AQA Electricity Summary

Vocabulary flashcards covering electrical quantities, component characteristics, circuit laws, mains electricity, transformers, and static charge based on the AQA electricity lecture.

Ammeter

An electrical component used to measure electric current that must always be connected in series within a circuit.

Voltmeter

An instrument used to measure the potential difference across a component, always placed in parallel.

Electric current

The rate of flow of electric charge (the flow of electrons in wires in a direct current circuit), represented by the symbol $I$ and measured in amps.

Ohmic conductor

A component whose current is directly proportional to potential difference, yielding a straight-line graph through the origin when kept at a constant temperature.

Filament lamp

A non-Ohmic component whose resistance increases as it gets hotter and emits more light.

Diode

A component that acts like a one-way valve, allowing current to flow in only one direction and keeping current at zero when there is a negative potential difference.

Light dependent resistor (LDR)

A component whose resistance decreases as the light intensity increases.

Thermistor

A thermal resistor whose resistance decreases as its temperature increases.

Series circuit

A circuit arrangement where components are connected one after another, keeping current identical throughout while total potential difference is split between components.

Parallel circuit

A circuit featuring separate loops where current splits at junctions, the potential difference across each loop is identical, and the total resistance is lower than each branch resistor.

Electrical power

The amount of energy transferred per second, measured in watts, and calculated as $P = V \times I$ or $P = I^2 \times R$.

Direct current (DC)

A type of electrical supply where current flows in only one direction around a circuit.

Alternating current (AC)

A type of electrical current whose value alternates between positive and negative, flowing one way and then the other very quickly.

UK mains supply

An alternating current household electricity supply operating at $230\,\text{V}$ with a frequency of $50\,\text{cycles per second}$.

Brown wire

The wire in a three-core cable that provides the alternating potential difference from the supply.

Neutral wire

The wire in a three-core cable that completes the circuit.

Earth wire

A green and yellow safety wire designed to carry electricity back to earth rather than through a person's body if a fault occurs.

National Grid

A system of cables and transformers linking power stations to consumers.

Step-up transformer

A device in the National Grid that increases potential difference and decreases current, thereby reducing energy losses in power transmission.

Step-down transformer

A device in the National Grid used to decrease the voltage.

Static electricity

The buildup of electrical charge caused by the transfer of electrons from one insulator to another through friction or rubbing.

Electric field

A region around a charged object where other charged objects experience an attractive or repulsive force, being strongest near the surface.