00:01
Calculate the wavelength in nanometers of a photon emitted by a hydrogen atom when electron drops from the n equals 5 state to the n equals 3 state.
00:14
So we're going to use the equation for restart.
00:20
So we're going to use the equation for the change in energy is equal to k times 1 over n sub 1 squared minus 1 over n sub 2 squared.
00:34
And then this is going to equal hc over lambda.
00:38
We don't need to know the energy.
00:41
We are looking for lambda.
00:42
H is our planks constant, and that is 6 .626 times 10 to the minus 34.
00:49
And c is the speed of light at 2 .998 times 10 to the 8.
00:56
And we have meters per second.
00:59
Now, h is going to be joules per second, and k.
01:06
Well, that's going to have 2 .179 times 10 to the minus 18 joules.
01:13
So we will write 2 .179 times 10 to the minus 18 times 1 over 5 squared minus 1 over 3 squared.
01:26
That's equal to 6 .626 times 10 to the minus 34 times 2 .998 times 10 to the 8th.
01:37
All over lambda.
01:41
So let's start with the fractions in the parentheses.
01:44
We're going to have one divided by five squared, which is 25 minus one over nine or three squared...