Questions

Two rods A and B of different materials are welded together as shown in Fig. If their thermal conductivities are k_{1} and k_{2}, the thermal conductivity of the composite rod will be

Get a detailed solution and exclusive access to our masterclass to ensure you never miss a concept

By Expert Faculty of Sri Chaitanya

a

2k1+k2

b

32k1+k2

c

k1+k2

d

12k1+k2

NEW

detailed solution

Correct option is D

If the ends of the rods are maintained at temperatures θ1 and θ2 the rate of flow of heat through each rod is given by Q1=k1Aθ1−θ2dQ2=k2Aθ1−θ2dwhere A is the cross-sectional area of each rod and d is the length of each rod. Now the cross-sectional area of the composite rod is 2A. If k is the thermal conductivity of the composite rod, the rate of heat flow is Q=k(2A)θ1−θ2dBut Q=Q1+Q2. Therefore k(2A)θ1−θ2d=k1Aθ1−θ2d+k2Aθ1−θ2dor k=12k1+k2Hence the correct choice is (d).

Similar Questions

Two rods of equal length and diameter have thermal conductivities 3 and 4 units respectively. If they are joined in series, the thermal conductivity of the combination would be:

Get your all doubts cleared from

Sri Chaitanya experts

+91

799 666 8865

support@infinitylearn.com

6th Floor, NCC Building, Durgamma Cheruvu Road, Vittal Rao Nagar, HITEC City, Hyderabad, Telangana 500081.

JEE

JEE Mock Tests

JEE study guide

JEE Revision Notes

JEE Important Questions

JEE Sample Papers

JEE Previous Year's Papers

NEET

NEET previous year’s papers

NEET important questions

NEET sample papers

NEET revision notes

NEET study guide

NEET mock tests

Popular Books

HC Verma Part 1HC Verma Part 2RS AgarwalRD SharmaLakhmir SinghDK GoelSandeep GargTS GrewalNCERT solutions

Class 12 NCERT SolutionsClass 11 NCERT SolutionsClass 10 NCERT SolutionsClass 9 NCERT SolutionsClass 8 NCERT SolutionsClass 7 NCERT SolutionsClass 6 NCERT Solutions