GCSE Physics - Electrical Circuits

Vocabulary flashcards covering key concepts, equations, and circuit components from the GCSE Physics Electrical Circuits unit.

Power (in an Electrical Circuit)

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

Watt ($\text{W}$)

The unit of measurement for power, equivalent to $1\,\text{Joule per second}$.

Power Equation (using Voltage and Current)

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

Power Equation (using Current and Resistance)

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

Electrical Energy Equation

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

Current in a Series Circuit

The current is equal everywhere in all parts of the circuit.

Voltage in a Series Circuit

Voltage is shared between the components, and individual voltages add up to equal the voltage from the power source.

Current in a Parallel Circuit

Current is shared between the current loops and must add up to equal the total current from the power source.

Voltage in a Parallel Circuit

The voltage is equal across each individual component.

Ammeter

An instrument used to measure electrical current, which must always be connected in series.

Voltmeter

An instrument used to measure electrical voltage, which must always be connected in parallel across a component.

Resistance Equation

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

Total Resistance in Series

Adding resistors in series increases total resistance; total resistance is calculated as $R = R_1 + R_2$.

Total Resistance in Parallel

Adding resistors in parallel decreases total resistance so that total resistance is lower than the lowest individual resistor value, calculated as $\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2}$.

Fixed Resistor

A resistor that maintains a constant value of electrical resistance.

Variable Resistor

A resistor that can be adjusted to alter the amount of resistance and change the current in a circuit.

Filament Lamp (Resistance Behavior)

Current passing through the bulb causes heating; as temperature increases, the resistance of the lamp increases.

Light Dependent Resistor (LDR)

A component whose resistance decreases as light intensity increases.

Thermistor

A component whose resistance decreases as temperature increases.

Diode

A circuit component that allows electric current to flow in one direction only.

I-V Characteristic of a Resistor at Constant Temperature

Current is directly proportional to voltage, producing a straight-line graph through the origin.

I-V Characteristic of a Filament Lamp

As voltage increases, current and temperature increase, causing resistance to increase and the current-voltage curve to level off at higher voltages.

I-V Characteristic of a Diode

Current flows only when voltage is applied in the forward direction; in the reverse direction, resistance is extremely high and no current flows.