# Electricity

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• Created on: 26-10-19 17:40

Electrical Circuits:

D.C - Direct current: Electrons only flow in one direction around the ciruit
A.C - Alternating Current : Flow of electrons reverse.

Charge (C) = Coulombs. A property of a body which experiences a force in an electric field.

Current (I) = electrical flow of electrons. Current is measured with an ammeter - must be placed in series.

Electrons flow from the negative to positive in a cell, since they are negatively charged particles.

Charge = Current x Time

Current, Potential difference, Resistance:

Potential Difference = voltage of a circuit. Measured with a voltmeter, that is placed in parallel to a component. This measures the difference in energy from one side of the component to the other.

Potential Difference (V) = Energy (J) / Charge (C)

Potential Difference = Current x Resistance

Resistance can be affected by the length of wire, since a longer wire means more resistance.

Fixed Resistor = Directly Proportional graph between Current and Voltage. The resistance is fixed and doesnt change.

Filament Bulb: Not directly proportional. As voltage increases, so does the temperature of the thin wire in the bulb. This causes the ions to vibrate, which makes it more difficult for the electrons to pass through.

Semiconductor Diode - Only allows current to flow in one direction. If vltage arranged to push current the reverse way, no current will flow, since the resistance of the diode is large. When forward biased, the resistance is huge at low potential differences and small at large voltages, which causes a current.

Circuit Rules:

Series:

An electron passes through every component in the circuit. Therefore, if one…