A small sphere of bismuth is hung between the closely spaced pole pieces of a strong…
PHYSICS · Multi-part · CBSE · Physics · Magnetism and Matter · Magnetism and Matter
Problem
A small sphere of bismuth is hung between the closely spaced pole pieces of a strong laboratory electromagnet. When the magnet is switched on, the sphere is observed to move towards the weaker field region, whereas an identical sphere of aluminium placed in the same arrangement moves towards the stronger field region.
(i) Identify the class of magnetic material to which bismuth and aluminium belong, giving reasons for each identification.
(ii) Explain qualitatively, on the basis of atomic magnetic dipoles, why the two spheres move in opposite directions in the non-uniform field.
(iii) The susceptibility of a paramagnetic material decreases as its absolute temperature increases. Explain this behaviour on the basis of molecular agitation.