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Forces and Motion, Electricity, Waves - Coggle Diagram
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Electricity
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Current
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conventional current = rate of flow of positive charge in opposite direction to flow of electrons which are negatively charged
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dangers of electricity
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earthing metal cases
earth wires create a safe route for current to flow through in case of a short circuit, preventing electric shocks
have very low resistance so a strong current surges through them which blows the fuse disconnecting appliance
double insulation
either have plastic casing which doesn't conduct the electricity or have an earth wire that is not in contact with the metal casing to prevent electric shocks
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Waves
EM spectrum
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x-rays
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ionising radiation, can cause mutations in DNA leading to cancer if exposed to too much
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using waves
reflection
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frequency, wavelength and speed all are unchanged
refraction
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when a wave enters a more dense medium, speed decreases and bends toward normal
when a wave enters a less dense medium, speed increases and bends away from normal
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optical fibres
long thin rod of glass surrounded by cladding which uses total internal reflection to transfer information by light
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doppler effect
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The wave front is moving at a frequency and the wave speed is constant. As the source moves towards the observer, there will be compressions of the wave front which causes the frequency to increase for the observer.
When the source moves away from the observer, the wave front spread apart and the frequency decreases for the observer