In an experiment to determine the thermal conductivity of an insulating material, a thick layer of same is provided over a long copper tube inside which is, a current carrying conductor. The...

In an experiment to determine the thermal conductivity of an insulating material, a thick layer of same is provided over a long copper tube inside which is, a current carrying conductor. The temperature at two points A and B inside the insulation layer at radial distances of 2 cm and 6 cm from the centre of the tube are measured as 115°C and 42°C respectively. If the current flowing through the electric conductor is 10 A and its resistance is 2 Ω/m, determine the thermal conductivity of the insulating material. Neglect the heat loss from the end faces.