Use of radio waves.
television and radio signals.
Why are radio waves suitable for their use?
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they can travel long distances through air
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they have a longer wavelength, which means they can bend around obstructions to allow detection of signals when not in line of sight.
Hazards of radio waves.
They can penetrate the body and cause internal heating.
Use of microwaves.
satellite communications and cooking food.
Why are microwaves suitable for their use?
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they can pass through the Earths atmosphere to reach satellites.
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they can penetrate into food and are absorbed by water molecules in food, heating it.
Hazards of microwaves.
They can penetrate the body and cause internal heating.
Use of infrared.
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electrical heaters
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cooking food
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infrared cameras
Why is infrared suitable for its use?
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all hot objects emit infrared waves - sensors can detect these and turn them into an image.
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can transfer energy quickly to heat rooms and food.
Hazards of infrared.
They can damage or kill skin cells due to heating.
Use of visible light.
Fibre optic communications.
Why is visible light suitable for its use?
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short wavelength means visible light carries more information.
Hazards of visible light
It can damage the retina.
Use of ultraviolet (UV).
Energy efficient lights and artificial sun tanning.
Why is ultraviolet (UV) suitable for its use?
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carries more energy than visible light.
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some chemicals inside light bulbs can absorb UV and emit visible light.
Hazards of ultraviolet (UV).
can cause damage to skin cells, causing skin to age prematurely and increasing the risk of skin cancer, and cause blindness.
Use of X-rays and gamma rays.
medical imaging and treatments.
Why are X-rays and gamma rays suitable for their use?
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they can pass easily through flesh, but not denser materials like bone.
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high doses kill living cells, so can be used to kill cancer cells - gamma rays can also be used to kill harmful bacteria.
Hazards of X-rays and gamma rays.
They are a form of ionising radiation - can damage or kill cells, cause mutation of genes, and lead to cancers.
