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3.3 Electromagnetic spectrum
1 Know the main regions of the electromagnetic spectrum in order of frequency and in order of wavelength
2 Know that the speed of all electromagnetic waves in:
(a) a vacuum is 3.0 × 108m/s
(b) air is approximately the same as in a vacuum
3 Describe the role of the following components in the stated applications:
(a) radio waves – radio and television communications, astronomy
(b) microwaves – satellite television, mobile (cell) phone, Bluetooth, microwave ovens
(c) infrared – household electrical appliances, remote controllers, intruder alarms, thermal imaging, optical
fibres
(d) visible light – photography, vision
(e) ultraviolet – security marking, detecting counterfeit bank notes, sterilising water
(f) X-rays – hospital use in medical imaging, security scanners, killing cancerous cells, engineering
applications such as detecting cracks i
