A very small hole in an electric furnance is used for heating metals . The hole nearly acts as a black body . The area of the hole is `200 mm^(2)`. To keep a metal at `727^@C` , heat energy flowing through this hole per sec, in joules is (`sigma= 5.67 xx 10^(-8)Wm^(-2)K^(-4)`)

Options

A. 22.68
B. 2.268
C. 1.134
D. 11.34

Answer

D

Explanation

`E = sigmaAT^(4)`
`E = 5.67 xx 10^(-8) xx 200 xx 10^(-6) xx (727 + 273)^(4)`
`E = 11.34`