A very small hole in an electric furnace is used for heating metals. The hole nearly acts as a black body. The area of the hole is 200mm^(2). To keep a metal at 727^(@)C, heat energy flowing through this hole per sec, in joules is (sigma=5.57xx10^(-8)Wm^(-2)k^(-4))

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

1.	A very small hole in an electric furnace is used for heating metals. The hole nearly acts as a black body. The area of the hole is 200mm^(2). To keep a metal at 727^(@)C, heat energy flowing through this hole per sec, in joules is (sigma=5.57xx10^(-8)Wm^(-2)k^(-4))
Answer» 22.68 2.268 1.134 11.34 Answer :D