일반물리학 2 — Electric Potential: Problem 43

43 An infinite nonconducting sheet with a uniform surface charge density $\sigma$ sets up parallel equipotential surfaces. Any pair of surfaces differing by 25.0 V are separated by 8.80 mm. (a) What is the magnitude of the surface charge density? (b) If an electron is released near the sheet, does it tend to move from higher to lower potential or vice versa?