GCSE Physics Paper 1 WJEC Review

A set of vocabulary-style flashcards covering the key concepts, equations, and components for the GCSE Physics Paper 1 WJEC syllabus.

Micro (prefix)

A prefix meaning one-millionth, written in standard form as $\times 10^{-6}$. For example, $5\,\mu\text{m}$ is equivalent to $\frac{5}{1,000,000}\,m$.

Charge

The flow of electrical packets, often carried by electrons, measured in Coulombs $(C)$. One Coulomb is a group of many individual electrons.

Potential Difference (PD)

Also known as voltage, it tells us how much energy is transferred per Coulomb of charge. It is calculated using the equation $V = \frac{E}{Q}$, where $V$ is PD in volts, $E$ is energy in joules, and $Q$ is charge in coulombs.

Current

The rate of flow of charge, measured in Amps $(A)$. It is calculated using the equation $I = \frac{Q}{t}$, where $I$ is current, $Q$ is charge, and $t$ is time in seconds.

Voltmeter

A device used to measure Potential Difference. It must always be connected in parallel to the component being measured.

Ammeter

A device used to measure current. It must be connected in series (in line) with the component.

Resistance

The property of a component that resists the flow of charge, measured in Ohms $(\Omega)$. In a metal, it is caused by electrons colliding with a lattice of ions.

Ohm's Law

The relationship between potential difference, current, and resistance, expressed as $V = IR$.

Ohmic Conductor

A component, like a resistor at a constant temperature, where the current is directly proportional to the potential difference, resulting in a straight-line graph through the origin.

Filament Lamp

A non-ohmic component where resistance increases as the temperature increases due to more frequent collisions between electrons and vibrating ions. This creates a curved $I\text{-}V$ graph.

Diode

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

Series Circuit Rules

1. Current is the same for all components. 2. Total PD is shared between components. 3. Total resistance is the sum of all individual resistances ($R_{\text{total}} = R_1 + R_2 + ...$).

Parallel Circuit Rules

1. Potential difference is the same for every branch. 2. Current is shared between branches. 3. Adding more resistors in parallel lowers the total resistance.

Thermistor

A temperature-dependent resistor whose resistance decreases as the temperature increases.

LDR (Light Dependent Resistor)

A resistor whose resistance decreases as light intensity increases.

Electrical Power

The rate of energy transfer, calculated using $P = VI$ (Power = PD $\times$ Current) or $P = I^2 R$ (Power = Current squared $\times$ Resistance), measured in Watts $(W)$.

Direct Current (DC)

Current that only flows in one direction, typically supplied by batteries.

Alternating Current (AC)

Current that constantly reverses direction, supplied by mains electricity. In the UK, it has a frequency of $50\text{ Hz}$ and an average potential of $230\text{ V}$.

Live Wire (Brown)

The wire in a plug that carries the alternating potential from the supply, varying between positive and negative potentials.

Earth Wire (Yellow and Green)

A safety wire connected to the metal casing of appliances. It provides a low-resistance path to the ground to prevent electric shocks if a fault occurs.

Fuse

A safety device attached to the live wire designed to melt and break the circuit if the current exceeds a specific threshold (e.g., $3\text{ A}$, $5\text{ A}$, or $13\text{ A}$).

Step-up Transformer

A device used in the National Grid to increase voltage and decrease current, which reduces energy lost as heat in the cables.

Law of Conservation of Energy

Energy cannot be created or destroyed, only transferred from one store to another or to the surroundings.

Kinetic Energy ($KE$)

The energy of a moving object, calculated as $KE = \frac{1}{2}mv^2$, where $m$ is mass in kilograms and $v$ is speed in $\text{m/s}$.

Gravitational Potential Energy ($GPE$)

The energy stored in an object due to its height, calculated as $GPE = mgh$, where $g$ is gravitational field strength ($9.8$ or $10\text{ N/kg}$) and $h$ is height in meters.

Elastic Potential Energy ($EPE$)

The energy stored in a stretched or compressed spring, calculated as $EPE = \frac{1}{2}ke^2$, 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 $1\text{ kg}$ of a substance by $1^{\circ}\text{C}$. Calculated using $E = mc\triangle T$.

Efficiency

A measure of how much input energy is transferred usefully. Calculated as $\frac{\text{Useful Energy Out}}{\text{Total Energy In}}$.

Conduction

The transfer of heat in solids through the vibration of particles being passed along the material.

Convection

The transfer of heat in fluids (liquids and gases) where heated particles spread out, become less dense, and rise, creating a convection current.

Infrared Radiation

A type of electromagnetic wave that transfers thermal energy. It can travel through a vacuum and is absorbed/emitted best by dark, matte surfaces.

Longitudinal Waves

Waves where the oscillations are parallel to the direction of energy transfer, such as sound waves or seismic P-waves.

Transverse Waves

Waves where the oscillations are perpendicular to the direction of energy transfer, such as water waves, seismic S-waves, or light.

Wavelength ($\lambda$)

The distance between two consecutive peaks or identical points on a wave, measured in meters.

Frequency ($f$)

The number of waves that pass a point every second, measured in Hertz $(Hz)$. It is the reciprocal of the time period ($f = \frac{1}{T}$).

Wave Speed ($v$)

Calculations for how fast a wave travels, found using $v = f\text{ }\times\text{ }\triangle$ (Speed = Frequency $\times$ Wavelength).

Refraction

The change in direction of a wave as it moves from one medium to another (e.g., air to glass) and changes speed. If light slows down, it moves closer to the normal.

Total Internal Reflection (TIR)

The phenomenon occurring when the angle of incidence is greater than the critical angle, causing light to reflect entirely back into the denser medium. This is the basis of optic fibers.

Gas Pressure

Caused by gas particles colliding with the walls of a container. Increasing temperature or compressing the volume increases the frequency and force of these collisions.

Boyle's Law (Gas Equation)

In a gas at a constant temperature, pressure and volume are inversely proportional: $P_1V_1 = P_2V_2$.

The Motor Effect

The force experienced by a current-carrying wire when placed in a magnetic field, calculated using $F = BIl$, where $B$ is magnetic flux density in Tesla $(T)$, $I$ is current, and $l$ is length.

Fleming's Left Hand Rule

A way to find the direction of the force in the motor effect: Thumb = Force, First Finger = Magnetic Field (North to South), Middle Finger = Current.

The Generator Effect

The induction of a potential difference (and current in a complete loop) when a wire is moved through a magnetic field or a magnet is moved through a coil.