40. An electron flew into a flat capacitor, being at the same distance from each plate and having a speed of 106 m / s, parallel to the plates, the distance between which is 2 cm. The length of each plate is 10 cm. What is the smallest potential difference to be applied to the plates, so that the electron does not fly out of the capacitor?

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)