Magnetic moment of bar magnet is $$2 M$$. The work done to turn the magnet by $$90^{\circ}$$ of magnet in direction of magnetic field $$B / 2$$ will be

If the B - H curves of two samples of X and Y of iron are as shown below, then which one of the following statement is correct?

A long cylindrical iron core of cross-sectional area 5 cm² is inserted into a long solenoid having 4000 turns/meter and carrying a current 5 A. The magnetic field inside the core is $$\pi$$ T. Find the pole strength developed.