☰ Electrical Engineering Material (Electrical Engineering) - MCQs

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Q25.

When a paramagnetic substance is magnetized, there are small changes in dimensions. The phenomena is called

  • A. hysteresis
  • B. magnetostriction
  • C. diamagnetism
  • D. dipolar relaxation

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Q26.

the phenomena of restriction occurs when ferromagnetic substance is magnetized resulting in

  • A. heating
  • B. small changes in the dimensions
  • C. small changes in its crystal structure
  • D. some change in mechanical properties

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Q27.

magnetostriction is a phenomenon of

  • A. generation of electricity in ferromagnetic materials
  • B. generation of magnetism in conductors
  • C. changing permeability of ferromagnetic materials during magnetization
  • D. change in physical dimensions of ferromagnetic materials during magnetization

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Q28.

core of an electromagnet should have

  • A. low coercivity
  • B. high susceptibility
  • C. both a and b
  • D. none of these

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Q29.

the electromagnet is made of

  • A. soft iron core
  • B. steel core
  • C. soft iron core wrapped in a coil of fine wire with current flowing through it
  • D. any of the above methods

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Q30.

the magnetic field required to reduce the residual magnetization to zero is called

  • A. retentivity
  • B. coercivity
  • C. hysteresis
  • D. saturation

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