What is the temperature of the steel -copper junction in the steady state of the system shown in the figure. Length of the steel rod `=25cm`, length of the copper rod `=50cm`, temperature of the furance `=300^(@)C`, temperature of the other end `=0^(@)C`. The area of cross section of the steel rod is twice that of the copper rod. (Thermal conductivity of steel `=50Js^(-1)m^(-1)K^(-1)` and of copper `=400 J s^(-1)m^(-1)K^(-1)`)

Explanation

Let temperature be `T`, in steady state series connection heat transferred `((DeltaQ)/(Deltat))` through each rod is same.
`(DeltaQ)/(Deltat)=(k_(1)A_(1)(T_(1)-T))/(L_(1))=(k_(2)A_(2)(T-T_(2)))/(L_(2))`
`300-T=((L_(1))/(L_(2)))=((k_(2))/(k_(1)))((A_(2))/(A_(1)))(T-0)`
`300-T=2T`
`T=100^(@)C`