If a body coated black at 600K surrounded by atmosphere at 300 K has cooling rate `r_(0)`, the same body at 900 K, surrounded by the same atmosphere, will have cooling rate equal to

Options

A. `16/3 r_(0)`
B. `8/16 r_(0)`
C. `16 r_(0)`
D. `4 r_(0)`

Answer

A

Explanation

Cooling rate `alpha T^(4)-T_(0)^(4)`
`r = {((900)^(4)-(300)^(4))/((600)^(4)-(300)^(4))}r_(0) = 16/3r_(0)`