Electrical Machines
A 4 pole wave wound dc motor having flux per pole of 9.56 X 10-3 Wb contains 460 armature conductors. Calculate the back emf produced when it is running at a speed of 1500 rpm.

 240 volt.
 230 volt.
 440 volt.
  220 volt.

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Electrical Machines
If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

 both hysteresis loss(Ph) and eddy current loss(Pe) will increase
 Ph will decrease but Pe will remain same
 Pe will increase but Ph will decrease
 Ph will increase but Pe will decrease

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