Question:
An electron (mass m ) with an initial velocity 
is in an electric field 
It’s de Broglie wavelength at time t is given by
(a)
$\frac{\lambda_{0}}{1+\frac{e E_{0}}{m} \frac{t}{v_{0}}}$
(b)
$\lambda_{0}\left(1+\frac{e E_{0} t}{m v_{0}}\right)$
(c) λ0
(d) λ0t
Solution:
The correct answer is (a) $\frac{\lambda_{0}}{1+\frac{e E_{0}}{m} \frac{t}{v_{0}}}$