00:02
Okay, so we're looking at the probability distribution for the lowest hydrogen atom state.
00:12
A0 is the bore radius.
00:17
So this is the probability distribution as a function of r, and this is the probability, the actual probability you integrate small p out to radius r, to find.
00:37
The probability that the particle lies between 0 and r.
00:48
So first of all, we're going to let r go to infinity and calculate the integral, and i'll make a substitution.
01:01
Y is, yeah, 2s over a0.
01:31
Let me make that substitution.
01:35
And so we get the integral of y squared e to the minus y, d, y is 2.
01:47
When you go from zero to infinity, that whole thing's equal to 1.
01:51
Which means it's a good probability distribution because the integral over zero to infinity has to be one so it's normalized correctly the limit of r goes to zero if the probability distribution is zero and we also want to find the maximum so we take d of little p in respect to r take that derivative and we set that equal to zero so that means the factor out in front has to be zero and that 0 when r is equal to a 0 or r equals 0 well r equals 0 is not interesting so we'll cross that one out and it's r is equal to a 0 so it peaks at the bore radius we want to find out what capital p of 4 a 0 is so we have to do this integral we'll make that same substitution again should be plus 2 s and that is so to be within four bore radii we're going to have a probability of 0 .986 which is near certainty 1 .0 would be certain and here's a graph of little p if we found out before that the peak here is at a 0 when we want to find the average value of and so we integrate the probability distribution with an additional r, which is s...