An electron (mass m) with an initial velocity $\overrightarrow{v} =v_0 \hat i (v_0 > 0)$ is in an electric field $\overrightarrow{E} =- E_0 \hat i (E_0= constant >0)$ . Its de-Broglie wave length at time t is given by

Question

$\begin{array}{1 1}\large\frac{\lambda_0}{(1+ \frac{e E_0}{m}. \frac{t}{v_0})} \\ \lambda_0 (1+\large\frac{e E_0 t}{mv_0}) \\ \lambda_0 \\ \lambda_0 t \end{array}$