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The B-H curve for a ferromagnet is shown...

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

A

2 mA

B

`20 mu A`

C

`1 mA`

D

`40 mu A`

Text Solution

Verified by Experts

The correct Answer is:
C
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Knowledge Check

  • A solenoid has 20 turns per cm. What is the value of the current that should be passed through the solenoid, to produce a magnetic field of 4 mT at its center?

    A
    `4/piA`
    B
    `5/piA`
    C
    `6/piA`
    D
    `8/piA`

  • An iron rod of volume 10^(-4) m^(3) and relative permeability 900 is placed inside a long solenoid wound with 6 turns/cm. If a current of 0.4 A is passed through the solenoid, the magnetic moment of the rod is

    A
    0.216 `Am^(2)`
    B
    2.16 `Am^(2)`
    C
    21.6 `Am^(2)`
    D
    `2.16 xx 10^(-2) Am^(2)`

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    A
    `10 AM^(2)`
    B
    `15 AM^(2)`
    C
    `20 AM^(2)`
    D
    `25 AM^(2)`

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