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An air gap is usually inserted in magnetic circuits toAn air gap is usually inserted in magnetic circuits to
The answer is:
C. prevent saturation


The relative permeability of a ferromagnetic material isThe relative permeability of a ferromagnetic material is
The answer is:
D. more than 100 or 1000


The unit of magnetic flux isThe unit of magnetic flux is
The answer is:
B. weber


Permeability in a magnetic circuit corresponds to______ in an electric circuitPermeability in a magnetic circuit corresponds to______ in an electric circuit.
The answer is:
C. conductivity


Point out the wrong statement.Magnetic leakage is undesirable in electric machines because itPoint out the wrong statement.Magnetic leakage is undesirable in electric machines because it
The answer is:
A. lowers their power efficiency


Relative permeability of vacuum is 

Permanent magnets are normally made ofPermanent magnets are normally made of
The answer is:
A. alnico alloys


Energy stored by a coil is doubled when its current is increased by percentEnergy stored by a coil is doubled when its current is increased by percent.
The answer is:
C. 41.4


Those magnetic materials are best suited for making armature and transformer coreswhich have____permeability and_______hystersis lossThose magnetic materials are best suited for making armature and transformer coreswhich have____permeability and_______hystersis loss.
The answer is:
C. high, low


The rate of rise of current through an inductive coil is maximumThe rate of rise of current through an inductive coil is maximum
The answer is:
B. at the start of the current flow


When both the inductance and resistance of a coil are doubled the value ofWhen both the inductance and resistance of a coil are doubled the value of
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_______VsThe 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 answer is:
B. 20


A material for good magnetic memory should haveA material for good magnetic memory should have
The answer is:
D. high retentivity


Conductivity is analogous toConductivity is analogous to
The answer is:
C. permeability


In a magnetic material hysteresis loss takes place primarily due toIn a magnetic material hysteresis loss takes place primarily due to
The answer is:
D. it high retentivity


Those materials are well suited for making permanent magnets whichhave______retentivity and _______coercivityThose materials are well suited for making permanent magnets whichhave______retentivity and _______coercivity
The answer is:
B. high, high


If the area of hysteresis loop of a material is large, the hysteresis loss in this materialwill beIf the area of hysteresis loop of a material is large, the hysteresis loss in this materialwill be
The answer is:
C. large


Hard steel is suitable for making permanent magnets becauseHard steel is suitable for making permanent magnets because
The answer is:
A. it has good residual magnetism


Silicon steel is used in electrical machines because it hasSilicon steel is used in electrical machines because it has
The answer is:
C. low hysteresis loss


Conductance is analogous toConductance is analogous to
The answer is:
A. permeance

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