The shaft torque of a dc motor is less than the electromagnetic torque because of
A. mechanical losses.
B. hysteresis losses.
C. ohmic losses.
D. eddy current losses.
Answer: B
Share your understanding of this question with the correct explanation.
Explanation:
The shaft torque of a DC motor is less than the electromagnetic torque due to various losses, including hysteresis losses. Hysteresis losses occur in the magnetic materials of the motor’s core due to the energy dissipated during the magnetization and demagnetization cycles. These losses result in a reduction of the overall torque output of the motor.
Mechanical losses (option A) also contribute to the difference between the electromagnetic torque and the shaft torque, but they are not the primary factor in this case. Ohmic losses (option C) are associated with the resistance of the motor’s windings and are typically minimized in a well-designed DC motor. Eddy current losses (option D) occur in the laminated core of an AC motor and are not significant in a DC motor.