## Question

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

### Solution

If the ends of the rods are maintained at temperatures and , the rate of flow of heat through each rod is given by

And

Where *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 2*A*. If *k* is the thermal conductivity of the composite rod, the rate of heat flow is

But Therefore

or **).**

#### SIMILAR QUESTIONS

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