Two identical loss less series motors connected in series across a dc supply voltage, runs at speed of N1 and N2, then ratio of their output power is
A. N12 : N22.
B. N1 : N2.
C. 1 : 1.
D. none of the above.
Answer: B
Share your understanding of this question with the correct explanation.
The correct answer is B. N1 : N2.
The output power of a motor is given by the product of its speed (N) and torque (T). Since the motors are identical and lossless, the torque produced by each motor will be the same.
Therefore, the ratio of their output power can be determined by the ratio of their speeds:
Output power ratio = N1 : N2
This means that the output power of the motor running at speed N1 is in the same ratio as the output power of the motor running at speed N2.
The other options (N12 : N22, 1 : 1, none of the above) are not the correct ratios for the output power of the series-connected motors. The correct ratio is determined solely by the ratio of their speeds.