Question

A black rectangular surface of area A emits energy E per second at `27^circC`. If length and breadth are reduced to one third of initial value and temperature is raised to `327^circC`, then energy emitted per second becomes
A. `(4E)/(9)`
B. `(7E)/(9)`
C. `(10E)/(9)`
D. `(16E)/(9)`

Answer 1

Correct Answer - D
`T_(1)=27+273=300K,L_(2)=(1)/(3)L_(1)`
`T_(2)=273+32=600K`
`(E_(2))/(E_(1))=(A_(2))/(A_(1))((T_(2))/(T_(1)))^(4)`
`=(L_(2)b_(2))/(L_(1)b_(1))xx((600)/(300))^(4)`
`=(1)/(3)xx(1)/(3)=16`
`E_(2)=(16)/(9)E_(1)`.