Halliday, Resnick & Walker — Magnetic Fields: Problem 31

31 In Fig. 28-34, an electron accelerated from rest through potential difference \(V_1 = 2.50\text{ kV}\) enters the gap between two parallel plates having separation \(d = 16.0\text{ mm}\) and potential difference \(V_2 = 100\text{ V}\). The lower plate is at the lower potential. Neglect fringing and assume that the electron’s velocity vector is perpendicular to the electric field vector between the plates. (a) In unit-vector notation, what uniform magnetic field allows the electron to travel in a straight line in the gap? (b) If the potential difference is increased slightly, in what direction does the electron veer from straight-line motion?