Two metal cubes A and B of same size are arranged as shown in Figure. The extreme ends of the combination are maintained at the indicated temperatures. The arrangement is thermally insulated. The coefficients of thermal conductivity of A and B are `300W//m ^@C and 200 W//m^@C,` respectively. After steady state is reached the temperature t of the interface will be ......

Explanation

The heat temperature though `A` per second
`Q_(1)=K_(1)A(100-t)//l`
The heat transferred through `B` per second
`Q_(2)=K_(2)A(t-0)//l`
At steady state, `K_(1)A(100-t)//l=K_(2)A(t-0)//l`
`implies 300(100-t)=200(t-0)`
`implies 300-3t=2t implies t=60^(@)C`