Correct option is B
Back EMF: When a DC motor rotates, the rotating coils of wire cut through magnetic fields, inducing an electromotive force (EMF) within the coils. This induced EMF is called "back EMF" because it opposes the applied voltage that is driving the motor.
Lenz's Law: This fundamental principle in electromagnetism states that the direction of an induced current is such that it opposes the change in magnetic flux that caused it. In the case of a DC motor, the back EMF opposes the applied voltage, effectively acting as a brake and limiting the current flow.
