Put another way: every electric motor is also a generator and vice-versa. If you induce the motor to absorb energy from the power supply rather than emit it, th

Put another way: every electric motor is also a generator and vice-versa. If you induce the motor to absorb energy from the power supply rather than emit it, that energy has to go somewhere. As usual, when not specified, "somewhere" tends to mean heat, sound, and inelastic deformation of anything in relatively close proximity to the excess energy.