An electron (mass m) with initial velocity $\overrightarrow v = {v_0}\widehat i + {v_0}\widehat j$ is in an electric field $\overrightarrow E = - {E_0}\widehat k$. If $\lambda _0$ is initial de-Broglie wavelength of electron,
its de-Broglie wave length at time t is given
by :
${{{\lambda _0} } \over {\sqrt {1 + {{{e^2}{E^2}{t^2}} \over {{m^2}v_0^2}}} }}$
${{{\lambda _0}\sqrt 2 } \over {\sqrt {1 + {{{e^2}{E^2}{t^2}} \over {{m^2}v_0^2}}} }}$
${{{\lambda _0} } \over {\sqrt {1 + {{{e^2}{E^2}{t^2}} \over {2{m^2}v_0^2}}} }}$
${{{\lambda _0}} \over {\sqrt {2 + {{{e^2}{E^2}{t^2}} \over {{m^2}v_0^2}}} }}$
