In a motor, the counter emf voltage induced in the armature causes what effect on the source current?

In a motor, the counter electromotive force (emf) generated in the armature acts to oppose the applied voltage from the power source. This phenomenon occurs because as the armature rotates, it generates its own voltage due to Faraday's law of electromagnetic induction. The induced counter emf is proportional to the speed of the motor; the faster the motor spins, the higher the counter emf.

This counter emf effectively reduces the net voltage that drives the current through the armature windings. As a result, the total current drawn from the power supply decreases. When the motor reaches a steady state, the counter emf stabilizes to a point where it significantly opposes the applied voltage, allowing the current to decrease to a steady level that corresponds to the motor's load and operational efficiency.

Thus, the presence of counter emf in a motor leads to a decrease in the source current as it limits the amount of current flowing into the armature. This relationship is essential in understanding motor operation, particularly in applications where controlling the motor speed and efficiency is crucial.