____________are used for construction of core of electromagnets?

A. Soft magnetic materials
B. Hard magnetic materials
C. Either a. or b.
D. None of the above

Tractive magnets are operated from____________?

A. c. supply
B. D.c. supply
C. Either a.c. or d.c. supply
D. None of the above

Which of the following is the commonly used type of electromagnets ?

A. Flat-faced armature type
B. Horse shoe type
C. Flat-faced plunger type
D. All of the above

The design of electromagnets is based upon which of the following fundamental equations ?

A. force equation
B. magnetic circuit equation
C. heating equation
D. voltage equation

electromagnets generally function as holding magnets ?

A. Tractive
B. Portative
C. Either of the above
D. None of the above

By which of the following methods motor rating for variable load drives can be determined ?

A. method of average losses
B. equivalent current method
C. equivalent torque method
D. equivalent power method

The value of exciting or magnetizing current depends upon which of the following factors ?

A. Total m.m.f. required
B. The number of turns in the exciting winding
C. The way in which the winding is distributed
D. All of the above

By which of the following methods the temperature rise of windings and other parts may be determined ?

A. Thermometer method
B. Resistance method
C. Embedded temperature detector method
D. Any of the above

Which of the following methods is used for air cooling of turbo-alternators ?

A. One sided axial ventilation
B. Two sided axial ventilation
C. Multiple inlet system
D. All of the above

The slot leakage can be calculated by making which of the following assumptions ?

A. The current in the slot conductors is uniformly distributed over their cross-section
B. The leakage path is straight across the slot and around the iron at the bottom
C. The permanence of air paths is only considered. the reluctance of iron paths is assumed as zero
D. All of the above