00:01
The total radiated intensity is going to be equal to sigma t4.
00:06
Sigma is our stefan boltzmann constant, which is 5 .6 times 10 to the negative 8, times 20 times 10 to the 3 to the 4th power, and we get an intensity of 1 .88 times 10 to the 10 watts per meter squared.
00:21
Now, the total peak intensity wavelength is equal to 2 .9 times 10 to the negative 3 divided by t.
00:28
So if we plug in our values, we have 2 .9 times 10 to the negative 3 divided by 24 times 10 to the 3, which gives us 1 .208 times 10 to the negative 7 meters.
00:43
So it's going to be less than the limit of visibility.
00:47
So to find the radius of series b, we can use area as equal to power divided by intensity.
00:54
We can substitute our value of 1 times 10 to the 25 divided by 1 .8 times.
01:00
10 to the 10, and we get 5 .315 times 10 to the 14.
01:05
And remember, area is equal to 4 pi r squared.
01:09
So the radius squared is area over 4 pi, and so that means a radius is a square root of area divided by 4 pi...