Figure shows a copper rod joined to a steel rod. The rods have equal length and and the equal cross sectional area. The free end of the copper rod is kept at `0^(@)C` and that of the steel rod is kept at `100^(@)C` . Find the temperature at the junction of the rods. conductivity of copper `=390Wm^(-1)C^(-1)` and that of steel `=46Wm^(-1)C^(-1)` .

Answer

A, C

Explanation

`H_(steel) = H_(copper)` (two rods are in series)
`:. ((TD)_S/(l//KA)_S) = ((TD)_C/(l//KA)_C)`
or `K_S (TD)_S = K_C (TD)_C`
or ` 46(100-theta) = 390 (theta-0)`
Solving we get, `theta = 10.6^@C`.