question_answer

Match List-I (Surfaces with Orientations) with List-II (Equivalent Emissivity) and select the correct answer using the codes given below the lists:

List I (Surfaces with orientations)		List-II (Equivalent Emissivity)
A.	Infinite parallel planes	1.	\[{{\in }_{1}}\]
B.	Body 1 completely enclosed by body 2 but body 1 is very small	2.	\[\frac{1}{\frac{1}{{{\in }_{1}}}+\frac{1}{{{\in }_{2}}}-1}\]
C.	Radiation exchange between two small gray bodies	3.	\[\frac{1}{\frac{1}{{{\in }_{1}}}+\left( \frac{{{A}_{1}}}{{{A}_{2}}} \right)\left( \frac{1}{{{\in }_{2}}}-1 \right)}\]
D.	Two concentric cylinders with large lengths	4.	\[{{\in }_{1}}.{{\in }_{2}}\]

Codes:

A) A\[\to \]3, B\[\to \]1, C\[\to \]4, D\[\to \]2

B) A\[\to \]2, B\[\to \]4, C\[\to \]1, D\[\to \]3

C) A\[\to \]2, B\[\to \]1, C\[\to \]4, D\[\to \]3

D) A\[\to \]3, B\[\to \]4, C\[\to \]1, D\[\to \]2