GCSE Physics Overview: Energy, Electricity, and Atomic Structure

Vocabulary and key concepts from a physics lecture covering units, energy stores, electricity, atomic structure, and nuclear physics.

Standard Form (Micro-)

$5 \times 10^{-6}$ represents five micrometers converted to meters, indicating division by ten six times.

Conservation of Energy

The principle that total energy in any interaction is always conserved; it cannot be created or destroyed, though it can turn into matter in nuclear reactions.

Kinetic Energy

Energy calculated using the formula $\frac{1}{2}mv^2$, where $m$ is mass in kilograms and $v$ is speed or velocity.

Gravitational Potential Energy (GPE)

Energy calculated by $mgh$, where $m$ is mass, $g$ is gravitational field strength ($9.8\,N/kg$ or $10\,N/kg$), and $h$ is the change in height in meters.

Elastic Potential Energy

Energy stored in a spring, calculated as $\frac{1}{2}ke^2$, where $k$ is the spring constant and $e$ is the extension.

Specific Heat Capacity (SHC)

The amount of energy needed to raise the temperature of $1\,kg$ of a substance by $1^\circ C$, used in the equation $E = mc\Delta T$.

Closed System

A system where no energy is lost to or enters from the surroundings, allowing energy to be equated between stores (e.g., $GPE = KE$).

Work

Another term for the amount of energy used, often referred to in the context of overcoming friction or air resistance.

Power

The rate of energy transfer, calculated as energy divided by time ($P = \frac{E}{t}$) and measured in Watts ($W$) or Joules per second ($J/s$).

Efficiency

A measure of how much energy or power is used usefully, calculated by dividing useful energy output by total energy input.

Finite / Non-renewable Sources

Energy sources that once used up cannot be replaced, such as fossil fuels (coal, oil, gas) and nuclear fuel.

Potential Difference (Voltage)

A measure of how much energy is transferred per Coulomb of charge, calculated as $V = \frac{E}{Q}$ and measured in Volts ($V$).

Current

The rate of flow of charge, measured in Amps ($A$) and defined by the formula $I = \frac{Q}{t}$.

Resistance

The property of a component to oppose the flow of charge, measured in Ohms ($\Omega$) and related by $V = IR$ (Ohm's Law).

Ohmic Conductor

A resistor with a constant resistance, resulting in a current-voltage graph that is a straight line through the origin.

Filament Lamp

A component whose resistance increases as the temperature of its metal filament rises with higher current, producing a curved current-voltage graph.

Diode

A component that allows current to flow in only one direction, having very high resistance in the opposite direction.

Thermistor

A temperature-sensitive resistor whose resistance decreases as its temperature increases.

LDR (Light Dependent Resistor)

A component whose resistance decreases as light intensity increases, used in light-sensing circuits.

Alternating Current (AC)

Current that constantly changes direction, resulting from an alternating potential difference; UK mains electricity is $230\,V$ at $50\,Hz$.

Step-up Transformer

A device that increases voltage and decreases current outside power stations to reduce energy lost as heat in transmission cables.

Density

A measure of mass per unit volume, calculated as $\rho = \frac{m}{V}$ and measured in $kg/m^3$.

Internal Energy

The sum of the kinetic energy and potential energy of all the particles in a substance.

Specific Latent Heat

The energy required to change the state of $1\,kg$ of a substance without changing its temperature, calculated as $E = mL$.

JJ Thomson

The scientist who discovered electrons and proposed the Plum Pudding model of the atom.

Ernest Rutherford

The scientist who discovered the small, dense, positive nucleus of the atom.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Alpha Radiation

A highly ionizing but lowly penetrating particle consisting of two protons and two neutrons (a helium nucleus).

Beta Radiation

A fast-moving electron emitted when a neutron in the nucleus decays into a proton.

Gamma Radiation

High-energy electromagnetic waves with low ionizing power but high penetrating ability, often reduced by lead or concrete.

Half-life

The time required for the activity or the number of unstable nuclei in a radioactive sample to decrease by half.

Nuclear Fission

The process of splitting a large nucleus into two smaller daughter nuclei, releasing energy and neutrons in a chain reaction.

Nuclear Fusion

The process where two light nuclei (like hydrogen) fuse to form a heavier nucleus (like helium), releasing vast amounts of energy in stars.