The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is

The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 1.0.

The back e.m.f. is the voltage generated by the motor itself, and it is proportional to the speed of the motor. The applied voltage is the voltage that is supplied to the motor. When the back e.m.f. is equal to the applied voltage, the motor is said to be operating at “full load”. At this point, the motor is developing its maximum mechanical power.

If the back e.m.f. is less than the applied voltage, the motor will be developing less than its maximum mechanical power. This is because the motor will be drawing more current than it needs to, and the excess current will be converted into heat.

If the back e.m.f. is greater than the applied voltage, the motor will be developing more than its maximum mechanical power. This is because the motor will be generating more power than it needs to, and the excess power will be converted into heat.

Therefore, the mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 1.0.