The difference in electric potential energy between the two points is
where q is the magnitude of the charge and
is the electric potential difference.
But for energy conservation, the difference in electric potential energy
between the two points is equal to the work done to move the charge between A and B:
so we have
and by substituting the numbers of the problem, we find the value of:
where q is the magnitude of the charge and
But for energy conservation, the difference in electric potential energy
so we have
and by substituting the numbers of the problem, we find the value of