AQA GCSE Physics Topic 2: Electricity Flashcards

Vocabulary practice flashcards covering AQA GCSE Physics Topic 2: Electricity notes, including circuits, resistors, mains supply, power formulas, the National Grid, static electricity, and electric fields.

Circuit Symbols

Standardised visual representations used in schematic diagrams to depict electrical components such as switches, cells, batteries, diodes, resistors, lamps, fuses, voltmeters, ammeters, thermistors, and LDRs.

Electrical Charge

A fundamental property of matter where positive and negative charges exist. For charge to flow in a circuit, the circuit must be closed with no open switches and contain a source of potential difference.

Electrical Current

The rate of flow of electrical charge in a circuit. In a single closed loop, current has the exact same value at any point.

Charge Flow Equation

$Q = I \times t$, where $Q$ is charge flow in coulombs ($\text{C}$), $I$ is current in amperes ($\text{A}$), and $t$ is time in seconds ($\text{s}$).

Ohm's Law Equation

$V = I \times R$, where $V$ is potential difference in volts ($\text{V}$), $I$ is current in amperes ($\text{A}$), and $R$ is resistance in ohms ($\text{Ω}$).

Ohmic Conductor

A conductor with constant resistance, where the current passing through it is directly proportional to the potential difference across it, producing a linear $I\text{-}V$ graph.

Filament Lamp Resistance

A non-linear component whose resistance increases as its temperature increases, because flowing electrons collide more frequently with vibrating metal atoms inside the filament.

Thermistor

A temperature-dependent component whose resistance decreases as temperature increases, commonly used in thermostats and temperature detectors.

LDR (Light Dependent Resistor)

A light-dependent resistor whose resistance decreases as light intensity increases (reaching maximum resistance in the dark), commonly used in automatic night lights.

Diode

A component that allows electric current to flow freely in one direction while offering very high resistance in the reverse direction to block current.

I-V Characteristic Graphs

Plots of current against potential difference for circuit components; the gradient equal to $\frac{1}{\text{resistance}}$, meaning a steeper gradient indicates a lower resistance.

Series Circuit

A closed circuit where components are connected end-to-end in a single path. Current is equal at all points, potential difference is shared across components, and total resistance equals $R_{\text{total}} = R_1 + R_2 + \dots$

Parallel Circuit

A branched circuit where current splits across multiple paths. Potential difference is identical across each branch, and total resistance is less than the resistance of the smallest individual branch resistor.

Mains Electricity (UK)

An alternating current (AC) domestic electricity supply with a frequency of $50\,\text{Hz}$ and a voltage of approximately $230\,\text{V}$.

Alternating Current (AC)

An electric current that continuously varies in direction, alternating between positive and negative values, supplied by mains electricity.

Direct Current (DC)

An electric current consisting of charge moving in one fixed direction only, supplied by cells and batteries.

Live Wire

The brown wire in a plug operating at $230\,\text{V}$ that carries alternating potential difference from the supply.

Neutral Wire

The blue wire in a plug operating at $0\,\text{V}$ that completes the electrical circuit.

Earth Wire

The green-and-yellow striped safety wire operating at $0\,\text{V}$ that carries current only during a fault to prevent appliance casings from becoming live.

Electrical Power Equations

Formulas calculating power transferred per second: $P = I \times V$ and $P = I^2 \times R$, where $P$ is power in watts ($\text{W}$).

Energy Transferred Equations

Formulas calculating electrical energy transferred: $E = P \times t$ and $E = Q \times V$, where $E$ is energy in joules ($\text{J}$).

National Grid

A nationwide system of high-voltage cables and transformers connecting power stations to domestic and industrial consumers across the UK.

Step-up Transformer

A transformer that increases potential difference and decreases current between power stations and the National Grid to reduce energy loss as heat.

Step-down Transformer

A transformer that decreases potential difference from the National Grid to lower, safe levels for domestic consumer use.

Conductors vs Insulators

Conductors allow delocalised electrons to flow freely through the material, whereas insulators keep electrons fixed in place so they cannot conduct electricity.

Static Electricity

The build-up of electric charge produced when two insulating materials are rubbed together, transferring electrons from one object to the other.

Sparking

The discharge that occurs when enough static charge accumulates on an object, causing electrons to jump through the air to another object to balance the charges.

Electric Field

A region surrounding an electric charge where a non-contact electrostatic force is exerted on other charges; field lines point away from positive charges and towards negative charges at right angles.