Solving a problem in physics section 71 point 44 electr

44. An electron with a certain initial velocity υ0 flies into a plane horizontal capacitor parallel to the plates at an equal distance from them. The potential difference between the plates of the capacitor U = 300 V; the distance between the plates d = 2 cm; the length of the capacitor is l = 10 cm. What should be the limiting initial velocity υ0 of the electron so that the electron does not fly out of the capacitor? Solve the same problem for an α-particle.