Work Step by Step
In Figure 21.28a, a charge that is released will feel a force tangent to the electric field line and accelerate in that direction. All of the field lines are straight lines. The charge starts out with a velocity directed along one line and keeps feeling a force along the same field line, so it will continue to move along the same field line, faster and faster. In Figure 21.28b, the field lines are curved (except for the those on the horizontal line connecting the 2 charges). A charge that is released will feel a force tangent to the electric field line that it starts on and accelerate in that direction. However, because the field line isn’t straight, the charge’s velocity will soon carry it off that initial field line.