00:01
Okay, in this problem we have a non -relativistic particle with mass.
00:05
We are asked to find the wavelength of this particle in terms of its mass and its kinetic energy.
00:10
And once we have this expression, we're asked to find specifically the wavelength of an electron with 800 ev of kinetic energy.
00:17
The equations we'll use is the definition of a de burglier wavelength in terms of h in momentum, length constant h.
00:24
We also need the simple definitions for kinetic energy and momentum.
00:28
All right, let's jump into it.
00:30
So starting off with our definition of the debroglié wavelength, h over p, we're going to replace the momentum with something involving m and k.
00:39
To do that, we will look at our definitions for k and p, and we'll combine them to get k equals p squared over 2m.
00:53
We can do this by replacing v, by solving for v in one of these cases, the velocity, and then combining it with the other equation.
01:01
We end up with this new expression for kinetic energy in terms of momentum.
01:04
And in one more step, we can then express p, momentum, in terms of connect energy and mass, p is equal to 2mk.
01:13
So we can take this momentum, plug it into our definition for debruglia wavelength...