e , work done (by
the external force) per unit positive
test charge in bringing it from
infinity to the point is negative This
is equivalent to saying that work
done by the electrostatic force in
bringing the unit positive charge
form infinity to the point P is
positive [This is as it should be,
since for Q < 0, the force on a unit
positive test charge is attractive, so
that the electrostatic force and the
displacement (from infinity to P) are
in the same direction