discontinuities and eddy currents

NEWO

How does an eddy current vary in a material with a discontinuity ie a crack at the surface.

When a eddy current probe is placed at the surface of a material, and eddy current is induced. I know that the eddy current will be forced under the discontinuity, however I do not know how this phenomena occurs.

This isn't any sort of accademic work!!

I would appreciate any help.

Thanks for your time

Newo