Introduction When waves pass through a narrow gap, they spread out.

Energy Levels & Photon Emission

Introduction When white light from a tungsten filament is passed through a prism, the light is dispersed into its component colours, as illustrated in Figure 1.

Photoelectric Effect

Introduction Protons, neutrons and electrons that move around the nucleus constitute an atom, as illustrated in Figure 1.

Particle & Radiation

Introduction The atoms of all elements are made up of three particles called protons, neutrons and electrons.

Quarks & Anti-Quarks

Introduction In the classification of subatomic particles, as illustrated in Figure 1, Hadrons (Mesons and Baryons) are made up of three smaller particles called quarks.

Stable & Unstable Nuclei

Introduction An atom contains an equal number of positively charged protons and negatively charged electrons and their charges balance.

Particle, Antiparticle & Photons

Introduction Every particle has an antiparticle, according to the standard model for describing fundamental particles and interactions.