GCSE Physics Study Guides

Electric circuits transfer energy via the flow of charge (current) driven by a potential difference (voltage) and opposed by resistance. Applying Ohm's Law (V = IR), series and parallel circuit rules, I-V characteristics of components, and electrical power equations (P = VI and P = I²R) underpins GCSE Physics Paper 1.

Waves transfer energy and information from one place to another without transferring matter. In GCSE Physics, you compare transverse and longitudinal waves, apply the wave equation (v = fλ), investigate reflection and refraction, and learn the properties, uses, and hazards of the electromagnetic spectrum.

Energy is stored in different ways and transferred between stores by heating, waves, electric current, or mechanical work. The principle of conservation of energy states that energy cannot be created or destroyed, allowing you to equate kinetic, gravitational potential, elastic, and thermal energy transfers and calculate device efficiency.

A force is a push or pull that acts on an object due to its interaction with another object, capable of changing its speed, direction, or shape. This guide covers scalar vs vector quantities, resultant forces, Newton's three laws of motion, terminal velocity, stopping distances, and conservation of momentum.

Unstable atomic nuclei undergo random radioactive decay by emitting alpha particles, beta particles, or gamma rays to become more stable. This guide covers the plum pudding vs nuclear models of the atom, the penetrating power and ionising ability of alpha, beta, and gamma radiation, nuclear decay equations, and half-life calculations.

Magnetic fields surround permanent magnets and electric currents. When a current-carrying conductor is placed inside an external magnetic field, the two magnetic fields interact to produce a force on the wire (the motor effect, F = BIL), which drives electric motors and loudspeakers.

Space physics examines the formation and life cycle of stars, the mechanics of planetary and satellite orbits, and cosmological evidence for the origin of the universe. Observations of galactic red-shift and cosmic microwave background radiation support the Big Bang model of an expanding universe.

The kinetic particle model explains the properties of solids, liquids, and gases in terms of the arrangement, motion, and potential energy of their particles. Heating a substance increases its internal energy, either raising its temperature (governed by specific heat capacity) or changing its state at constant temperature (governed by specific latent heat).

When a substance is heated, the thermal energy transferred either increases the average kinetic energy of its particles (raising its temperature according to Specific Heat Capacity, ΔE = mcΔθ) or increases the potential energy of its particles by overcoming intermolecular forces during a change of state (at constant temperature according to Specific Latent Heat, E = mL). Materials with a high specific heat capacity, such as water (4,200 J/kg°C), store large amounts of thermal energy per kilogram for every degree of temperature rise. Examiners frequently test multi-step calculations combining electrical power (E = Pt) with ΔE = mcΔθ, heating curve plateaus, and the metal block Specific Heat Capacity required practical.

Energy resources used for electricity generation, transport, and heating are classified as either non-renewable (fossil fuels and nuclear fuel, which are finite and will eventually run out) or renewable (energy resources that are replenished as they are used and will never run out). While fossil fuels and nuclear power provide reliable baseload electricity that can meet predictable national demand, fossil fuels emit greenhouse gases (CO₂) and acid rain pollutants (SO₂), whereas nuclear power generates hazardous radioactive waste. Examiners frequently set 6-mark evaluation questions comparing energy resources across four criteria: reliability, environmental impact, start-up response time, and capital vs running costs.

In the UK, domestic mains electricity is an alternating current (AC) supply with a potential difference of about 230 V and a frequency of 50 Hz, delivered to appliances via three-core cables containing live, neutral, and earth wires. Appliances transfer electrical energy at a rate governed by the power equations P = VI and P = I²R, while fuses and earth wires protect users from electrocution and electrical fires. On a national scale, the National Grid uses step-up transformers to transmit electricity at ~400,000 V (reducing current so wasted heating power P = I²R in overhead cables is minimised) before step-down transformers reduce the potential difference to a safe 230 V for homes.

In Triple Science GCSE Physics, static electricity occurs when two electrical insulators are rubbed together, causing negatively charged electrons to be transferred by friction from one material's surface to the other. The material that gains electrons becomes negatively charged, and the material that loses electrons is left with an equal positive charge (protons in the nucleus never move). Every charged object creates an electric field in the space around it, where another charged object experiences a non-contact electrostatic force of attraction or repulsion, and where a high enough potential difference can ionise air molecules to cause a spark.

The particle model of matter explains why solids, liquids, and gases have vastly different densities (ρ = m / V) and compressibilities based on the spacing, arrangement, and kinetic energy of their particles. In gases, rapidly moving particles collide randomly with the walls of their container; each collision exerts a force at right angles to the wall, creating an outward gas pressure (p = F / A). Examiners regularly test the 6-mark required practical for measuring the density of regular solids, irregular solids (using a displacement Eureka can), and liquids, as well as explaining how heating or compressing a gas increases its pressure (including Boyle's Law, pV = constant, for Triple Science).

Unstable atomic nuclei decay at random into more stable nuclei by emitting alpha (α), beta (β), or gamma (γ) ionising radiation; although individual decays cannot be predicted, the time taken for half of a large number of radioactive nuclei to decay (the half-life) is constant for any given isotope. Safely handling radioactive sources requires distinguishing between irradiation (exposing an object to radiation from an external source) and contamination (the unwanted presence of radioactive atoms on or inside an object). In Triple Science GCSE Physics, nuclear energy is explored through controlled nuclear fission chain reactions in reactors and nuclear fusion inside stars.

