Electrical Machines
For 250 volt DC Shunt Motor the armature and field resistance are 0.5 ohm and 250 ohm respectively. What will be the back e.m.f. produced when it takes a load current of 21A.

 150 V.
 280 V.
 240 V.
 220 V.

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Electrical Machines
A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will

 increase to a value greater than 1.25 times 220 V
 increase to value lying between 220 V and 1.25 times 220 V
 increase to 1.25 times 220 V
 not change and remain at 220 V

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Electrical Machines
No load primary current in a transformer

 lags behind applied voltage somewhat less than 90Ã
 leads the applied voltage by exactly 90Â&
 leads the applied voltage somewhat less than 90Ã&
 lags behind applied voltage by exactly 90Â&am

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Electrical Machines
An alternator is feeding an infinite busbar. Its prime mover is suddenly shutdown. The alternator will

 come to stand still.
 start working as induction motor.
 continue to work as alternator but the direction of rotation will reverse.
 continue to work as synchronous motor with same direction of rotation.

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