What each part of the spectrum is used for and why its properties suit that job, plus the dangers of ultraviolet, X-rays and gamma rays.
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1.Give two uses of radio waves.
Television and radio broadcasting, and other long distance communication.
2.Why are radio waves suited to broadcasting?
They have long wavelengths, can travel long distances, and are not absorbed much by the atmosphere.
3.Give two uses of microwaves.
Satellite communications and cooking food.
4.Why are microwaves used for satellite communication?
They can pass through the atmosphere without being absorbed, so they reach satellites in orbit.
5.How do microwaves cook food?
They are absorbed by water molecules in the food, which increases the internal energy and heats it throughout.
6.Give three uses of infrared.
Electrical heaters, cooking food, and infrared cameras.
7.How does an infrared camera work?
It detects the infrared radiation emitted by objects, and warmer objects emit more, so a temperature image is produced.
8.Give two uses of visible light.
Fibre optic communications and photography.
9.Why is visible light used in optical fibres?
It can be reflected along the fibre with very little absorption, carrying large amounts of data quickly.
10.Give two uses of ultraviolet.
Energy efficient lamps, sun tanning beds, and detecting forged banknotes.
11.Give a use of X-rays.
Medical imaging of bones, and security scanning.
12.Why do X-rays show bones clearly?
They pass through soft tissue but are absorbed by denser bone, producing a shadow image.
13.Give two uses of gamma rays.
Sterilising medical equipment, and treating cancer with radiotherapy.
14.What are the hazards of ultraviolet?
It can cause skin to age prematurely and increases the risk of skin cancer, and it can damage the eyes.
15.What are the hazards of X-rays and gamma rays?
They are ionising, so they can cause mutations in cells that may lead to cancer.
16.How is radiation dose measured?
In sieverts, or millisieverts.
17.How many millisieverts are in a sievert?
1000.
18.What does radiation dose represent?
The risk of harm from exposure, taking into account both the amount and the type of radiation.
19.How do radiographers protect themselves?
By standing behind a lead screen or leaving the room, and by limiting the time and number of exposures.
20.Why is protective clothing used with X-rays?
Lead absorbs X-rays, so it shields parts of the body that do not need to be imaged.
21.Why must the benefit of a medical scan be weighed against the risk?
The radiation itself carries a small risk of causing harm, so it is only justified when the diagnostic benefit is greater.
22.Why can microwaves be dangerous?
They are absorbed by water in body tissue, which can heat and damage internal organs.
23.Which is more dangerous, ultraviolet or infrared, and why?
Ultraviolet, because it has a higher frequency and is ionising, whereas infrared mainly causes heating.
24.Why does higher frequency mean more danger?
Higher frequency waves carry more energy, and enough energy allows them to ionise atoms and damage DNA.
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