Motion in a straight line is analysed using vector quantities (displacement, velocity, and acceleration) that have both magnitude and direction, alongside scalar quantities (distance and speed) that have magnitude only. On a distance-time graph, the gradient represents speed, whereas on a velocity-time graph, the gradient represents acceleration (a = Δv / t) and the area enclosed under the graph represents the total distance travelled (displacement). Examiners frequently test multi-stage velocity-time graph area calculations, the uniform acceleration equation v² - u² = 2as, and the 6-mark explanation of terminal velocity using Newton's First and Second Laws.

The total stopping distance of a vehicle is the sum of the thinking distance (the distance travelled during the driver's reaction time) and the braking distance (the distance travelled under the braking force). When brakes are applied, work done by friction between the brake pads and discs transfers kinetic energy into thermal energy (½mv² = Fd), which explains why doubling a car's speed quadruples its braking distance. For Higher Tier students, examiners also test the conservation of momentum (p = mv) in collisions and explosions, and how safety features (crumple zones, seatbelts, and airbags) increase impact time to reduce the impact force via F = mΔv / Δt.

To stretch, bend, or compress an object, more than one force must be applied to it (otherwise a single force would simply accelerate the entire object). Hooke's Law states that the extension of an elastic object, such as a steel spring, is directly proportional to the force applied to it (F = ke), provided the limit of proportionality is not exceeded. Examiners regularly test the Hooke's Law required practical, calculating the spring constant (k) from the gradient of a force-extension graph, and equating work done to elastic potential energy stored in a stretched or compressed spring (E_e = ½ke²).

In Triple Science GCSE Physics, a force or system of forces can cause an object to rotate about a pivot; the turning effect of a force is called the moment of the force (M = Fd). When a balanced object is in rotational equilibrium, the Principle of Moments states that the total clockwise moment about any pivot equals the total anticlockwise moment about that pivot, a principle applied in levers and interlocking gear wheels to act as force multipliers. This topic also covers pressure in fluids (liquids and gases), where pressure acts normal to any surface (p = F / A) and increases with depth and fluid density according to p = hρg, generating the upward force of upthrust.

Electromagnetic (EM) waves are transverse waves that transfer energy from a source to an absorber without needing a material medium, travelling through a vacuum (and air) at the same constant speed of 3.0 x 10⁸ m/s. The electromagnetic spectrum is a continuous family of waves grouped into seven regions in order of decreasing wavelength and increasing frequency: Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, and Gamma rays. Examiners regularly test the wave equation (v = fλ), how alternating currents in aerials generate and receive radio waves (Higher Tier), the specific practical applications of each wave region, and the radiation dose hazards of high-frequency ionising waves (UV, X-rays, and gamma rays).

Refraction is the change in direction of a wave when it crosses a boundary from one transparent medium into another at an angle, caused by a change in wave speed (and wavelength, while frequency stays constant). In Triple Science GCSE Physics, refraction through glass is used by convex (converging) and concave (diverging) lenses to form real or virtual images, analysed using ray diagrams and the magnification formula. This topic also encompasses the required practicals for glass block refraction and investigating infrared emission and absorption using a Leslie's cube, alongside the physics of perfect black bodies and the Earth's radiative temperature balance.

When an electric current flows through a conducting wire, it produces a circular magnetic field around the wire; shaping the wire into a coil (a solenoid) concentrates the field lines inside to create an electromagnet with a uniform internal field and an external pattern identical to a bar magnet. When a current-carrying wire is placed inside an external magnetic field, the two magnetic fields interact to exert a force on the wire (the motor effect), governed by the equation F = BIL and Fleming's Left-Hand Rule. Examiners frequently test Fleming's Left-Hand Rule directions, F = BIL calculations, the role of the split-ring commutator in an electric motor, and how moving-coil loudspeakers convert AC signals into sound waves.

In Triple Science GCSE Physics, the generator effect (electromagnetic induction) is the exact inverse of the motor effect: moving an electrical conductor relative to a magnetic field so that it cuts through magnetic field lines induces a potential difference across the ends of the conductor (and an induced current if the circuit is complete). This principle powers electrical generators, where rotating a coil in a magnetic field produces either alternating current in an alternator (using slip rings) or direct current in a dynamo (using a split-ring commutator), as well as moving-coil microphones. Finally, transformers combine electromagnetic induction in two coils wound around a laminated soft iron core to step alternating voltages up or down according to V_p / V_s = n_p / n_s.

In Triple Science GCSE Physics, Space Physics explores how gravity pulls clouds of dust and hydrogen gas (nebulae) together to ignite nuclear fusion and form stars, whose eventual fate depends entirely on whether their mass is comparable to the Sun or much greater than the Sun. During a star's long, stable main sequence period, inward gravitational pull is balanced by outward thermal expansion pressure from nuclear fusion, while nuclear fusion and supernovae forge all the naturally occurring chemical elements in the universe. On a cosmological scale, observations of red-shift in the absorption spectra of distant galaxies show that more distant galaxies are receding faster, providing compelling evidence that the universe is expanding from an initial hot, dense Big Bang.