Top 250+ Solved Electromagnetic Theory MCQ Questions Answer
Q. In a magnetic material hysteresis loss takes place primarily due to
a. rapid reversals of its magnetisation
b. flux density lagging behind magnetising force
c. molecular friction
d. it high retentivity
Q. Those materials are well suited for making permanent magnets whichhave______retentivity and _______coercivity.
a. low, high
b. high, high
c. high, low
d. low, low
Q. If the area of hysteresis loop of a material is large, the hysteresis loss in this materialwill be
a. zero
b. small
c. large
d. none of the above
Q. Hard steel is suitable for making permanent magnets because
a. it has good residual magnetism
b. its hysteresis loop has large area
c. its mechanical strength is high
d. its mechanical strength is low
Q. Silicon steel is used in electrical machines because it has
a. low co-ercivity
b. low retentivity
c. low hysteresis loss
d. high co-ercivity
Q. The property of a material which opposes the creation of magnetic flux in it is known as
a. reluctivity
b. magnetomotive force
c. permeance
d. reluctance
Q. While comparing magnetic and electric circuits, the flux of magnetic circuit is comparedwith which parameter of electrical circuit ?
a. E.m.f.
b. Current
c. Current density
d. Conductivity
Q. A ferrite core has less eddy current loss than an iron core because
a. ferrites have high resistance
b. ferrites are magnetic
c. ferrites have low permeability
d. ferrites have high hysteresis
Q. Hysteresis loss least depends on
a. volume of material
b. frequency
c. steinmetz co-efficient of material
d. ambient temperature
Q. Laminated cores, in electrical machines, are used to reduce
a. copper loss
b. eddy current loss
c. hysteresis loss
d. all of the above