Physics - Unit 2 - electricity (copy)

Closed loop that contains a cell and something for electrons to flow through, such as a wire

Two or more cells

Force draining the flow of electrons, provided by the cell or battery, measured in volts

A measure of the flow of electrons around the circuit, measured in amps

Everything that resists the flow of electrons, measured in ohms

Longer line on the battery / cell is the positive, so the current flows out of it. Shorter line on the battery / cell is the negative, so the current flows into it. Current always flows from the negative to the positive

Potential difference = current x resistance

Heats up so increases resistance

Only allows current to flow in one direction as it has a really high resistance in the reverse direction, so no current can flow

A measure of the total current that flowed within a certain period of time, measured in coulombs

Charge = current x time

A switch used to turn a circuit on and off

An electrical current heats the filament in a bulb so that it gives out light

A resistor restricts or limits the flow of electrical current. A fixed resistorhas a resistance that does not change

Moving the position of the slider on this resistor, changes the resistance. A variable resistor is used in some dimmer switches and volume controls.

The resistance of a thermistor depends on its temperature. At low temperatures, the thermistor has a high resistance. As the temperature increases, the resistance decreases.

The resistance of a LDR depends on light intensity. At low light levels, the LDR has a high resistance. As the light intensity increases, the resistance decreases.

A semiconductordiode allows current to flow in one direction only. Current will not flow in the other direction.

Measured using an ammeter

Measured using a voltmeter

Potential difference = energy / charge

A series circuit is one loop; all electrons in that loop form one current. An ammeter will measure the same current wherever it is placed in the circuit. The potential difference supplied is equal to the total of the potential differences across all other components.

In parallel circuits, electrical components are connected alongside one another, forming extra loops. The current is not shared equally across the loops.

power = current × potential difference

power = current² × resistance

Also called dc. An electric current that flows in one direction only.

Also called ac. An electric current that regularly changes its direction and size.

Yellow and green. Copper wire coated in striped plastic that provides a path for current to flow from the case of the device to the ground if there is a fault

Blue. Copper wire coated with blue plastic that also connects to the cable in the wall and completes the circuit

Brown. Copper wire coated with brown plastic along which the current enters the device.

All three wires in the cable are bundled together and there is extra plastic insulation wrapped round them all for safety

This holds the cable tightly in place so that wires do not become loose

A glass or ceramic canister containing a thin wire that melts if the current gets too high to break the circuit.

Energy = power x time

power = potential difference × current

230V

A transformer that increases the voltage and decreases the current of the ac supply.

A transformer that decreases the voltage and increases the current of the ac supply.

Electric charge that accumulates on an insulated object, for example because of friction.

Electrons, which are negatively charged, may be ‘rubbed off’ one material and on to the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with a positive charge.

An electric field is a region where charges experience a force