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3.3.2Waves

Uses of Electromagnetic Waves — Cambridge IGCSE Physics 0625 Revision Notes & Topical Questions

5 min read 9 parts Lesson 27 of 35 1 quiz

📚 Cambridge IGCSE Physics 0625 Hub / Topical Revision
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Curriculum Equation Key Wave Speed & Doppler Effect FormulasFast Exam Solution
v = f × λ | f_obs = f × (v ± v_o) / (v ∓ v_s) | T = 1 / f
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Lesson summary

3.3.2 Uses of Electromagnetic Waves — IGCSE PHYSICS notes: Describe the uses of each region of the electromagnetic spectrum.Main use — wireless communicationMicrowave uses — Wi-Fi, radar, mobile phones and satellite communications often assumed to be radioRadio uses — radio and t…

  • Microwave oven
  • Thermal imaging cameras
  • Remote controls
  • Optical fibres
  • Other uses
  • Fluorescence

Part 1 of 8Radio waves and microwaves

Main use
  • Main use wireless communication
Microwave uses
  • Wi-Fi, radar, mobile phones and satellite communications often assumed to be radio
Radio uses
  • Radio uses radio and television transmissions, astronomy and radio frequency identification (RFID)
Microwave oven
  • Microwave oven at very high intensities microwaves heat food

Part 2 of 8Infrared

Emission
  • Emission warm objects emit infrared radiation
Thermal imaging cameras
  • Thermal imaging cameras detect infrared in security, research and medicine
Remote controls
  • Remote controls small infrared LEDs send invisible signals to a receiver on a TV
Optical fibres
  • Optical fibres infrared travels down fibres more efficiently than visible light, so most systems use it
Other uses
  • Other uses electric grills and intruder alarms

Part 3 of 8Visible light

Detection
  • Detection the only part of the spectrum the human eye can see
Uses
  • Uses photography, videography and illumination

Part 4 of 8Ultraviolet

Suntan
  • Suntan the body's way of protecting itself against ultraviolet
Fluorescence
  • Fluorescence substances absorb ultraviolet and re-emit it as visible light, making them glow
Security marking
  • Security marking special ink marks things secretly and bank notes have invisible fluorescent markings
Fluorescent lamps
  • Fluorescent lamps emit visible light by the same principle

Part 5 of 8X-rays and gamma rays

X-rays and gamma rays
X-rays
  • Pass through body tissues but are absorbed by dense parts such as bones
  • Bones leave a shadow on photographic film
Gamma rays
  • Kill cells and living tissue
  • Used in cancer detection and treatment
  • Carefully aimed beams destroy cancer cells
  • Sterilise food, water and medical equipment by killing bacteria

Part 6 of 8Why each wave suits its use

Microwaves
  • Microwaves not refracted, reflected or absorbed by the atmosphere, so satellites can relay signals
Infrared
  • Infrared detected by heat, so it suits imaging and remote controls
X-rays
  • X-rays pass through soft tissue but not bone
Gamma rays
  • Gamma rays highly penetrating and kill cells

Part 7 of 8Summary table

WaveUse
RadioRadio and television, astronomy, RFID
MicrowaveSatellite television, mobile phones, microwave ovens
InfraredGrills, remote controls, intruder alarms, thermal imaging, optical fibres
Visible lightVision, photography, illumination
UltravioletSecurity marking
X-raysMedical imaging
Gamma raysSterilising, medical scanning, cancer treatment

Part 8 of 8More from the specification

1Propagation of radiant energy toward Earth
  • Propagation of radiant energy toward Earth electromagnetic waves travel at light speed across space, delivering solar radiation energy to Earth.
2Analogue
  • Instrument displaying a quantity by pointer position or liquid level on a scale.
3Geostationary
  • Orbiting with a period of 24 h above the equator, so staying above one point.
4Wavelength
  • Distance between a point on one wave and the same point on the next wave
5Analogue signal
  • Signal that varies continuously and can take any value
6Geostationary satellite
  • Satellite orbiting above the equator in 24 hours at 36 000 km
7Artificial satellite
  • A man-made object orbiting a body in space.
8Digital signal
  • Signal that has only two states, 1 and 0

Key terms

TermMeaning
FluorescenceAbsorbing ultraviolet and re-emitting it as visible light
Thermal imagingDetecting infrared to form a picture of warm objects
RadarUse of microwaves to detect objects
RFIDRadio frequency identification using radio waves
SteriliseKill bacteria, for example with gamma rays

Avoid these mistakes

1
Assuming Wi-Fi and mobile phones use radio waves — they use microwaves.
2
Saying X-rays are absorbed equally by all tissue — dense bone absorbs them most.
3
Confusing fluorescence with reflection — the substance absorbs ultraviolet and re-emits visible light.
4
Naming the wave without the use — match each region to a specific use.

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