A Level Physics Key
Definitions 2026 | Study
Guide, Key Terms, Practice
Questions, Answers,
Rationales & Exam Review
| Complete Ethics Study
Guide
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
,Hypothesis A testable prediction, often implied by a theory
Theory A hypothesis that has been tested with a significant amount of data
Test A way to gather a set of results
Absolute Refractive Index the ratio of the speed of light in a vacuum compared with the speed of light in a
medium
Absolute Uncertainty The uncertainty in a measurement expressed in the unit you are measuring in
Absorption (fibre optics) Where some of the energy of a fibre-optic is absorbed by the material of the fibre
optic
Acceleration The rate at which velocity changes
Accurate Result A result that is very close to the true answer
Alpha Decay Decay where an unstable atom releases an alpha particle
Alpha Particle particle emitted by a radioactive source that contains two protons and two neutrons
Ammeter A device used to measure current in a circuit
Amplitude For a wave or vibration, the maximum displacement on either side of the equilibrium
(midpoint) position.
, Angle of Incidence The angle between the incident ray and the normal
Angle of Refraction The angle between the refracted ray and the normal
Annihilation When a particle meets its antiparticle and their mass gets turned into energy in the
form of gamma ray photons
Anomalous Result an extremely high or low result that does not match the other results in a set of
scores
Antinode A point of maximum amplitude on a stationary wave
Average Velocity The change in velocity divided by the time taken
Baryon Hadron made up of 3 quarks
Baryon Number The number of baryons in a particle
Definitions 2026 | Study
Guide, Key Terms, Practice
Questions, Answers,
Rationales & Exam Review
| Complete Ethics Study
Guide
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
,Hypothesis A testable prediction, often implied by a theory
Theory A hypothesis that has been tested with a significant amount of data
Test A way to gather a set of results
Absolute Refractive Index the ratio of the speed of light in a vacuum compared with the speed of light in a
medium
Absolute Uncertainty The uncertainty in a measurement expressed in the unit you are measuring in
Absorption (fibre optics) Where some of the energy of a fibre-optic is absorbed by the material of the fibre
optic
Acceleration The rate at which velocity changes
Accurate Result A result that is very close to the true answer
Alpha Decay Decay where an unstable atom releases an alpha particle
Alpha Particle particle emitted by a radioactive source that contains two protons and two neutrons
Ammeter A device used to measure current in a circuit
Amplitude For a wave or vibration, the maximum displacement on either side of the equilibrium
(midpoint) position.
, Angle of Incidence The angle between the incident ray and the normal
Angle of Refraction The angle between the refracted ray and the normal
Annihilation When a particle meets its antiparticle and their mass gets turned into energy in the
form of gamma ray photons
Anomalous Result an extremely high or low result that does not match the other results in a set of
scores
Antinode A point of maximum amplitude on a stationary wave
Average Velocity The change in velocity divided by the time taken
Baryon Hadron made up of 3 quarks
Baryon Number The number of baryons in a particle
