Questions
Two rods A and B of different materials are welded together as shown in Fig. If their thermal conductivities are k1 and k2, the thermal conductivity of the composite rod will be
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
799 666 8865
support@infinitylearn.com
6th Floor, NCC Building, Durgamma Cheruvu Road, Vittal Rao Nagar, HITEC City, Hyderabad, Telangana 500081.
JEE Mock Tests
JEE study guide
JEE Revision Notes
JEE Important Questions
JEE Sample Papers
JEE Previous Year's Papers
NEET previous year’s papers
NEET important questions
NEET sample papers
NEET revision notes
NEET study guide
NEET mock tests