An electron (mass m) with an initial velocity $\overrightarrow{v} =v_0 \hat i$ is in an electric field $\overrightarrow{E} = E_0 \hat j$. If $\lambda_0 = \large\frac{h}{mv_0}$ , Its de-Broglie wave length at time t is given by

Question

$\begin{array}{1 1} \lambda_0 \\ \lambda_0 \sqrt{1+ \large\frac{e^2 E_0 t^2}{m^2 V_0 ^2}} \\ \large\frac{\lambda_0}{\sqrt{ 1+\large\frac{e^2 E_0^2 t^2}{m^2v_0^2}}} \\ \large\frac{\lambda_0}{ 1+\large\frac{e^2 E_0^2 t^2}{m^2v_0^2}} \end{array}$