  Magnetic nulls are locations where the magnetic field vanishes. Nulls are the
location of magnetic reconnection, and they determine to a large degree the
magnetic connectivity in a system. We describe a novel approach to
understanding movement, appearance, and disappearance of nulls in magnetic
fields. This approach is based on the novel concept of isotropes, or lines
where the field direction is constant. These lines are streamlines of a vector
field whose flux is sourced by the topological indices of nulls, and can be
conceptualized as corresponding "lines of force" between nulls. We show how
this topological approach can be used to generate analytical expressions for
the location of nulls in the presence of external fields for dipoles and for a
field defined by the Hopf fibration.
