Halliday, Resnick & Walker — Gauss' Law: Problem 2

2 In Fig. 23-22a, an electron is shot directly away from a uniformly charged plastic sheet, at speed \(v_s = 1.6 \times 10^5 \text{ m/s}\). The sheet is nonconducting, flat, and very large. Figure 23-22b gives the electron’s vertical velocity component \(v\) versus time \(t\) until the return to the launch point. What is the sheet’s surface charge density?