Physics 3 - Electricity

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  • Created by: Ls
  • Created on: 17-05-14 23:05
parts of a plug (8)
earth wire, live wire, neutral wire, case, pin, fuse, cable grip and outer insulation
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case
made from plastic/rubber because they are good electrical insulators
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pin (2)
brass (good conductor) compromise from expensive copper, earth pin is the longest
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wires (2)
made of copper (good conductor) coated with flexible plastic (good insulator, flexible)
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live wire (2)
dangerous (contains main's voltage 230 volts), alternates between +VE and -VE voltage
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neutral wire (4)
completes circuit, earthed back at power station, not as high as the live wire, always OV
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wiring plugs (4)
right colored wire, firmly screwed, no bare wires, cable grip tightly fastened over cable outer layer
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earth wire
safety feature for appliances with metal casing
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use for earth wire
If live wire touches appliance without earth wire, person gets an electric shock. If there is the same fault: live wire > metal casing > earth wire > earth, large current flows, fuse melts and cuts off the current
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double insulation
appliance with plastic casing, which doesn't need earthing
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fuses
melt at a certain current to break and stop the circuit and stop it heating up and damaging the appliance or starting a fire
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finding current
current (A) = power (W) / voltage (V)
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finding power
power (W) = energy (J) / time (s)
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choosing fuses
1A, 3A, 10A, 13A; choose the smallest fuse above the current
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electrical hazards (7)
long/frayed cables; cables in contact with something hot/wet; pets or children; water near sockets/shoving things into sockets; damaged plugs/too many in one socket; lighting sockets without bulbs; appliances without covers on
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circuit breakers
switches flip open and break circuit when current is too high; close switch to reset
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thermal
brass on bi-metallic strip heats up and bends upward; brass flips down (circuit breaks because of gap); bring brass up to reconnect the circuit
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magnetic (MCB)
electromagnet gets very strong, attracts iron bar, turns anti-clockwise, spring flips down, contacts come apart
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current
rate of flow of charge
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resistor
gets hot if electrical charge flows through, varies the current in a circuit
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DC
direct current: always flow in the same direction (battery or cell)
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AC
alternating current: repeatedly changes (mains) - UK frequency of 50 cycles/second (hertz)
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Other cards in this set

Card 2

Front

made from plastic/rubber because they are good electrical insulators

Back

case

Card 3

Front

brass (good conductor) compromise from expensive copper, earth pin is the longest

Back

Preview of the back of card 3

Card 4

Front

made of copper (good conductor) coated with flexible plastic (good insulator, flexible)

Back

Preview of the back of card 4

Card 5

Front

dangerous (contains main's voltage 230 volts), alternates between +VE and -VE voltage

Back

Preview of the back of card 5
View more cards

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