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
(D) All of the above
electromagnets generally function as holding magnets ?
(A) Tractive
(B) Portative
(C) Either of the above
(D) None of the above
In D.C. machines the width of the duct is usually_____________?
(A) 4 mm
(B) 6 mm
(C) 8 mm
(D) 10 mm
In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?
(A) increase
(B) decrease
(C) either of the above
(D) none of the above
Which of the following methods may be adopted to reduce the effects of armature reaction ?
(A) Increase in length of air gap at pole tips
(B) Increasing reluctance of pole tips
(C) Compensating windings
(D) Interpoles
(D) All of the above
In D.C. machines the number of slots per pole usually lies___________?
(A) between 2 to 4
(B) between 6 to 8
(C) between 9 to 16
(D) between 20 to 30
In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?
(A) 5 percent
(B) 10 percent
(C) 15 percent
(D) 30 percent
(D) none of the above
Power transformers have rating_______________?
(A) equal to 50 kVA
(B) equal to 100 kVA
(C) above 200 kVA
(D) none of the above
____________are always double layer type?
(A) Closed windings
(B) Open windings
(C) Either of the above
(D) None of the above