## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

(a) Point a is at a higher electric potential than point b. (b) We can rank the magnitudes of the potential differences from largest to smallest: $\Delta V_{ef} \gt \Delta V_{cd} \gt \Delta V_{ab}$ (c) Surface 1 is an equipotential surface. Surface 2 is not an equipotential surface.
(a) The electric field points from positions of higher potential to positions of lower potential. Therefore, point a is at a higher electric potential than point b. (b) We can write an expression for the magnitude of the potential difference: $\Delta V = \Delta x ~E$ Note that $\Delta V$ increases as $\Delta x$ increases. We can rank the magnitudes of the potential differences from largest to smallest: $\Delta V_{ef} \gt \Delta V_{cd} \gt \Delta V_{ab}$ (c) Surface 1 is perpendicular to the electric field. Therefore, surface 1 is an equipotential surface. Surface 2 is not perpendicular to the electric field. Therefore, surface 2 is not an equipotential surface.