  Through tunneling, or barrier penetration, small wavefunction tails can enter
a finitely shielded cylinder with a magnetic field inside. When the shielding
increases to infinity the Lorentz force goes to zero together with these tails.
However, it is shown, by considering the radial derivative of the wavefunction
on the cylinder surface, that a flux dependent force remains. This force
explains in a natural way the Aharonov-Bohm effect in the idealized case of
infinite shielding.
