00:02
Hi, this is problem number 144.
00:05
In problem number 144, we are given the wavelength for a sodium emission at 589 nanometers.
00:20
And they would like us to calculate the mass of a photon that has this wavelength.
00:31
Right, so i think i see a way to get to this answer.
00:34
We know that we can calculate energy from wavelength because that is going to be equal to planck's constant times the speed of light divided by the wavelength.
00:43
We also know a feinstein's equation that says energy is mass times the speed of light squared.
00:52
So let's go ahead and calculate the energy of this photon first of all.
00:57
So starting with planx constant, 6 .626 times 10 to the negative 34th, joules times second, and then the speed of light is also a constant.
01:14
It's 3 .0 times 10 to the 8 meters per second.
01:21
I want to divide this product by the wavelength, which is 589 nanometers.
01:30
However, right now we have a little issue in that meters, and nanometers can't cancel because they're not the same unit...