Two long parallel surfaces, each of emissivity 0.7, are maintained at different temperatures and accordingly have radiation exchange between them. It is desired to reduce 75% of this radiant heat transfer by inserting thin parallel shields of equal emissivity (0.7) on both sides. What would be the number of shields?

Two long parallel surfaces, each of emissivity 0.7, are maintained at

1.	Two long parallel surfaces, each of emissivity 0.7, are maintained at different temperatures and accordingly have radiation exchange between them. It is desired to reduce 75% of this radiant heat transfer by inserting thin parallel shields of equal emissivity (0.7) on both sides. What would be the number of shields?
A.	1
B.	2
C.	3
D.	4
Answer» C. 3

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