Electrical Machines Objective Questions – Set 18

Lamination of core are generally made of

When Flemings right hand rule to find the direction of induced emf, the thumb points towards

Width of a carbon brush should be equal to

The number of brushes in a commutator depends on

The teeth in the armature of a DC machines are sometimes skewed. This is done to reduce

In an ideal DC generator the regulation is

If B is flux density, l the length of the conductor and v the velocity of the conductor, then emf is given by

The resistance of armature winding depends on

Armature of DC machine is made of

Copper brushes in DC machine are used

In a DC generator if field winding attains the critical resistance

07․ The polarity of a DC generator can be reversed by

The purpose of providing dummy coils in a generator is

In a DC generator, if P be the number of poles and N be the rpm of the rotor, then frequency of magnetic reversals will be

In a DC machine

In Dc machine, the armature windings are placed on the rotor because of necessity for

The insulating material used between the commutator segments is normally

In Dc generators, electric current to the external circuit from armature is given through

The bearings used to support the rotor shafts are generally

Poles of DC machine are often laminated to

In DC generators, the brushes remain in contact with conductors which

The emf induced in a conductor rotating in a bipolar field is

The armature of DC generator is laminated to

The ventilating ducts in most of DC machine are

The armature of DC machine is made of silicon steel lamination to

The brushes of a DC machine should be placed on the

In a commutator

If field current is decreased in shunt dc motor, the speed of the motor

What are slot wedges in a DC machine made of?

A DC generator beyond critical resistance will generate