Problem 3.378

A proton accelerated by a potential difference $V=500 \mathrm{kV}$ flies through a uniform transverse magnetic field with induction $B=0.51$ T. The field occupies a region of space $d=10 \mathrm{~cm}$ in thickness (Fig. 3.99). Find the angle $\alpha$ through which the proton deviates from the initial direction of its motion.