Light, infrared, microwaves and radio waves

What is the range of the wavelength of radio waves?
1m-100km
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What are radio waves used for in communication?
To communicate with submarines.
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Why are radio waves useful for communication?
They have a long wavelength allowing diffraction over hills and valleys and reflection from the earth's ionosphere. They can also reach around corners where other types of waves would not be able to.
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What is the range of wavelengths of microwaves?
1mm-1m
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How does a microwave oven work?
They use the microwaves to heat up the water molecules in the food. If the food contains no water molecules a microwave will be far less until some of the ice melts and becomes water.
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How do mobile phones use microwaves?
They use microwaves to communicate with their base stations. They use approximately 1000 times less power than a typical microwave oven, and they emit radiation in all directions, at a different wavelength.
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What other things are microwaves used for?
Satellite communications and Wi-fi.
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How did William Herschel discover infrared light?
He passed white light through a prism, splitting it up into its constituent colours, and measuring the temperature rise of a thermometer as each colour shone on it. He proved their was invisible types of light, undetectable by the human eye.
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How do we feel infrared radiation?
We usually feel it as heat coming from a fire and it is emitted from any hot object.
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What is infrared radiation used in?
Grills, barbecues, thermal imaging cameras, remote controls, short-range military radios and optical fibres.
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Before visible light was discovered, what was it known as?
Light
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How did Isaac Newton demonstrate that white light was made up all other colours of light?
He passed a light beam through a prism of glass showing different colours refracting by different amounts.
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What do we use visible light for?
Photography, illumination of areas we live in, lasers, creating and reading CD's, DVD's and Blu-Ray disks, range-finding in millitary software and surveying.
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How is ultraviolet light different to violet light?
Ultraviolet has a higher frequency (greater than violet)
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Name some uses of UV light?
Causing suntan, fluorescent light bulbs, kill germs in dirty water, blacklights used in nightclubs.
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What happens when UV light is shone on to something UV sensitive?
It is absorbed and re-emitted as visible light
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Other cards in this set

Card 2

Front

What are radio waves used for in communication?

Back

To communicate with submarines.

Card 3

Front

Why are radio waves useful for communication?

Back

Preview of the front of card 3

Card 4

Front

What is the range of wavelengths of microwaves?

Back

Preview of the front of card 4

Card 5

Front

How does a microwave oven work?

Back

Preview of the front of card 5
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