Magnetic Circuit MCQ

Test your knowledge with important Magnetic Circuit MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more Magnetic Circuit MCQs at Bissoy

• Conductivity is analogous to
  ক

  Retentivity

  খ

  Resistivity

  গ

  Permeability

  ঘ

  Inductance
• The property of a material which opposes the creation of magnetic flux in it is known as
  ক

  Reluctivity

  খ

  Magneto-motive force

  গ

  Permeance

  ঘ

  Reluctance
• The rate of rise of current through an inductive coil is maximum
  ক

  At 63.2% of its maximum steady value

  খ

  At the start of the current flow

  গ

  After one time constant

  ঘ

  Near the final maximum value of current
• Hysteresis loss least depends on
  ক

  Volume of material

  খ

  Frequency

  গ

  Steinmetz’s coefficient of material

  ঘ

  Ambient temperature
• The unit of reluctance is
  ক

  $$\frac{{{\text{Meter}}}}{{{\text{Henry}}}}$$

  খ

  $$\frac{{{\text{Henry}}}}{{{\text{Meter}}}}$$

  গ

  $${\text{Henry}}$$

  ঘ

  $$\frac{1}{{{\text{Henry}}}}$$
• Hard steel is suitable for making permanent magnets because
  ক

  It has good residual magnetism

  খ

  Its hysteresis loop has large area

  গ

  Its mechanical strength is high

  ঘ

  Its mechanical strength is low
• Energy stored by a coil is doubled when its current is increased by percent.
  ক

  25

  খ

  50.14

  গ

  41.4

  ঘ

  100
• The relative permeability of a ferromagnetic material is
  ক

  Less than one

  খ

  More than one

  গ

  More than 10

  ঘ

  More than 100 or 1000
• An air gap is usually inserted in magnetic circuits to
  ক

  Increase m.m.f.

  খ

  Increase the flux

  গ

  Prevent saturation

  ঘ

  None of the above
• The unit of retentivity is
  ক

  Weber

  খ

  Weber/sq. m

  গ

  Ampere turn/meter

  ঘ

  Ampere turns
• If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be
  ক

  Zero

  খ

  Small

  গ

  Large

  ঘ

  None of the above
• Silicon steel is used in electrical machines because it has
  ক

  Low coercivity

  খ

  Low retentivity

  গ

  Low hysteresis loss

  ঘ

  High coercivity
• When both the inductance and resistance of a coil are doubled the value of
  ক

  Time constant remains unchanged

  খ

  Initial rate of rise of current is doubled

  গ

  Final steady current is doubled

  ঘ

  Time constant is halved
• Reciprocal of reluctance is
  ক

  Reluctivity

  খ

  Permeance

  গ

  Permeability

  ঘ

  Susceptibility
• A material for good magnetic memory should have
  ক

  Low hysteresis loss

  খ

  High permeability

  গ

  Low retentivity

  ঘ

  High retentivity
• Permanent magnets are normally made of
  ক

  Alnico alloys

  খ

  Aluminium

  গ

  Cast iron

  ঘ

  Wrought iron
• Conductance is analogous to
  ক

  Permeance

  খ

  Reluctance

  গ

  Flux

  ঘ

  Inductance
• A ferrite core has less eddy current loss than an iron core because
  ক

  Ferrites have high resistance

  খ

  Ferrites are magnetic

  গ

  Ferrites have low permeability

  ঘ

  Ferrites have high hysteresis
• Permeability in a magnetic circuit corresponds to_________ in an electric circuit.
  ক

  Resistance

  খ

  Resistivity

  গ

  Conductivity

  ঘ

  Conductance
• In a magnetic material hysteresis loss takes place primarily due to
  ক

  Rapid reversals of its magnetization

  খ

  Flux density lagging behind magnetizing force

  গ

  Molecular friction

  ঘ

  It high retentivity
• Relative permeability of vacuum is
  ক

  1

  খ

  1 H/m

  গ

  $$4\pi \times {10^{ - 7}}$$

  ঘ

  $$\frac{1}{4}$$
• The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is ___________Vs
  ক

  50

  খ

  20

  গ

  0.05

  ঘ

  500
• Those magnetic materials are best suited for making armature and transformer cores which have ________permeability and _________hysteresis loss.
  ক

  High, high

  খ

  Low, high

  গ

  High, low

  ঘ

  Low, low
• Those materials are well suited for making permanent magnets which have ________ retentivity and ________ coercivity.
  ক

  Low, high

  খ

  High, high

  গ

  High, low

  ঘ

  Low, low
• Laminated cores, in electrical machines, are used to reduce
  ক

  Copper loss

  খ

  Eddy current loss

  গ

  Hysteresis loss

  ঘ

  All of the above
• The unit of magnetic flux is
  ক

  Henry

  খ

  Weber

  গ

  Ampere-turn/weber

  ঘ

  Ampere/metre
• Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it
  ক

  Lowers their power efficiency

  খ

  Increases their cost of manufacture

  গ

  Leads to their increased weight

  ঘ

  Produces fringing
• While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit?
  ক

  E.M.F.

  খ

  Current

  গ

  Current density

  ঘ

  Conductivity