Terms of the encyclopedia of physics beginning with A: 18.
- Aberration of light
- Aberrations of electron lenses
- Aberrations of optical systems
- Absolute practical electrical units
- Absolute systems of units
- Absolute temperature
- Absolute zero of temperature
- Absolutely neutral particle
- Adaptation
- Alignment
- Anechoic chamber
- Angle of attack
- Autocollimation
- Autocollimator
- Autoionisation (field ionisation)
- Availability
- Avalanche discharge
- Avogadro constant