An electron passing accelerating difference delta phi potential flies in the air condenser flat parallel plates of length L and departs from it. At that point, when an electron enters the condenser, the latter an electric field, the intensity of which varies with time according to E = at the law (where a = const). The vector E is perpendicular to the plane of the plates. To determine the rate at which electron emission from the condenser. The charge of an electron e, m its mass.