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3.3 Electromagnetic spectrum

Syllabus
0625–2026–2027
Topic
3.3
Level
—

3.3.1—Main regions of the EM spectrum in

  • Know the main regions of the electromagnetic spectrum in order of frequency and in order of wavelength

3.3.2—All EM waves travel at the same high

  • Know: all electromagnetic waves travel at the same high speed in a vacuum

3.3.3—EM spectrum uses: (a) radio waves

  • Describe typical EM spectrum uses: (a) radio waves: radio/TV, astronomy, RFID (b) microwaves: satellite TV, mobile phones, microwave ovens (c) infrared: grills, remotes, intruder alarms, thermal imaging, optical fibres (d) visible light: vision, photography, illumination (e) ultraviolet: security marking, fake banknote detection, sterilising water (f) X-rays: medical scans, security scanners (g) gamma rays: sterilising food/medical equipment, cancer detection/treatment

3.3.4—Harm from excessive EM radiation: (a)

  • Describe harm from excessive EM radiation: (a) microwaves: internal body-cell heating (b) infrared: skin burns (c) ultraviolet: surface-cell/eye damage, skin cancer and eye conditions (d) X-rays/gamma rays: mutation or cell damage

3.3.5—Communication with artificial

  • Know: communication with artificial satellites is mainly by microwaves: (a) some satellite phones use low orbit artificial satellites (b) some satellite phones and direct broadcast satellite television use geostationary satellites

3.3.6—Speed of EM waves in a vacuum is 3.0 ×

  • Know: the speed of electromagnetic waves in a vacuum is 3.0 × 108 m/s and is approximately the same in air

3.3.7—EM radiation: (a) mobile

  • Know communication systems using EM radiation: (a) mobile phones/wireless internet use microwaves because they penetrate some walls and need short aerials (b) Bluetooth uses radio waves because they pass through walls but weaken (c) optical fibres use visible/infrared for cable TV and high-speed broadband because glass transmits them and they carry high data rates

3.3.8—Difference between a digital and

  • Know the difference between a digital and analogue signal

3.3.9—A sound can be transmitted as a

  • Know: a sound can be transmitted as a digital or analogue signal

3.3.10—Benefits of digital signalling

  • Explain the benefits of digital signalling including increased rate of transmission of data and increased range due to accurate signal regeneration

Objective notes

10 learning objectives
ConceptIGCSE Physics