Electromagnetic Induction MCQs

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Hysteresis losses can be reduced by

  • A. using grain-oriented silicon steel
  • B. increasing the frequency of the field
  • C. laminating the core
  • D. none of these
  • Correct Answer: Option A

A degaussing is the process of

  • A. removing gases from materials
  • B. removal of magnetic impurities
  • C. demagnetizing metallic part
  • D. magnetizing nonmettalic part
  • Correct Answer: Option C

According to Hysteresis law, hysteresis loss in a material is proportional to

  • A. B^1.2
  • B. B^1.6
  • C. B^0.6
  • D. B^3.6
  • Correct Answer: Option B

The area of hysteresis loop represents hysteresis loss in

  • A. J/ m^3/s
  • B. J/cycle
  • C. J/s
  • D. J/m^3
  • Correct Answer: Option A

In electrical machines, laminated cores are used with a view of reducing

  • A. eddy current loss
  • B. copper loss
  • C. hysteresis loss
  • D. windage loss
  • Correct Answer: Option A

It is difficult to magnetize steel because its

  • A. low permeability
  • B. high retentivity
  • C. high permeability
  • D. high density
  • Correct Answer: Option A

The coupling coefficient denotes

  • A. the degree of magnetic linkage
  • B. whether the reluctance remains constant
  • C. the variation of inductance between the two coils
  • D. whether the flux linkage is constant
  • Correct Answer: Option A

Coupling coefficient k, a term much used in radio work can be obtained from

  • A. K = M√(L1L2)
  • B. K = M√(L1/L2)
  • C. K = M/√(L1L2)
  • D. K = ML1L2
  • Correct Answer: Option B

The value of mutual inductance in terms of self inductance of the two coils L1 and L2 is proportional to

  • A. L1L2
  • B. L1/L2
  • C. √(L1/L2)
  • D. √(L1L2)
  • Correct Answer: Option D

The mutual inductance of two coils is maximum when the coils are

  • A. inclined at an angle 45 degrees
  • B. at right angle to each other
  • C. facing each other
  • D. touching each other
  • Correct Answer: Option D