  The back-action exerted by the moving electron on the magnetic flux in the
A-B effect is analyzed. It is emphasized that a reasonable interpretation on
the A-B effect should be consistent with the uncertain principle. If the
back-action on the magnetic flux is reduced to zero, the A-B effect should not
be observed, even through the vector potential still exists in space. To verify
this interpretation, a new experimental scheme is proposed in this paper.
