Question

The $B-H$ curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with $1000 \, turns \, cm^{- 1}$ . The current that should be passed in the solenoid to demagnetise the ferromagnet completely is

• A. $2mA$
• B. $20?A$
• C. $1mA$
• D. $40?A$

Answer 1

Answer: (C)

$1mA$

Answer 2

Coercivity of ferromagnet, $H=100A/m$ . $n\times I=100$ $I=\frac{100}{10^{5}}=1 \, mA$