The ends of a metre stick are maintained at `100^(@)C` and `0^(@)C` . One end of a rod is maintained at `25^(@)C` . Where should its other end be touched on the metre stick so that there is no heat current in the rod in steady state?

Explanation

If there is no heat current in lower rod, for this temperature of point `C` should be `25^(@)C`
`i= (100 - theta_(C ))/(R_(1)) = (theta_(C ) - 0)/(R_(2))`
`(100 - 25)/(x//KA) = (25 - 0)/((1 - x) // KA`
`75 (1 - x) = 25 x`
`3 - 3x = x`
`x = (3)/(4) m = 0.75 m`