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

Answer

c

Explanation

(c) magnetic field in solenoid `B=mu_(0) ni`
`rArr (B)/(mu_(0))=ni` (Where n=number of turns per unit length)
`rArr(B)/(mu_(0))=(Ni)/(L) rArr 3xx10^(3)=(100i)/(10xx10^(-2))rArr i=3A`