Two rods one made of copper and other made of steel of the same length and same cross sectional area are joined together. The thermal conductivity of copper and steel are $385\,J\,s ^{-1}\,K ^{-1}\,m ^{-1}$ and $50\,J\,s ^{-1}\,K ^{-1}\,m ^{-1}$ respectively. The free ends of copper and steel are held at $100^{\circ}\,C$ and $0^{\circ}\,C$ respectively. The temperature at the junction is, nearly $.......^{\circ}\,C$

One end of a thermally insulated rod is kept at a temperature $T_1$ and the other at $T_2$ . The rod is composed of two sections of length $l_1$ and $l_2$ and thermal conductivities $K_1$ and $K_2$ respectively. The temperature at the interface of the two section is

Three rods of equal length and cross sectional area and coefficient of thermal conductivities $K, 2K$ and $3K$ are joined as shown in figure temperature of their ends are $110\ ^oC, 20\ ^oC$ and $0\ ^oC$ respectively then temperature of junction will be ......... $^oC$

A body of length 1m having cross sectional area $0.75\;m^2$ has heat flow through it at the rate of $ 6000\; Joule/sec$ . Then find the temperature difference if $K = 200\;J{m^{ - 1}}{K^{ - 1}}$ ...... $^oC$

Two rods $A$ and $B$ of different materials are welded together as shown in  figure.Their thermal conductivities are $K_1$ and $K_2$  The thermal conductivity of the composite rod will be

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