A point source S of light is emitting power P.A sphere of radius r is situated at distance R from source S (R>>>r),has mass M ans specific heat capacity C.
Find the time in which temperature of sphere rises by θ°C
My answer is R2MCQ/Pr2 but answer given is 4R2MCQ/Pr2
Why ?
Where is my mistake?:-(
Please correct me
Give full answer so that I can correct my mistake :-(
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2 Answers
1hey this is straightforward .. solid angle subtended by planet at the source = A/R^2=≈πr2/R2
so fraction of energy reaching the planet = πr2/R2/4π (as 4π is the total sollid angle)
so we have energy reaching the planet in time t= (πr2/R2/4π )*P*t=MCΔT
we get t = 4MCΔTR2/Pr2
62finally i seem to be seeing someone with real good zing in physics... (am not saying this for this solution..)
Last yr it was Celestine and Rohan...
This yr there havent been too many!