KCET2010PhysicsThermal Properties of Matter
Two slabs are of the thicknesses d₁ and d₂ . Their thermal conductivities are K ₁ and K ₂ respectively. They are in series. The free ends of the combination of these two slabs are kept at temperatures ₁ and ₂ . Assume ₁> ₂ . The temperature of their common junction is
Options
- AK ₁ ₁+ K ₂ ₂ ₁+ ₂
- BK ₁ ₁ ~d ₁+ K ₂ ₂ ~d ₂ ~K ₁ ~d ₂+ K ₂ ~d ₁
- CK ₁ ₁ ~d ₂+ K ₂ ₂ ~d ₁ ~K ₁ ~d ₂+ K ₂ ~d ₁
- DK ₁ ₁+ K ₂ ₂ ~K ₁+ K ₂
Correct answer
C. K ₁ ₁ ~d ₂+ K ₂ ₂ ~d ₁ ~K ₁ ~d ₂+ K ₂ ~d ₁
Step-by-step solution
For first slab Heat current, H ₁= K ₁ ( ₁- ) A d ₁ For second slab, Heat current, H ₂= K ₂ ( - ₂ ) A d ₂ As slabs are in series aligned H ₁ &= H ₂ & & K ₁ ( ₁- ) A d ₁ &= K ₂ ( - ₂ ) A d ₂ & &= K ₁ ₁ ~d ₂+ K ₂ ₂ ~d ₁ ~K ₂ ~d ₁+ K ₁ ~d ₂ aligned