Microwave & infrared (Edexcel GCSE Physics Combined Science): Flashcards
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Why are microwaves used for satellite communication?
Why are microwaves used for satellite communication?
Pass through Earth's atmosphere
Why different wavelengths for communication vs oven microwaves?
Why different wavelengths for communication vs oven microwaves?
Communication ones travel long distances without absorption
How microwave ovens cook food
How microwave ovens cook food
Heat water molecules inside food
Microwave penetration depth in food
Microwave penetration depth in food
A few centimetres
What absorbs microwaves in food
What absorbs microwaves in food
Water molecules
Relationship: IR emission & object temperature
Relationship: IR emission & object temperature
Hotter objects emit more IR
What infrared cameras produce
What infrared cameras produce
Thermal images
IR camera police use
IR camera police use
Detect suspects in dark
IR use in cooking example
IR use in cooking example
Toasters (IR heats food when absorbed)
What electric heaters emit
What electric heaters emit
IR radiation & visible light
IR communication distance feature
IR communication distance feature
Short distances only
IR communication receiver requirement
IR communication receiver requirement
Must be in line of sight of emitter
What are optical fibres
What are optical fibres
Thin glass/plastic strands carrying data
How data travels in optical fibres
How data travels in optical fibres
Total internal reflection of IR pulses
Why single wavelength in optical fibres
Why single wavelength in optical fibres
To prevent dispersion (information loss)