PhysicsCode 5054
Electromagnetic spectrum
What this topic asks you to be able to do
- Know the main regions of the electromagnetic spectrum, ordered both by frequency and by wavelength
- Know that all electromagnetic waves travel at 3.0 × 108 m/s in (a) a vacuum, and that in (b) air this speed is roughly equal to the vacuum value
- Describe the part each of the following regions plays in the applications given: (a) radio waves – communicating by radio and television, and astronomy (b) microwaves – microwave ovens, Bluetooth, mobile (cell) phones, television by satellite (c) infrared – thermal imaging, intruder alarms, remote controllers, optical fibres, electrical appliances in the home (d) visible light – seeing, and photography (e) ultraviolet – sterilising water, marking for security, spotting counterfeit bank notes (f) X-rays – imaging for medical purposes in hospitals, security scanners, killing cancerous cells, engineering uses such as finding cracks in metal (g) gamma rays – medical treatment that detects and kills cancerous cells, sterilising food and medical equipment, engineering uses such as finding cracks in metal
- Describe the harm electromagnetic radiation can do, including: (a) too much exposure heating soft tissues and causing burns (b) the ionising effects of ultraviolet, which can lead to skin cancer and cataracts, and of X-rays and gamma rays, which can lead to cell mutation and cancer