Halliday, Resnick & Walker — Magnetic Fields: Problem 64

64 In Fig. 28-42, an electron with an initial kinetic energy of 5.0 keV enters region 1 at time \( t = 0 \). That region contains a uniform magnetic field directed into the page, with magnitude 0.010 T. The electron goes through a half-circle and then exits region 1, headed toward region 2 across a gap of 25.0 cm. There is an electric potential difference \( \Delta V = 2000 \text{ V} \) across the gap, with a polarity such that the electron’s speed increases uniformly as it traverses the gap. Region 2 contains a uniform magnetic field directed out of the page, with magnitude 0.020 T. The electron goes through a half-circle and then leaves region 2. At what time \( t \) does it leave?