CBSE  /  Class 12  /  Physics  /  Electromagnetic Induction

  • 1. 
    When the magnetic field is parallel to a surface, then the magnetic flux through the surface is:

  • infinite
  • zero
  • small but not zero
  • large but not infinite.

  • 2. 
    The energy stored in a 50 mH inductor carrying a current of 4 A is:

  • 0.1 J
  • 0.4 J
  • 0.04 J
  • 0.01 J

  • 3. 
    The flux linked with a coif at any instant t is given by ∅ = 10t² - 50t + 250. The induced emf at t = 35 is:

  • 10 V
  • 190 V
  • -190 V
  • -10 V

  • 4. 
    Two coils of self inductance 2 mil and 8 mil are placed so close together that the effective flux in one coil is completely linked with other. The mutual inductance between these coils is :

  • 4 mH
  • 16 mH
  • 10 mH
  • 6 mH

  • 5. 
    The core of a transformer is laminated because:

  • rusting of core may be prevented
  • ratio of voltage in primary and secondary may be increased.
  • energy losses due to eddy current may be minimised
  • The weight of transformer may be reduced
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