Neutron and Electron Wavelength

[504446047]

How do you determine whether a neutron or an electron has the shorter wavelength?

[K Honeychurch 1K]

You use the de Broglie wavelength equation wavelength=h/p=h/(mv), however you need to know the velocities of the electron and neutron.
If you are referring to the question3B on the midterm, it is given that the neutron and electron have the same speed. So, since a neutron has a greater mass its wavelength will be shorter (notice that wavelength is inversely proportional to momentum (p) which is mass x velocity).

[Vasudev Tadimeti 3B]

Use the de Broglie equation lambda=h/p, and p=mv, so lambda=h/mv. The mass of a neutron is 1.67 x 10^-27 kg and the mass of an electron is 9.11 x 10^-31 kg. Substitute these numbers into the equation and you'll find that the neutron has a shorter wavelength.