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Electricity (Electrical quantities (Power (P) (Watts) - Rate per unit time…
Electricity
Electrical quantities
Power (P) (Watts) - Rate per unit time, at when electrical energy is transferred by an electrical circuit.
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Charge (Q) (Coulombs) - Measure of the number of electrons passing through the circuit at a given point.
Electrical safety
Fuse - A cylinder containing a thin piece of wire. As the metal in a wire tends to have a low melting point, too large a current will melt the fuse wire, causing the circuit to shut off. They come in a variety of sizes, 3A, 5A, 13A.
Circuit breaker - A switch that opens and breaks the circuit when too large a current flows. These do not need to be replaced, only reset.
Double insulation - As most appliances use a casing made from insulators instead of metal (plastic), double insulated appliances ensure the user cannot be shocked by the electrical parts.
Earth wire - Appliances with a metal casing are attached to an earth wire. If the live wire breaks and comes into contact with the metal, the earth wire provides a low resistance path for the current to follow.
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Resistance
Ohms law
The current flowing through a a resistor at a constant temperature is directly proportional to the potential difference across it. The higher the potential difference, there is more of an increase in the current.
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