Power of Sun: Calculating Total Radiated Power

[notsam]

Homework Statement

[a] find the toal power radiated into space by the sun, assuming it to be a perfect emitter at T=5500 K. The Sun's radius is 7.0x10^8 m. From this determine the power per unit area arriving at the earth, 1.5x10^11 m away.

The Attempt at a Solution

Hey guys! Sorry for tricking you on that other problem about pressure this is the real one! :) Ok I know that a perfect emitter can be described as E=1-Tc/Th, I also know that Power= W/ T where "w' is work and 'T' is tempurature...as far as getting started though I'm completely lost.

 

[NuclearNut]

Try using the equation

(rate of thermal radiation) = sigma x e x A x (T1^4-T2^4)

here sigma is the stefan-boltzman constant, e is the emissivity so for a perfect emmiter e=1, A is the area of the surface and T1 and T2 are the temperatures (in kelvin) of the surface and evironment respectively.

You should find this gives you the correct answer as the power radiated is energy radiated per unit time, which is just the rate of thermal radiation.

Hope this helps