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NTA Abhyas JEE Main2020PhysicsMagnetic Properties of MatterPractice

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 demagnetise 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

Coercivity of ferromagnet, H = 100   A / m . n × I = 100 I = 100 10 5 = 1   m A

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