Calculating the Power and Impact of Black Body Radiation from the Sun

AI Thread Summary
To calculate the power radiated by the sun, use the Stefan-Boltzmann law, which states that power per area (P/A) equals Stefan's constant multiplied by the temperature in Kelvin raised to the fourth power (P/A = σT^4). The sun's temperature is approximately 6000 K, and its radius is about 700,000 km. To determine how much of this power reaches Earth, calculate the Earth's cross-sectional area and divide it by the surface area of a sphere centered at the sun. Stefan's constant is 5.67x10^-8 Wm^-2K^-4. This approach will yield the total power received by Earth from the sun.
scissors
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My problem is that I have the numbers...but I don't have a formula.

"The sun's temp. is about 6000 K, it's radius 700000 km. How much power is it radiating? If there is no dissipation between here and the sun, how much of this hits the earth?"

Is this the P = c/4*U thing?
 
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scissors said:
My problem is that I have the numbers...but I don't have a formula.

"The sun's temp. is about 6000 K, it's radius 700000 km. How much power is it radiating? If there is no dissipation between here and the sun, how much of this hits the earth?"

Is this the P = c/4*U thing?
I'm not sure what equation you are referring to. You have to use the Stephan-Boltzman law for blackbody radiation:

P/A = \sigma T^4

where P/A = Power/Area, \sigma is Stephan's constant and T is the temp. in K.

Then work out the cross-sectional area of the Earth and divide that by the area of the surface of a sphere centred at the sun and intersecting the earth.

AM
 
In case you don't know - Stefan's constant is equal to 5.67x10^-8 Wm^-2K^-4
 
Ah, I see. Thanks a lot guys!
 
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