Understand the de Broglie wavelength formula.

Step 1: Understand the de Broglie wavelength formula.
The de Broglie wavelength $\lambda$ of a particle is given by:

$$\lambda = \frac{h}{p}$$

where $h$ is Planck's constant and $p$ is the momentum of the particle.

Step 2: Relate momentum to acceleration by an electric field.
If a charged particle with charge $q$ and mass $m$ is accelerated from rest by a constant electric field $E$ for a time $t$, its acceleration $a$ is given by Newton's second law:

$$F = qE = ma$$ $$a = \frac{qE}{m}$$

The velocity $v$ after time $t$ is:

$$$$