A box ,total surface area 2.20m² and a wall thickness 6cm is made of an insulating material.10 W electric heater inside the box maintains the inside temperature at 20°C above the outside temperature. thermal conductivity of the insulating material?
Thermal conductivity can be thought of as a the flux of heat (energy per unit area per unit time) divided by the temperature gradient(temperature difference per unit length).
The expression is:
Putting in the values: