Figure shows a copper rod joined to a steel rod. The rods have equal length and 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 = 390 W m–1 °C–1 and that of steel = 46 W m–1 °C–1.



Given-


Conductivity of copper, K1 = 390 W m–1 °C–1


Steel, k2 = 46 W m–1 °C–1.


w1.png


Let


length of rods = l and Area = A


Since rods are connected in series,


so the rate of flow of heat is same ie,


Q1 = Q2


Rate of flow of heat,


Q =


=


Since for series connected rods, Q1 = Q2,


⇒ =


⇒ A K1 = A k2


⇒ T = 10.6°C


1