Electrical Machines
The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

 48.0%.
 59.2%.
 88.8%.
 57.1%.

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Electrical Machines
Cogging in induction motor occurs when

 number of stator teeth - number of rotor teeth = even number.
 number of stator teeth - number of rotor teeth = negative number.
 number of stator teeth - number of rotor teeth = odd number.
 number of stator teeth - number of rotor teeth = 0.

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Electrical Machines
Two DC generators having equal open-circuit emfs but slight different load characteristics are operating in parallel, then

 the machine with more drooping characteristic will supply more load.
None of these
  the machine will share load equally.
  the machine with more drooping characteristic will supply less load.

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