P12 - Electromagnetic Waves.
P12 - Electromagnetic waves.
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P12. 1 - Electromagnetic spectrum.
Gamma - heighest frequency.
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- Human eye can only detect visible light which has a wavelength of 350nm to 650nm.
- Electromagnetic waves tranfer energy from source - absorber.
- wavespeed = frequency x wavelength.
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P12.2 - Light, infared, microwaves and radiowaves.
- white light - all colours of spectrum
- Infared - carrying signals from remote controls and optical fibres.
- Microwaves - satellite tv programmes and phone calls.
- Radiowaves - radio and TV broadcasting and phone calls.
- Mobile phone radiation is microwave radiation and radiowaves .
- different types of elctromagnetism are dangerous.
- Microwaves and radiowaves heat internal body parts.
- Infared - skin burns
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P12.3 - Communications.
- wavelength affects; how far they travel, how much they spread and how much info they carry.
- Futher reaserch needed - are phones safe to use?
- Carrier waves used to carry info. They do this by varying amplitude.
- Optical vibres - thin, transparent. Used to transmit communication signals by light and infared radiation.
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P12.4 - Ultraviolet,X-rays and gamma rays.
- Ultraviolet - shorter wavelength than visible light and can harm skin and eyes.
- X-RAYS - hospitals to make X-ray Images.
- Gamma rays kill bateria in food, sterilise equipment and kill cancer cells.
- Ionising radiation - uncharged atoms become charged.
- X-rays and GAMMA damage living tissues.
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12.5 - X-rays in medicine.
- used in hospitals to;
- make images of internal body parts
- destry tumours near body surface.
- They are ionising rdiation so can damage living tissue .
- Absorbed by bones and teeth more than soft tissue.
- People who work in X-ray areas must wear protective lead.
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