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))

A very small hole in an electric furnance is used for heating metals .

1.	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))
Answer» 22.68 2.268 1.135 11.34 Answer :D