Answer
The electron has a greater de Broglie wavelength than the proton.
Work Step by Step
We can use Equation (38-20) to find an expression for the de Broglie wavelength:
$K = \frac{h^2}{2m \lambda^2}$
$\lambda^2 = \frac{h^2}{2m~K}$
$\lambda = \sqrt{\frac{h^2}{2m~K}}$
It is given that the kinetic energy is the same for both particles.
Since an electron has a smaller mass than a proton, the electron has a greater de Broglie wavelength than the proton.
