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The coefficient of thermal conductivity ...


The coefficient of thermal conductivity of copper is nine times that of steel. In the composite cylindrical bar shown in Fig. what will be the temperature at the junction of copper and steel ?

A

`75^@ C `

B

`67 ^@ C `

C

`33^@ C `

D

`20^@C`

Text Solution

Verified by Experts

The correct Answer is:
A
Let the temperature of junction be ` theta `
` ((Delta Q )/(Delta t))_("copper") = ((Delta Q )/(Delta t ))_("steel")`
`K_1 A ((100- theta))/(18) = (K_2)(A theta ( theta -0))/( 6)`
`9k_2 ((100 - theta ))/(3) =k_2 theta `
` 3 theta = 900 - 9 theta l 120 = 900 , theta = 75 ^@ C `
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