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 :

Options

A. `3A`
B. `6A`
C. `30mA`
D. `60mA`

Answer

A

Explanation

Here, coercivity of given magnet
`=B/mu_0=3xx10^3Am^-1`
As `B=(mu_0NI)/(L)`
or `I=(BL)/(mu_0N)=((3xx10^3)xx0*1)/(100)=3A`