Physics-Electricity

Vocabulary flashcards covering key concepts from Topic 2: Electricity (GCSE Physics).

Electric charge

Property of matter with positive and negative signs; like charges repel and opposite charges attract.

Closed circuit

A circuit with no open switches, allowing current to flow continuously.

Potential difference (PD) / Voltage

The driving force that pushes charges around a circuit; measured in volts (V).

Electrical current

The flow of electric charge; measured in amperes (A); in a single closed loop the current is the same everywhere.

Ohm's Law

V = I × R; the current through a component is proportional to the PD and inversely proportional to its resistance.

Resistance

Property that reduces current flow; measured in ohms (Ω).

Ohmic conductor

A component with constant resistance; I is proportional to V and the I–V graph is linear.

Non-ohmic components

Components whose resistance changes with current or other conditions (e.g., lamps, diodes, thermistors, LDRs).

Filament lamp resistance

Resistance increases with temperature as the filament heats up.

Diode

Allows current to flow in one direction; very high resistance in the reverse direction; conducts mainly in one direction.

Thermistor

Resistance changes with temperature; typical thermistors decrease resistance as temperature increases (NTC).

LDR (Light Dependent Resistor)

Resistance decreases with increasing light; high resistance in darkness.

Series circuit

Components connected in a single path; same current through all components; total resistance is the sum of all resistances.

Parallel circuit

Components connected in separate branches; current splits between branches; voltage across each branch is the same; total resistance is less than the smallest branch.

Total resistance in series

R_total = R1 + R2 + …

Potential difference in series

PD from the power supply equals the sum of the PDs across each component.

Current in parallel

Current from the source equals the sum of the currents through each branch; PD is the same across all branches.

National Grid

Network of cables and transformers linking power stations to consumers; transfers electrical energy across the country.

Step-up transformer

Increases the PD from the power station to the National Grid, reducing current and energy loss.

Step-down transformer

Decreases the PD from the grid to consumers for safe, usable voltages.

Live wire

Brown wire, around 230 V; carries the alternating PD; can be dangerous even when switches are off.

Neutral wire

Blue wire, 0 V; completes the circuit.

Earth wire

Green/yellow wire, 0 V; safety conductor that carries current only if there is a fault; prevents the appliance from becoming live.

Insulators

Materials whose electrons remain fixed and do not conduct electricity.

Conductors

Materials whose electrons are delocalised and can flow, conducting electricity.

Static electricity

Charge buildup when two insulators are rubbed together; electrons transfer, creating positive and negative objects.

Sparking

Discharge of static electricity as a spark when enough charge builds up and objects are close but not touching.

Electrostatic force

Force between charged objects; attraction or repulsion; magnitude increases with charge and decreases with distance (inverse-square).

Electric field

Region around a charge where another charge would experience a force; field lines point away from positive charges and toward negative charges; strength increases with charge and proximity.

Charge (Q)

Quantity of electric charge; Q = I × t; measured in coulombs (C).

Energy transferred (E)

Energy transferred by electrical devices; E = P × t and E = Q × V.

Power (P)

Energy transferred per second; P = V × I; power rating indicates how much energy an appliance uses.

Power loss

Heat energy dissipated in resistors; P_loss = I² × R (proportional to resistance and to the square of the current).

Work done in circuits

Energy transferred when charge flows through a circuit; equivalent to the energy delivered to the appliance.