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The B - H curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with 1000 turns cm - 1 . The current that should be passed in the solenoid to demagnetize the ferromagnet completely is,

Options

  1. A2   mA
  2. B20   μA
  3. C1   mA
  4. D40   μA

Correct answer

C. 1   mA

Step-by-step solution

The coercivity of ferromagnet, H = 100   A   m - 1 , n × I = 100 ⇒ I = 100 10 5 = 1   m A .

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