Question

A black rectangular surface of area 'A' emits energy 'E' per second at 27 °C. If length and breadth are reduced to `1/2` of initial value and 2 temperature is raised to 327 °C then energy emitted per second becomes ______.

पर्याय

• `"E"/4`

• `4"E"`

• `(10"E")/9`

• `(16"E")/9`

Answer 1

A black rectangular surface of area 'A' emits energy 'E' per second at 27 °C. If length and breadth are reduced to `1/2` of initial value and 2 temperature is raised to 327 °C then energy emitted per second becomes 4E.

Explanation:

`"E"_2/"E"_1 =("A"_2/"A"_1)("T"_2/"T"_1)^4=((l/2xxb/2)/(lxxb))((327+273)/(27+273))^4`

=`(1/4)(600/300)^4`

∴ `"E"_2/"E"_1=1/4xx(16)`

∴`"E"_2= 4"E".....(∵"E"_1="E")`