S is the surface of a lump of magnetic material.

Options

A. Lines of `overset(to)(B)` are necessarily continuous across s.
B. Some lines of `overset(to)(B)` must be discontinuous across S.
C. Lines of `overset(to)(H)` are necessarily continuous across S.
D. Lines of `overset(to)(H)` cannot all be continuous across S.

Answer

A, D

Explanation

Magnetic field lines forms continuous closed loops.
Magnetic intensity outside magnet `(H) = (B)/( mu_0)` and for inside the magnet `H= (B)/(mu_(0) mu_(r) )` (where `mu_r` is the relative permeability of material).
Magnetic intensity H forms continuous magnetic field lines hence field lines of B need to pass from S.
Magnetic intensity varies for inside and outside of lump. So lines of H can not all be continuous across S.