# Electricity

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• Created by: Jessica
• Created on: 27-05-10 14:37

Electrical Circuits.

• Current- Rate of flow of charge.
• Current flows when there is a potential difference. (p.d is a measure of work done, in moving charge around a circuit.)
• Resistance- Opposition to current flow. (measured in ohms.)
• Ohms Law- Current through a resister is directly proportional to pot diff across it, provided temperature remains constant.
• Series- Current stays the same, Pot diff spilts.
• Parallel- Current splits, Pot diff stays the same.
• Ammeter- measures current (put it in series).
• Voltmeter- Measure P.d (put in parallel).

CHARGE (C) = CURRENT(A) x TIME (S)

RESISTANCE (Ohms) = POTENTIAL DIFFERENCE (V) / CURRENT (A)

Mains Electricity.

• UK mains= 230 V, 50HZ.
• Direct current- Batteries/ cells supply current in one direction.
• Alternating Current- Current that constantly changes direction. (the mains supply is alternating.)
• Neutral Terminal- Stays at a P.d close to 0V.
• Live Terminal- ascillates between a possitive and negative potential- current is constantly changing direction.
• Frequency- (Hz) the number of times per second a cycle is completed
• Period- (s) the time taken for a complete cycle.

Plugs

• Brown= Live.
• Blue= Neutral.
• Yellow/ green= Earth.

The wires are made of copper, and have an insulating cover.

• Appliances that have