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A spherical black body of radius `r` radiates power `P`, and its rate of cooling is `R` (i)`P prop r` (ii)`P prop r^(2)` (iii)`R prop r^(2)` (iv)`R prop (1)/(r)` |
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Answer» Correct Answer - D (4) `P = e sigma A (T^(4) - T_(0)^(4)) = e sigma . 4 pi r^(2) (T^(4) - T_(0)^(4))` `P prop r^(2)` `ms (dT)/(dt) = e sigma A (T^(4) - T_(0)^(4))` `(dT)/(dt) = (e sigma A (T^(4) - T_(0)^(4)))/(ms) = (e sigma 4 pi r^(2) (T_(4) - T_(0)^(4)))/(rho . (4)/(3) pi r^(3) s` Rate of cooling `R = ( = (dT)/(dt)) prop (1)/(r )` |
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