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A wall has two layers A and B, each made of defferent material. A has thickness 10 cm, while B has thickness 20 cm, their coefficients of conductivities are in the ratio of 3:1. A constant temperature difference of 35^(@)C exists across the wall. The difference of temperature across the layer A is : |
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Answer» `28^(@)C`  In STEADY state `H_(1)=H_(2)`. `(k_(1)A(DeltaT_(1)))/(l_(1))=(k_(2)A(DeltaT_(2)))/(l_(2))` `(3kDeltaT_(1))/(10)=(kDeltaT_(2))/(20)` `(DeltaT_(1))/(DeltaT_(2))=1/6""rArr""DeltaT_(2)=6DeltaT_(1)` Also `DeltaT_(1)+DeltaT_(2)=35` `DeltaT_(2)=6DeltaT_(1)=35""rArr""DeltaT_(1)=5^(@)C`. Thus correct choice is (c ). |
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