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ELECTRICITY - Coggle Diagram
ELECTRICITY
Electrical safety
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Earthing is used to protect you from an electric shock. It does this by providing a path for a fault current to flow to earth. It also causes the protective device to switch off the electric current to the circuit that has the fault.
Double insulation protects the user of the appliance from an electrical shock by preventing any possibility of the external casing becoming live
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Current and resistance
Current is conserved at a junction in a circuit because charge is always conserved. Current is measured with an ammeter connected in series with the component
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THERMISTOR - As temperature increases, resistance decreases
LDR - As illumination increases, resistance decreases
Why does a current in a resistor results in the electrical transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts
Electricity, in metals, is caused by a flow of electrons.
As the electrons pass through the metal they collide with ions: The ions resist the flow of the electrons.
As electrons flow through the metal, they collide with ions, making them vibrate more
When the electrons collide they lose some energy, giving it to the ions, which start to vibrate more.
As a result of this, the metal heats up.
This effect is used in many electric heaters, including electric ovens, some types of electric hob, toasters, kettles and old fashioned incandescent light bulbs.
Current in wires, resistors, bulbs and diodes
In a bulb, resistance increases because it gets hot and temperature also increases. Current level off
In a diode there is no current in negative direction, but there is current in positive direction after 0.6V. A diode only allows current to pass in one direction
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Key Things to know
Mains electricity
Know the difference between mains electricity being alternating current (a.c) and direct current (d.c) being supplied by a cell or battery
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