The wave nature of matter

Question

Experiments are performed with ultracold neutrons having velocities as small as 1.00m/s. What is the wavelength of sucha a neutron? What is the neutrons kinetic energy in eV?

Answer 1

Kinetic energy is mv^2/2.  The mass of a neutron is 1.67 x 10^-27 kg, velocity is given, and divide by 2, gives energy in Joules.

Energy is equal to hv/wavelength.  H is Plank's constant (6.63 x 10^-34).  Rearrange formula so wavelength = hv/Energy.

Take energy (J) / 1.6 x 10^-19 to get energy in eV.