In the Ingen hausz method to compare the thermal conductivities of differnet substances the length upto which wax melted in copper and zinc rods are `9.3 cm` and `5cm` respectively Compare their thermal conductivities .

Explanation

Given `l_(c) = 9.3cm` and `l_(z) =5cm`
`:'(K_(c))/(K_(z)) = (l_(c)^(2))/(l_(z)^(2)) = ((9.3)/(5))^(2) =3.46`
Thus the thermal conductivity of copper is `3.46` times that of zinc .