The net heat interchange between non-black bodies at temperature T 1 a

1.	The net heat interchange between non-black bodies at temperature T ₁ and T₂is given by
A.	f <sub>12 </sub>F<sub> 12</sub> (T<sub> 1</sub><sup>4</sup> T <sub>2</sub><sup>4</sup>)
B.	f <sub>12 </sub>F<sub> 12</sub> A <sub>1 </sub> (T<sub> 1</sub><sup>4</sup> T <sub>2</sub><sup>4</sup>)
C.	f <sub>12</sub> A <sub>1 </sub> (T<sub> 1</sub><sup>4</sup> T <sub>2</sub><sup>4</sup>)
D.	<sub> </sub>F<sub> 12</sub> A <sub>1 </sub> (T<sub> 1</sub><sup>4</sup> T <sub>2</sub><sup>4</sup>)
Answer» C. f <sub>12</sub> A <sub>1 </sub> (T<sub> 1</sub><sup>4</sup> T <sub>2</sub><sup>4</sup>)

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The net heat interchange between non-black bodies at temperature T 1 and T 2 is given by

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The net heat interchange between non-black bodies at temperature T ₁ and T₂is given by