Magnetic Circuit solved MCQs

Title
An air gap is usually inserted in magnetic circuits to An air gap is usually inserted in magnetic circuits to increase m.m.f. increase the flux prevent saturation none of the above discuss The answer is: C. prevent saturation
The relative permeability of a ferromagnetic material is The relative permeability of a ferromagnetic material is less than one more than one more than 10 more than 100 or 1000 discuss The answer is: D. more than 100 or 1000
The unit of magnetic flux is The unit of magnetic flux is henry weber ampereturn/weber ampere/metre discuss The answer is: B. weber
Permeability in a magnetic circuit corresponds to______ in an electric circuit Permeability in a magnetic circuit corresponds to______ in an electric circuit. resistance resistivity conductivity conductance discuss The answer is: C. conductivity
Point out the wrong statement.Magnetic leakage is undesirable in electric machines because it Point out the wrong statement.Magnetic leakage is undesirable in electric machines because it lowers their power efficiency increases their cost of manufacture leads to their increased weight produces fringing discuss The answer is: A. lowers their power efficiency
Relative permeability of vacuum is Relative permeability of vacuum is 1 1 H/m 1/4JI 4n x 10-' H/m discuss The answer is: A. 1
Permanent magnets are normally made of Permanent magnets are normally made of alnico alloys aluminium cast iron wrought iron discuss The answer is: A. alnico alloys
Energy stored by a coil is doubled when its current is increased by percent Energy stored by a coil is doubled when its current is increased by percent. 25 50 41.4 100 discuss The answer is: C. 41.4
Those magnetic materials are best suited for making armature and transformer coreswhich have____permeability and_______hystersis loss Those magnetic materials are best suited for making armature and transformer coreswhich have____permeability and_______hystersis loss. high, high low, high high, low low, low discuss The answer is: C. high, low
The rate of rise of current through an inductive coil is maximum The rate of rise of current through an inductive coil is maximum at 63.2% of its maximum steady value at the start of the current flow after one time constant near the final maximum value of current discuss The answer is: B. at the start of the current flow
When both the inductance and resistance of a coil are doubled the value of When both the inductance and resistance of a coil are doubled the value of time constant remains unchanged nitial rate of rise of current is doubled inal steady current is doubled time constant is halved discuss The answer is: A. time constant remains unchanged
The initial rate of rise of current through a coil of inductance 10 H when suddenlyconnected to a D.C. supply of 200 V is_______Vs The initial rate of rise of current through a coil of inductance 10 H when suddenlyconnected to a D.C. supply of 200 V is_______Vs 50 20 0.05 500 discuss The answer is: B. 20
A material for good magnetic memory should have A material for good magnetic memory should have low hysteresis loss high permeability low retentivity high retentivity discuss The answer is: D. high retentivity
Conductivity is analogous to Conductivity is analogous to retentivity resistivity permeability inductance discuss The answer is: C. permeability
In a magnetic material hysteresis loss takes place primarily due to In a magnetic material hysteresis loss takes place primarily due to rapid reversals of its magnetisation flux density lagging behind magnetising force molecular friction it high retentivity discuss The answer is: D. it high retentivity
Those materials are well suited for making permanent magnets whichhave______retentivity and _______coercivity Those materials are well suited for making permanent magnets whichhave______retentivity and _______coercivity low, high high, high high, low low, low discuss The answer is: B. high, high
If the area of hysteresis loop of a material is large, the hysteresis loss in this materialwill be If the area of hysteresis loop of a material is large, the hysteresis loss in this materialwill be zero small large none of the above discuss The answer is: C. large
Hard steel is suitable for making permanent magnets because Hard steel is suitable for making permanent magnets because it has good residual magnetism its hysteresis loop has large area its mechanical strength is high its mechanical strength is low discuss The answer is: A. it has good residual magnetism
Silicon steel is used in electrical machines because it has Silicon steel is used in electrical machines because it has low co-ercivity low retentivity low hysteresis loss high co-ercivity discuss The answer is: C. low hysteresis loss
Conductance is analogous to Conductance is analogous to permeance reluctance flux inductance discuss The answer is: A. permeance

Title