Question

The coercivity of a small magnet where the ferromagnet gets demagnetized is $3\times {10}^{3}A{m}^{-1}$. The current required to be passed through the solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is:

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

Answer 1

The correct option is A 3 A

${\mu }_{0}H={\mu }_{0}m$. Hence $3\times {10}^3=\frac{100}{0.1}\times i\Rightarrow i=3A$