AMPLITUDE (instantaneous voltage) of a coil is found by the formula:
PHASE or PHASE ANGLE is the angle that exists between the starting position of a vector
generating the sine wave and its position at a given instant.
FREQUENCY is the rate at which the vector rotates.
HETERODYNING is the process of mixing two different frequencies across a nonlinear impedance
to give the ORIGINAL frequencies, a SUM frequency, and a DIFFERENCE frequency.