where 
is the peak value or amplitude of the current, 
is the angular frequency, 
is the phase constant and 
is called the phase of the current. [P5.4, P5.5]
is: an electric current which changes magnitude and direction in a regular periodic way. [P5.4, P5.5]
often is: sinusoidal, i.e. it may be described by the formula where is the peak value or amplitude of the current, is the angular frequency, is the phase constant and is called the phase of the current. [P5.4, P5.5]
may also be described: using complex quantities, so in the sinusoidal case 
[P5.5]
more generally refers: to other associated electrical quantities whose direction varies with time, e.g. a.c. voltage. [P5.4]
is abbreviated: AC at the beginning of a sentence, and a.c. elsewhere. [P5.4]
Copyright 1997, The Open University