3.3 — Electromagnetic spectrum

Core

3.3.1 — Know main regions of EM spectrum in order of frequency and wavelength
3.3.2 — Know that all EM waves travel at the same high speed in a vacuum

3.3.3 — Know speed of EM waves in vacuum is 3.0×10^8 m/s and approximately the same in air
3.3.4 — Describe uses of EM waves: radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays
3.3.5 — Describe harmful effects of excessive exposure to EM radiation (microwaves, IR, UV, X-rays, gamma)
3.3.6 — Know communication with artificial satellites is mainly via microwaves, including geostationary satellites
3.3.7 — Know many communication systems rely on EM radiation: mobile phones, Bluetooth, optical fibres
3.3.8 — Know difference between digital and analogue signals
3.3.9 — Know that sound can be transmitted as digital or analogue signals
3.3.10 — Explain benefits of digital signalling: higher data rates, increased range due to regeneration