Electrical Machines
The teeth in the armature of a DC machines are sometimes skewed. This is done to reduce

 eddy electric current loss.
 hysteresis loss.
 vibrations.
 copper loss.

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Electrical Machines
Consider the following statements regarding dc machines : 1. possible resistance of shunt-field winding is 1 Ω 2. possible resistance of series-field winding is 1 Ω 3. electrographite brushes are used for 230 V, 10 A machines 4. Copper-graphite brushes are used for 230 V, 10 A machines 5. Possible armature-circuit resistance is 1 Ω From these, the correct statements are

 1, 4
 2, 4 ,5
 2, 3 , 5
 1, 3, 5

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Electrical Machines
The synchronous motor can be started by

  coupling it with a DC compound motor.
  coupling it with a small AC induction motor called the pony motor.
  any of the above methods.
  providing damper winding in its rotor circuit.

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Electrical Machines
Due to magnetic saturation, the flux per pole in a DC machine without brush shift

 increases in generators but decreases in motor with load.
  decreases in both generators and the motors with load.
 decreases in generators and increases in motor with load.
 increases in both the generators and the motors with load.

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