Circuits, EMF, Potential Difference, Resistors, Electrical Hazards and Safety

Flashcards on Series and Parallel Circuits, EMF, Potential Difference, Resistors, Potential Dividers, Electrical Hazards and Safety

Series Circuit

A circuit with only one complete loop.

Parallel Circuit

A circuit with multiple loops (branches).

Current in Series Circuits

The same at every point in the circuit.

Current in Parallel Circuits

Splits at junctions, with the current before a junction equaling the sum of currents in all branches after the junction.

EMF in Series Circuits

When cells are connected in series, the total EMF is the sum of individual EMFs.

Potential Difference in Series Circuits

The sum of potential differences (voltages) across components equals the total EMF of the power source.

Potential Difference in Parallel Circuits

Potential difference (voltage) across each branch equals EMF of the power source.

Resistors in Series

The total resistance is the sum of individual resistances: R total = R1+R2+R3+R4

Resistors in Parallel

Total resistance is less than the smallest resistor in the circuit. 1/R = 1/R1 + 1/R2 + ….

Potential Divider

A circuit that splits the total potential difference (voltage) of a power source between two resistors in series.

Damaged Insulation

An electrical hazard that can be protected against with insulation or double insulation.

Overheating

A common electrical hazard, protection against which is best achieved with fuses and trip switches.

Live Wire

The brown wire in mains plugs that carries current from mains and is the most dangerous.

Neutral Wire

The blue wire in mains plugs that completes the circuit (return path).

Earth Wire

The green and yellow wire in mains plugs that provides a safety measure to prevent metal casing becoming live.

Double Insulation

An electrical safety feature with no metal case, two layers of insulation, and no earth wire needed.

Earthing

When a metal case exists if a live wire touches the case, the earth wire provides a low resistance path to ground.

Fuses

A thin metal wire inside a plug that melts if current is too high, breaking the circuit.

Trip Switches

Found in the consumer unit, these trip off automatically if current exceeds a safe level, cutting the circuit.