Question

The graph shown gives the temperature along an x axis that extends directly through a wall consisting of three layers A, B and C. The air temperature on one side of the wall differ from that on the other side. Thermal conduction through the wall is steady. Out of the three layers A, B and C, thermal conductivity is great­est of layer

• A. A
• B. B
• C. C
• D. None, all have same.

Answer 1

Answer: (A)

A

Answer 2

$\frac { d \theta } { d t } = \frac { K _ { 1 } A \left( T _ { 1 } - T _ { 2 } \right) } { L _ { 1 } } = \frac { K _ { 2 } A \left( T _ { 2 } - T _ { 3 } \right) } { L _ { 2 } } = \frac { K _ { 3 } A \left( T _ { 3 } - T _ { 4 } \right) } { L _ { 3 } }$

Thus =4

Similarly $\frac { \mathrm { K } _ { 2 } } { \mathrm {~K} _ { 2 } }$= 4

thus K₁ > K₂ > K₃