Electrical Machines
A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight

 180.
  150.
 160.
 170.

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Electrical Machines
In speed control of DC Series motor, speed lower than the rated speed can be obtained by

 Connecting an additional resistance in stator circuit.
 Connecting an additional resistance in the field circuit.
 Connecting an additional resistance in the armature circuit.
 Any of the above.

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Electrical Machines
With the increase in speed of a DC motor

 both back emf as well as line current increase.
 back emf falls and line current increases.
 back emf increases but line current falls.
 both back emf as well as line current fall.

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