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PHYSICS UNIT 6 - LIGHT & THE ELECTROMAGNETIC SPECTRUM (Applications of…
PHYSICS UNIT 6 - LIGHT & THE ELECTROMAGNETIC SPECTRUM 
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Applications of EM Waves
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Visible light to transmit data - fibre optic cable- data over long distances using pulses of visible light.
Microwaves -satellites & microwave ovens (different wavelengths for each), phones & wifi hubs.
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Gamma radiation - high energy - medicine eg. gamma-emitting source injected into patient & progress followed around body.
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Hazardous Effects
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Ultra violet - damages surface cells which can lead to sunburn or blindness and increased risk of cancer. Skin darkens to halt mutation of cells e.g.. suntan.
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X-rays & Gamma rays - ionising radiation - carry enough energy to knock electrons off atoms - can cause gene mutation or cell destruction and cancer.
When EM radiation enters living tissues often harmless but sometimes creates havoc. Effects of each type of radiation is based on how much energy the wave transfers.
Substances
Substances may absorb, transmit, refract or reflect EM waves in ways that vary with wavelength
All objects continually emitting & absorbing infrared radiation e.g.. hot cup of tea emits more IR radiation than it absorbs as it cools down. Cold glass of water on sunny day absorbs more IR than it emits as it warms up.
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