## Physics: Principles with Applications (7th Edition)

The two particles, being accelerated from rest through voltages of equal magnitude, have the same kinetic energy. The proton has a larger mass than the electron and (if they have the same KE) will have the larger momentum because $p=\sqrt{2 m KE}$. The wavelength is inversely proportional to the particle’s momentum, $\lambda = \frac{h}{p}$, so the proton has the shorter wavelength.