For the de Broglie wavelengths of an electron and of a proton to be equal, the electron must travel
A) much faster than the proton.
B) much slower than the proton.
C) at the same speed as the proton.
D) Hold it! Speed is irrelevant; mass is what counts.

Question

Quizplus · Accepted Answer

The de Broglie wavelength formula is λ = h/p, where λ is the wavelength, h is Planck's constant, and p is the momentum of the particle. Since momentum p = mv (mass times velocity), for an electron and a proton to have the same wavelength, the electron must have a higher velocity due to its much smaller mass compared to the proton.

For the De Broglie Wavelengths of an Electron and of a Proton