Gamow first solved the one-dimensional case of quantum tunneling using the WKB approximation. Considering a wave function of a particle of mass m, we take area 1 to be where a wave is emitted, area 2 the potential barrier which has height V and width l (at 0 < x < l ), and area 3 its other side, where the wave is arriving, partly transmitted and partly reflected. For a wave number k and energy E we get: