If k be the kinetic energy and m the mass of a moving particle then the de-Broglie wavelength of the particle is :

$λ = \frac{h}{\sqrt{mk}}$ $λ = \frac{2h}{\sqrt{mk}}$ $λ = \frac{h}{2\sqrt{mk}}$ $λ = \frac{h}{\sqrt{2mk}}$

$λ = \frac{h}{\sqrt{2mk}}$

$\lambda = \frac{h}{p} = \frac{h}{\sqrt {2mk}}$