Four rods of same material with different radii r and length l are used to connect two reservoirs of

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10-1.Thermometry, Thermal Expansion and Calorimetry

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Four rods of same material with different radii $r$ and length $l$ are used to connect two reservoirs of heat at different temperatures. Which one will conduct most heat ?

A

$r =2\,\,cm, l =0.5\,\,m$

B

$r = 2\,\,cm, l = 2\,\,m$

C

$r =0.5\,\,cm, l =0.5\,\,m$

D

$r = 1\,\,cm, l = 1\,\, m$

Solution

Heat conducted by rod, $Q=\frac{K A t \Delta T}{l}$ where $A=\pi r^{2}$

$\Longrightarrow Q=a \frac{r^{2}}{l} \quad$ where $a=K t \pi \Delta T=$ constant

$Q =a \frac{(0.02)^{2}}{1 / 2}=8 \times 10^{-4} a$

Standard 11

Physics

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