcasting, communications.
- Microwaves — cooking, satellite and mobile communications.
- Infrared — heating, cooking, thermal imaging, remote controls, optical fibres.
- Visible light — seeing, photography, fibre-optic communications.
- Ultraviolet — energy-efficient lamps, sun tanning, detecting forged notes.
- X-rays — medical imaging of bones, security scanners.
- Gamma rays — sterilising equipment, treating cancer.
How they are produced and detected
Radio waves can be produced by oscillations in electrical circuits. Changes in atoms and nuclei can produce a range of EM radiation (e.g. gamma rays come from the nucleus).
Exam tips
- All EM waves are transverse and travel at the same speed in a vacuum.
- Learn the spectrum in order (radio → gamma).
- Match each region to its uses.
- Only visible light can be seen by the human eye.