Electrical Machines
In DC machine, the armature windings are placed on the rotor because of necessity for

 commutation.
 electromechanical energy conversion.
 generation of voltage.
 development of torque.

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Electrical Machines
For a single phase capacitor start induction motor which of the following is valid?

  Rotation can be changed by reversing main winding terminals.
 Direction of rotation cannot be changed.
 None of these.
 Rotation can be changed by interchanging supply terminals.

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Electrical Machines
Short circuit test is performed on a transformer with a certain impressed voltage at rated frequency. If the short circuit test is now performed with the same magnitude of impressed voltage, but at frequency higher than the rated frequency then

 The magnitude of current will decrease but the power factor will increase.
 The magnetude of current will increase, but power factor will decrease.
 The magnitude will both increase.
 The magnitude of circuit as well as the power factor will decrease.

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