AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER
Uses of electromagnetic waves
Waves · Lesson 9 of 12
Warm-up
Answer each one, then check.
1. Name a type of EM wave.
Radio, microwave, infrared, visible, ultraviolet, X-ray or gamma
2. Which EM waves are ionising?
X-rays and gamma rays (and some UV)
3. What is a satellite?
An object that orbits a planet
4. What is fibre optics?
Thin glass fibres that carry light signals
5. What does a remote control use?
Infrared
Learning Objectives
1. Give uses of radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.
2. Give brief explanations of why each wave is suitable for its use (Higher tier).
Uses Of Em Waves
Electromagnetic waves have many practical applications. Each type is suited to its use by its wavelength and how it interacts with matter.
Radio: TV and radio. Microwaves: satellite communications, cooking. Infrared: heaters, cooking, cameras. Visible: fibre optics. Ultraviolet: lamps, tanning. X-rays and gamma rays: medical imaging and treatment.
Uses of the Electromagnetic Spectrum
|
Each wave suits its use because of its wavelength and energy. |
Icons showing the uses of radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.
Uses and Why They Suit
Higher tier explanations in the last column.
|
Wave |
Uses |
Why suitable |
|---|---|---|
|
Radio waves |
Television and radio |
Long wavelength, so they can travel long distances and diffract round obstacles |
|
Microwaves |
Satellite communications; cooking |
Pass through the atmosphere; absorbed by water molecules to heat food |
|
Infrared |
Heaters, cooking, infrared cameras |
Absorbed by surfaces, warming them; emitted by warm objects |
|
Visible light |
Fibre optic communications |
Reflects along glass fibres by total internal reflection; is not absorbed much |
|
Ultraviolet |
Energy-efficient lamps; sun tanning |
Makes a coating glow with visible light; causes skin to darken |
|
X-rays |
Medical imaging |
Pass through soft tissue but are absorbed by bone |
|
Gamma rays |
Medical treatments and sterilising |
Penetrating; ionising so they kill cells or bacteria |
Why Microwaves for Satellites
|
Explain why microwaves are used for satellite communication. |
1. Penetration
They pass through the atmosphere without being absorbed or reflected much
2. Direction
They can be sent in a narrow beam
3. Result
Signals reach satellites and come back to Earth
Answer: Microwaves can pass through the atmosphere to a satellite and back.
Why X-rays for Bones
|
Explain why X-rays are used to image broken bones. |
1. Soft tissue
Transmits X-rays, so they pass through to the detector
2. Bone
Absorbs X-rays, leaving a shadow
3. Image
The bone shows white or dark on the image
Answer: Bone absorbs more X-rays than soft tissue, so it shows on the image.
Why Gamma Rays for Treatment
|
Explain why gamma rays can be used to treat cancer. |
1. Penetrating
They reach tumours inside the body
2. Ionising
They damage or kill cancer cells
3. Beams
Focused from several directions to limit damage to healthy cells
Answer: Gamma rays penetrate and ionise, killing cancer cells.
Key Ideas
For exam answers.
▸ Match. Link the property of the wave to the use.
▸ Hazard. X-rays and gamma rays must be used carefully.
▸ Energy transfer. Microwave ovens and infrared heaters transfer energy to food or surfaces.
▸ Communication. Radio, microwaves, light carry information.
Key Terms
|
Satellite communication Sending signals to and from satellites, using microwaves. |
Fibre optics Glass fibres that carry light signals. |
|
Medical imaging Making pictures of the inside of the body. |
Radiotherapy Using radiation to treat cancer. |
|
Thermal camera A camera that detects infrared. |
Sterilise Kill bacteria, e.g. using gamma rays. |
Your Task: Match the Wave
10 minutes
|
Match the use to the wave: (a) cooking food quickly (b) remote control (c) checking for broken bones (d) broadcasting TV programmes (e) treating cancer (f) tanning. 1. Name the wave. 2. Say why it suits the job. |
A good answer shows: (a) Microwaves (b) Infrared (c) X-rays (d) Radio waves (e) Gamma rays (f) Ultraviolet.
Can I...?
☐ Give uses of radio waves.
☐ Give uses of microwaves.
☐ Give uses of infrared.
☐ Give uses of visible light.
☐ Give uses of ultraviolet.
☐ Give uses of X-rays.
☐ Give uses of gamma rays.
☐ Explain why each is suitable.
Summary
✓ Radio: TV and radio.
✓ Microwaves: satellites, cooking.
✓ Infrared: heaters, cameras. Visible: fibre optics. UV: lamps, tanning.
✓ X-rays and gamma: medical imaging and treatments.
|
EXAM FOCUS State one use of infrared radiation. (1 mark) Electrical heaters, cooking or infrared cameras. |