Physics - Electricity

The flow of elctrical charge.

The greater the rate of flow, the higher the current.

Amperes (A) using an Ammeter.

Coulombs (C)

tells us the electrical potential from one point in a circiut to another.

Amount of electricity travelling in a curcuit.

Volts (V) using a voltmeter.

Q- Charge

I- Current

t- time

R- Resistance

V- Potential Difference

P- Power

A- Set up in series with components

V- Set up parallel to components

It is a measurement of how much current flow is reduced.

Ohms.

Charge = Current x time

Q = I x t

Resistance = Potential Difference      /          R = V

                              Current                                    I

Reduces current.

Increases current.

At a constant temperature, current is directly proportional to the potential difference across the resistor.

As current increases, the resistance increases. The temperature increases as current flows.

Current flows when potential difference flows forward. Very high resistance in reverse.

Distributes electricity in power stations around the UK.

Potential Difference switches direction many times a second, current switches direction (Generator).

Potential Difference remains in one direction, current flows the same direction (Cell or Battery).

Resistance varies with temperature.

Resistance decreases as temperature increases.

Resistance varies with light intensity.

Resistance decreases as light increases.

It is a safety device; Earth wire joins the metal case.

It is a safety device; Earth wire joins the metal case.

Brown

Carries Potential Difference from mains supply.

Potential Difference between live and warth is 230V.

Blue

Completes the circuit.

Potential Difference = OV

Yellow and Green stripes.

Only carries current if there is a fault.

Potential Difference = 0V

50Hz/230V

Increase Voltage; decrease current.

Increases efficiency, reduces heat loss.

Decreases voltage, increase current.

Makes safer for houses.

Watts.

Power = Potential Difference x Current / R = V x I

Power = (current)2 x resistance / P =I2 x R

Energy transferred = Power x time / E = P x t

A circuit with one loop.

Current is all the same in all components.

Total potential difference is shared between all the components.

Total resistance is less then the resistance value of the smallest individual resistor.

A circuit with two or more loops.

Total current is the sum of each component's current.

Potential Difference across all components is the same.

Total resistance is less than the resistance value of the smallest individual resistor.

Cell - Store of chemical energy.

Battery -  Two or more cells in series.

Switch -  Breaks current, turning current off.

Bulb - Lights when current flows.

Ammeter - Measures current.

Voltmeter - Measures Potential Difference.

Diode - Current flows one way.

LED - Emits liught when current flows.

LDR -  Resistance low in bright light.

Fuse - Melts when current is too high.

Resistor - Affects the size of current flowing.

Variable Resistor - Allows current to be varied.

Thermistor - Resistance low at high temperature.