A mathematical analysis of the operation of a phonic motor is presented. Expressions are developed for the motor currents and voltages, power output, efficiency, etc. Both polarized and unpolarized motors are treated, and operation from high- and low-impedance sources is considered. A method for obtaining the motor constants experimentally is given and the predicted power output is compared with experimental results. Power ripple and motor hunting are both analysed. The possibility of multi-phase motors is discussed and some applications of phonic motors are described.