Answer
As the kinetic energy increases, the de Broglie wavelength decreases.
Work Step by Step
We can write an expression for the de Broglie wavelength:
$\lambda = \frac{h}{p}$
$\lambda = \frac{h}{\sqrt{2~m~E}}$
We can see that as the kinetic energy $E$ increases, the de Broglie wavelength decreases.
