Which of the following is represented by the area enclosed by a hysteresis loop?

The intensity of magnetisation $I$ is plotted against the magnetising field $H$ for different substances. The curves $A$ and $B$ shown in the adjoining figure are associated with

$A$ bar magnet has a coercivity of $4 \times 10^3 \text{ A m}^{-1}$. It is placed inside a solenoid of $12 \text{ cm}$ length and $60$ turns. The current that should be passed through the solenoid to demagnetize the bar magnet is: (in $\text{ A}$)

If the $B-H$ curves of two samples $P$ and $Q$ of iron are as shown below,then which one of the following statements is correct?

The coercivity of a magnet,where the ferromagnet gets completely demagnetized,is $3 \times 10^{3} \text{ A m}^{-1}$. The minimum current required to be passed in a solenoid having $1000 \text{ turns m}^{-1}$,so that the magnet gets completely demagnetized when placed inside the solenoid,is:

The coercivity of a magnet is $5 \times 10^3 \text{ A/m}$. The amount of current required to be passed in a solenoid of length $30 \text{ cm}$ and the number of turns $150$,so that the magnet gets demagnetized when placed inside the solenoid is ............. $A$.