Electrical Machines
The residual magnetism of a self-excited dc generator is lost. To build up its emf again

 the field winding must be replaced
 the armature connection must be reversed
 the field winding connection must be reversed
 field winding must be excited by low voltage dc supply

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Electrical Machines
In a step down transformer which one of the following statements is true?

 Secondary power is less than primary power.
 Secondary current is less than primary current.
 Number of secondary turns is more than that of primary.
  Number of secondary turns is less than primary turns.

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Electrical Machines
The speed of a DC series motor is

 Inversely proportional to the armature current.
 Proportional to the armature current.
 Proportional to field current.
 Proportional to the square of the armature current.

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