The figure illustrates how $B$,the flux density,inside a sample of ferromagnetic material varies with external magnetic field $B_0$. For the sample to be suitable for making a permanent magnet,

Magnetic hysteresis is exhibited by magnetic materials which are

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

What is Curie temperature? And what is retentivity?

$A$ metal rod is subjected to cycles of magnetisation at the rate of $42 \ Hz$. The density of the metal is $6 \times 10^3 \ kg \ m^{-3}$ and its specific heat capacity is $0.1 \times 10^3 \ cal \ kg^{-1} \ ^{\circ}C^{-1}$. If the area of its $B-H$ loop corresponds to an energy density of $10^{-2} \ J \ m^{-3}$,then the rise in its temperature in one minute is: (in $^{\circ} C$)

The area of the hysteresis loop of a material is equivalent to $250 \, J$. When $10 \, kg$ of the material is magnetized by an alternating field of $50 \, Hz$, what is the energy lost in one hour? (Given: density of the material is $7.5 \, g/cm^3$)