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A spherical black body of radius r radia...

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)`

A

`P propr`

B

`Ppropr^(2)`

C

`R prop r^(2)`

D

`R prop (1//4)`

Text Solution

Verified by Experts

`P=(4pir^(2))(sigma T^(4))=ms(-(dT)/(dt))=-4/3 pi r^(3) p s . (dT)/(dt)`
Here `R=(dT)/(dt)`
`:.P prop r^(2)` and `R prop 1/r `
Hence B and D are correct.
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