Properties of Electromagnetic Waves
- Visible light is just one part of a much bigger spectrum: The Electromagnetic Spectrum
- All electromagnetic waves have the following properties in common:
- They are all transverse waves
- They can all travel in a vacuum
- They all travel at the same speed in a vacuum (free space) — the speed of light 3 × 108 ms-1
- The speed of light in air is approximately the same
Oscillating electric and magnetic fields in an electromagnetic wave
- These transverse waves consist of electric and magnetic fields oscillating at right angles to each other and to the direction in which the wave is travelling (in 3D space)
- Since they are transverse, all waves in this spectrum can be reflected, refracted, diffracted, polarised and produce interference patterns
Uses of electromagnetic waves
- Electromagnetic waves have a large number of uses. The main ones are summarised in the table below
Tables of Electromagnetic Waves and their Uses
WAVE | USE |
Radio | Communication (radio and TV) |
Microwave |
Heating food Communication (WiFi, mobile phones, satellites) |
Infrared |
Remote controls Fibre optic Communication Thermal imaging (medicine and industry) Night vision Heating or cooking things Motion sensors (for security alarms) |
Visible | Seeing and taking photographs/videos |
Ultraviolet |
Security marking (fluorescence) Fluorescent bulbs Tanning beds |
X Rays | X-ray images (medicine, airport security, and industry) |
Gamma Rays |
Sterilising medical instruments Treating cancer |
Exam Tip
You will be expected to recall the common properties of all electromagnetic waves in an exam question, however the speed of light will be given on the data sheet.