Top 50+ Solved Magnetic Circuit MCQ Questions Answer
Q. An air gap is usually inserted in magnetic circuits to
a. increase m.m.f.
b. increase the flux
c. prevent saturation
d. none of the above
Q. The relative permeability of a ferromagnetic material is
a. less than one
b. more than one
c. more than 10
d. more than 100 or 1000
Q. Permeability in a magnetic circuit corresponds to______ in an electric circuit.
a. resistance
b. resistivity
c. conductivity
d. conductance
Q. Point out the wrong statement.Magnetic leakage is undesirable in electric machines because it
a. lowers their power efficiency
b. increases their cost of manufacture
c. leads to their increased weight
d. produces fringing
Q. Permanent magnets are normally made of
a. alnico alloys
b. aluminium
c. cast iron
d. wrought iron
Q. Energy stored by a coil is doubled when its current is increased by percent.
a. 25
b. 50
c. 41.4
d. 100
Q. Those magnetic materials are best suited for making armature and transformer coreswhich have____permeability and_______hystersis loss.
a. high, high
b. low, high
c. high, low
d. low, low
Q. The rate of rise of current through an inductive coil is maximum
a. at 63.2% of its maximum steady value
b. at the start of the current flow
c. after one time constant
d. near the final maximum value of current
Q. When both the inductance and resistance of a coil are doubled the value of
a. time constant remains unchanged
b. initial rate of rise of current is doubled
c. final steady current is doubled
d. time constant is halved
Q. A material for good magnetic memory should have
a. low hysteresis loss
b. high permeability
c. low retentivity
d. high retentivity
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