GCSE Physics · AQA 8463 · Topic 4.6.2
Electromagnetic waves
Key points
- Electromagnetic waves are transverse and travel at the same speed (about m/s) in a vacuum.
- In order of decreasing wavelength: radio, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays. Frequency and energy increase in the same order.
- Refraction is a change of direction when a wave changes speed at a boundary. Light bends towards the normal entering a denser medium like glass.
- Uses: radio (TV and radio), microwaves (satellites, cooking), infrared (heaters, cameras), visible (fibre optics), UV (tanning, energy-efficient lamps), X-rays and gamma (medical imaging and treatment).
- Hazards: UV can age skin and cause cancer; X-rays and gamma rays are ionising and can cause mutations.
- (Separate physics) Lenses: convex lenses form real or virtual images; magnification = image height ÷ object height. Objects look coloured because of which wavelengths they reflect.
Topic notesPremium
Radio, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays are one family of waves. They behave alike, but their different wavelengths give them very different uses and dangers. This sub-topic also covers lenses and…
Unlock the full notes with Premium
Premium includes full topic notes, the paper generator, self-quizzes and progress tracking.
Practise this topicPremium
Premium members can generate an exam-style paper with a mark scheme, or take a quick quiz, on Electromagnetic waves.