Definitions and Concepts for WJEC (Eduqas) Physics A-level Component 3: Light and Nuclei

This set of flashcards includes key vocabulary terms and definitions from the WJEC (Eduqas) Physics A-level lecture on Light and Nuclei.

Alpha Radiation

The radiation of a particle containing two protons and two neutrons, strongly ionising, slow moving and positively charged.

Annihilation

The process of a particle and its antiparticle colliding and being converted into energy, releasing energy in two photons to conserve momentum.

Amplitude

A wave’s maximum displacement from its equilibrium position.

Antinode

A position of maximum displacement in a stationary wave.

Avogadro Constant

The number of particles that make up one mole of any gas.

Baryons

A class of hadron, made up of three quarks; the proton is the only stable baryon.

Becquerel

The unit of radioactive activity.

Beta-Minus Radiation

Radiation consisting of a high energy electron that is mildly ionising, fast moving and negatively charged.

Binding Energy

The amount of energy required to split a nucleus into all its separate constituent nucleons.

Coherent Source

Sources that have the same wavelength and frequency, with a fixed phase difference.

Critical Angle

The angle of incidence beyond which a wave will be totally internally reflected.

Diffraction

The spreading of a wave as it passes through a gap or around an obstacle of a similar magnitude to its wavelength.

Electromagnetic Interaction

An interaction between charged particles with infinite range, following the inverse square law.

Energy Levels

Defined and distinct energies at which electrons can exist in an atom.

Gamma Radiation

High energy photons that are weakly ionising, travel at the speed of light and have no charge.

Half-Life

The time it takes for half of the unstable nuclei in a sample to decay.

Photon

A packet of energy.

Quarks

Fundamental particles that interact via the strong interaction, can change flavor via the weak interaction.

Refraction

The changing of speed of a wave when it enters a different medium.

Total Internal Reflection

An effect that occurs in optical fibres where full reflection occurs at the boundary.

Weak Interaction

The force that causes flavour change in quarks and leptons, responsible for beta decay.