Electrical Machines
Induction motors normally use cast aluminium rotor because aluminium is

  easy to cast owing to its low melting point and is easily available.
  cheaper in cost.
  lighter in weight.
  of low resistivity.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
A dc shunt generator, when commissioned after a major repair of the field system, failed to build Up voltage. It was because

 there was a break in the armature circuit
 field system lost residual magnetism
 field resistance was higher than critical resistance
 field winding was wrongly connected

ANSWER DOWNLOAD EXAMIANS APP