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Electricity Terms
Term | Definition |
---|---|
ammeter | measures electric current (the flow of electrons) - connected in series |
ampere | the unit used to measure current - symbol = A |
voltage | is a measure of the amount of energy supplied by the power source |
voltmeter | measures voltage - connected in parallel |
volts | the unit used to measure voltage - symbol = V |
transformer | changes the voltage supplied to a device - eg 240 V MAINS reduced to 19V for a laptop |
wet cell | 2 different metal electrodes and an electrolyte solution eg car battery - acid and metal electrodes |
electrode | metal conductor |
electrolyte | fluid that conducts electricity |
dry cell | contain a conducting paste |
photovoltaic cells | contain semi-conducting silicon crystals - sunlight knocks electrons off the crystal and they create a current. |
Resistance | R = As electrons pass along a wire they meet resistance to flow |
Resistance factors | type of material, length of wire, diameter |
Conductors | Metals are conductors - the offer very little resistance - copper and aluminium. |
Insulators | offer very high resistance - wood and plastic |
Ohm's Law | V = I R |
Current | I = Capital letter i = amperes |