A metal rod of length 2 m has cross sectional areas 2A and A as shown in figure. ends are maintained

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10-2.Transmission of Heat

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$A$ metal rod of length $2$$m$ has cross sectional areas $2A$ and $A$ as shown in figure. The ends are maintained at temperatures $100°C$ and $70°C$ . The temperature at middle point $C$ is...... $^oC$

A

$80$

B

$85$

C

$90$

D

$95$

Solution

(c) Let $\theta$ be temperature middle point $C$ and in series rate of heat flow is same

==> $K(2A)(100 – \theta ) = KA(\theta – 70)$

==> $200 – 2\theta = \theta – 70$

==> $3\theta = 270$==> $\theta = 90^\circ C$

Standard 11

Physics

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