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rnjscksdyd
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Homework Statement
Venus and Earth may be regarded as behaving as black bodies. The mean temperature at the surface of Venus is about 600K and at the surface of Earth is about 300K. Which of the following is the best estimate for the ratio
[tex]\frac{power.radiated.per.unit.area.on.Earth}{power.radiated.per.unit.area.on.Venus}[/tex]
(A) 1/2
(B) 1/4
(C) 1/8
(D) 1/16
I had to put dots in between words.. It won't let me space them
Homework Equations
[tex]σAT^4[/tex]
The Attempt at a Solution
Venus: [tex]σAT^4 = σA(600)^4[/tex]
Earth: [tex]σAT^4 = σA(300)^4[/tex]
The actual answer is (D)
and I got this by
[tex]\frac{σA(300)^4}{σA(600)^4}=1/16[/tex]
If the above working is right, I want to know where 'A' or 'Area' disappeared to. I thought Area of Earth and Venus are different so they can't cancel out? Or is power radiated always referring to the unit surface area, or 1m^2 ?
p.s. sorry for asking too many questions, my exam is next week :(
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