1.

The coercitivity of a small magnet where the ferromagnet gets demagnetized is `3 xx 10^(3) Am^(-1)`. The current required to be passed in a solenoid of length `10 cm` and number of turns `100`, so that the magnet gets demagnetized when inside the solenoid , is :A. 30mAB. 60mAC. 3AD. 6A

Answer» Correct Answer - C
For solenoid , the magnetic field needed to be magnetised the magnet , `B=mu_(0)nl`
[ where , `n=100, l=10 cm =(10)/(100)m=0.1m`]
`implies 3 xx 10^(3) =(100)/( 0.1) xx l `
`implies l=3A `


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