(1) An e.m.f. is induced in a conductor when the magnetic field surrounding it changes.
(2) The magnitude of the e.m.f. is proportional to the rate of change of the field.
(3) The sense of the induced e.m.f. depends on the direction of the rate of change of the field.

• Abelian group
• aberration
• abscissa
• absolute
• absolute expansivity
• absolute humidity
• absolute permittivity
• absolute pitch
• absolute temperature
• absolute value
• absolute zero
• absorptance
• absorption
• absorption coefficient
• absorption spectrum
• absorptivity
• abundance
• acceleration
• acceleration of free fall
• accelerator
• acceptor
• acceptor levels
• accommodation
• accretion disc
• accumulator