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QJEEM18Ph0a1c: JEE Main 2018 Physics - Class 12 JEEM18Ph0a1c Solution: The - curve for a ferromagnet is shown in the figure. The…

The BB - HH curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solended with 10001000 turns/cm. The current that should be passed in the solended to demagnetise the ferromagnet completely is :

JEE Main 2018 (Online) 15th April Morning Slot Physics - Magnetic Properties of Matter Question 54 English

Multiple Choice Options

  • A 11 mAmA
  • B 22 mAmA
  • C 20 μA20\,\mu A
  • D 40 μA40\,\mu A

Step-by-Step Verified Solution

Given that,

In the solenoid there is 1000 turns in 1 cm.

∴    \therefore\,\,\,\, In 100 cm or 1 m no of turns

= 1000 ×\times 100 = 105 turns/m

∴    \therefore\,\,\,\, No of turns, n = 105

Correctivity of ferromagnet, H = 100 A/m

As we know,

H = n I

∴    \therefore\,\,\,\, I = 100105=1mA{{100} \over {{{10}^5}}} = 1mA

∴    \therefore\,\,\,\, Current to demagnetise the ferromagnet = 1 mA.

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