GCSE Physics revision

Uses and applications of electromagnetic waves

Electromagnetic waves

AQA 4.6.2.4

Your specification

AQA student objectives

Learning pathway

ALL 🎯

Give brief explanations why each type of electromagnetic wave is suitable for the practical application.

MOST 🎯🎯

Apply the specified scientific knowledge of uses and applications of electromagnetic waves to a relevant example.

SOME 🎯🎯🎯

Analyse an unfamiliar example of uses and applications of electromagnetic waves using the specified scientific ideas.

Revision summary

Read on screen, then print for Cornell-style active revision.

Radio waves are used to transmit radio signals and terrestrial TV signals (e.g.
Freeview), received via an aerial.
Radio waves are suitable because they can travel long distances before being absorbed by obstacles such as buildings and trees.
Longer wavelength radio waves can diffract (spread out) around hills, allowing signals to reach areas behind obstacles.
Radio waves can reflect off the ionosphere, a layer of charged particles in the atmosphere, enabling transmission over very long distances around the Earth.

1. Radio WavesAQA

Radio waves are used to transmit radio signals and terrestrial TV signals (e.g.
Freeview), received via an aerial.
Radio waves are suitable because they can travel long distances before being absorbed by obstacles such as buildings and trees.
Longer wavelength radio waves can diffract (spread out) around hills, allowing signals to reach areas behind obstacles.
Radio waves can reflect off the ionosphere, a layer of charged particles in the atmosphere, enabling transmission over very long distances around the Earth.

Microwaves are used to heat food because water molecules in food absorb microwave energy, causing the food's temperature to rise.
Microwaves are used to communicate with satellites in space because they can pass through the Earth's atmosphere without being reflected or refracted.

Infrared is emitted by electrical heaters and used in ovens to cook food, as its energy is easily absorbed by the surface of objects.
When infrared from a heater is absorbed by objects in a room, it warms the room by transferring energy to those objects.
Infrared cameras detect heat emitted by objects and are used, for example, to identify heat losses from buildings.

3. Infrared RadiationAQA

Infrared is emitted by electrical heaters and used in ovens to cook food, as its energy is easily absorbed by the surface of objects.
When infrared from a heater is absorbed by objects in a room, it warms the room by transferring energy to those objects.
Infrared cameras detect heat emitted by objects and are used, for example, to identify heat losses from buildings.

A key use of visible light is communication via optical fibres, which are thin strands of glass that carry pulses of light.
Optical fibres are used to transmit telephone and cable TV signals, carrying large amounts of information due to visible light's short wavelength.

Ultraviolet light is produced inside energy-efficient light bulbs, where its energy is absorbed by the bulb's internal coating and converted into visible light, using less energy than a conventional bulb.
Ultraviolet is used in tanning beds for sun tanning; however, overexposure increases the risk of skin cancer and causes premature skin ageing.

5. Ultraviolet RadiationAQA

Ultraviolet light is produced inside energy-efficient light bulbs, where its energy is absorbed by the bulb's internal coating and converted into visible light, using less energy than a conventional bulb.
Ultraviolet is used in tanning beds for sun tanning; however, overexposure increases the risk of skin cancer and causes premature skin ageing.

X-rays are used for medical imaging because they are highly penetrative and pass through soft body tissue but are absorbed by denser material such as bone, making broken bones visible.
X-rays can also be used in medical treatments, such as targeting and destroying cancerous cells.

Gamma rays are used in medical imaging to detect cancers, as they are highly penetrative and can pass through body tissue.
Gamma rays are also used in medical treatment to destroy cancerous tumours, similar to the use of X-rays in radiotherapy.

Electromagnetic waves with shorter wavelengths (such as visible light and ultraviolet) carry more energy and can transmit more information per wave.
The suitability of each type of electromagnetic wave for its use depends on its specific properties, such as wavelength, energy, and ability to penetrate or be absorbed by different materials.

8. Key Comparisons Across the SpectrumAQA

Electromagnetic waves with shorter wavelengths (such as visible light and ultraviolet) carry more energy and can transmit more information per wave.
The suitability of each type of electromagnetic wave for its use depends on its specific properties, such as wavelength, energy, and ability to penetrate or be absorbed by different materials.