Answer the following questions .
a. Why does a paramagnetic sample display greater magnetisation (for the same magnetising field) when cooled ?
b. Why is diamagnetism , in contrast , almost independent of temperature ?
c. If a toroid uses bismuth for its core, will the the field in the core be (slightly ) greater or (slightly ) less than when the core is empty ?
d. Is the permeability of a ferromagnetic material independent of the magnetic field ? If not, is it more for lower or higher fields ?
e. Magnetic field lines are always nearly normal to the surface of ferreomgnet at every point . (This fact is analogous to the static electric field lines being normal to the surface of conductor at every point). Why ?
f. Would the maximum possible magnetisation of paramagnetic sample be of the same order of magnitude as the magnetisation of ferromagnet ?

Explanation

As the paramagnetic substance is cooled, its atomic dipoles tend to get aligned with the magnetisation field . So it displays a greater magnetisation when cooled . The magnetisation of a diamagnetic substance is independent of temperature .