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Electromagnetic Induction — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsElectromagnetic Induction1 Mark
MCQ
A metal plate is getting heated. It can be because:
  • A
    A direct current is passing through the plate.
  • B
    It is placed in a time varying magnetic field.
  • C
    It is placed in a space varying magnetic field, but does not vary with time.
  • D
    A current (either direct or alternating) is passing through the plate.
✓

Answer

  1. A direct current is passing through the plate.
  2. It is placed in a time varying magnetic field.
  1. a current (either direct or alternating) is passing through the plate.

Solution:

Key concept: Eddy Current: When a changing magnetic flux is applied to a bulk piece of conducting material, then circulating currents called eddy currents are induced in the material. Because the resistance of the bulk conductor is usually low, eddy currents often have large magnitudes and heat up the conductor.

  1. These are circulating currents like eddies in water.
  2. Experimental concept is given by Focault, hence also named as "Focault current".
  3. The production of eddy currents in a metallic block leads to the loss of electric energy in the form of heat.
  4. By lamination, slotting processes, the resistance path for circulation of eddy current increases, resulting into weakening them and also reducing losses causes by them.

​​​​​​​

A metal plate is getting heated when a DC or AC current is passed through the plate, known as heating effect of current. This current (called eddy current) is induced in the plate when a metal plate is subjected to a time varying magnetic field, i.e., the magnetic flux linked with the plate changes and eddy currents comes into existence which make the plate hot.

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