00:01
So we want to find the strength of the external magnetic field.
00:04
So we know that the energy difference to a magnetic field, delta e, is equal to muceb b times the magnetic field b, where muza b is bores magnetron.
00:16
And the relationship between energy and wavelength, e is equal to hc over lambda.
00:20
So we can take the derivative of e, de, with respect to lambda, and this gives us hc over lambda squared.
00:29
So we just took the derivative of this with respect to lambda.
00:32
So this is hc over lambda squared d lambda.
00:40
Well, d .e is the same as delta e.
00:42
It's the same as the change in energy.
00:44
So d .e is equal to delta e.
00:46
And d lambda is equal to delta lambda.
00:48
So this is delta e is equal to hc over lambda squared delta lambda.
00:58
Well, we know delta lambda, and we know lambda.
01:01
We were given those values in the problem...