What is the energy density of sunlight on Earth and near the surface of the sun?

[theinfojunkie]

[SOLVED] Energy Density of Sunlight

Homework Statement

Use the solar constant (1350 W/m^2) to calculate the energy density of sunlight at a)Earth and b) near the surface of the sun.

Homework Equations

Stefan-Boltzman = (2pi^5)/(15(h^3)(c^2))
h=6.63x10^-34 j.s
L(solar luminosity)=4pi(D^2)S
S=1340 W/m^2

The Attempt at a Solution

I don't know what I'm doing. I'm assuming those are the more important things to use.
I'm getting frustrated with this and really need some help. I'm trying to plug in the power per area into the stefan boltzman eq to see if I can find the answer but it isn't working.

 

[theinfojunkie]

Thought about it some...

Could I use Planks formula or Raleight Jeanes law to solve this? Since the wavelength is rather large, I'm thinking I could, but I'm not sure how to apply it.

 

[theinfojunkie]

dR/D(lambda)=dU/d(lambda)(4/c)
du=4dR/c
integrate
u=4R/c

where R is 1350(solar constant) and gives the energy density on earth.

for part b

L=4pir^2 S(solar constant)
S=L(luminosity)/4pir(of the sun)^2
then u=4r/c where R=S