Fundamental Interactions

Key Stage 5

The fundamental interactions are the 4 ways in which subatomic particless may affect one another.

The fundamental interactions can cause subatomic particless to change direction or change from one subatomic particles into one or more other subatomic particles.

During the interactions certain properties of subatomic particless are conserved, including baryon number, lepton number, charge and strangeness (which is conserved in the strong interaction but not conserved in the weak interaction).

The four fundamental interactions are:

Strong Nuclear Interaction - Experienced only by hadrons and responsible for holding quarks together and holding protons and neutrons together in the atomic nucleus.
Weak Nuclear Interaction - Experienced by hadrons and leptons and responsible for decay of subatomic particles.
Electromagnetic Interaction - Experienced by particles with charge. This interaction is referred to as 'long range' as extends far beyond the range of atomic nuclei and is observed on macroscopic scales, but can be shielded by dielectric materials.
Gravitational Interaction - Experienced by all particles with mass. This interaction is extremely weak on the scale of atomic masses but is 'long range' and cannot be shielded, so accumulates with large numbers of atoms to be observable at macroscopic scales.