GCSE Physics - Electrical Circuits

A set of vocabulary flashcards covering components, circuit rules, power equations, and I-V characteristics for GCSE Physics Electrical Circuits.

Power (in a circuit)

The energy transferred per second, measured in Watts where $1\,\text{W} = 1\,\text{Joule per second}$.

Thermistor

A component whose resistance changes depending on temperature, where higher temperature = lower resistance.

LDR (Light Dependent Resistor)

A component whose resistance changes depending on the light on it, where brighter light = lower resistance.

Variable resistor

A component whose resistance can be changed by moving a slider or turning a dial, e.g., a dimmer switch.

Ammeter

A device used to measure current that must be connected in series.

Voltmeter

A device used to measure voltage that must be connected in parallel.

Current in a Series Circuit

Equal everywhere in the circuit.

Voltage in a Series Circuit

Shared between the components, but must add to the voltage from the power source.

Resistance in a Series Circuit

Increases when adding resistors in series, according to the equation $R = R_1 + R_2$.

Current in a Parallel Circuit

Shared between the components, but must add to the current from the power source.

Voltage in a Parallel Circuit

Equal across each component.

Resistance in a Parallel Circuit

Decreases when adding resistors in parallel, according to the equation $\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2}$.

Current Calculation Equation

$$\text{Current}\,(\text{A}) = \frac{\text{Voltage}\,(\text{V})}{\text{Resistance}\,(\Omega)}$$

Power Equation (Voltage & Current)

$$\text{Power}\,(\text{W}) = \text{Voltage}\,(\text{V}) \times \text{Current}\,(\text{A})$$

Power Equation (Current & Resistance)

$$\text{Power}\,(\text{W}) = (\text{Current}\,(\text{A}))^2 \times \text{Resistance}\,(\Omega)$$

Energy Equation

$$\text{Energy}\,(\text{J}) = \text{Power}\,(\text{W}) \times \text{Time}\,(\text{s})$$

Resistor or wire I-V curve (At a constant temperature)

Displays constant resistance.

Filament lamp I-V curve

Displays resistance that increases at higher voltages.

Diode I-V curve

Displays very high resistance (no current) until a specific voltage is reached.