Question

A box with a total surface area of 0.83 m2

and

a wall thickness of 2.72 cm is made of an insulating material. A 11.8 W electric heater

inside the box maintains the inside temperature at 7.4

◦C above the outside temperature.

Find the thermal conductivity of the insulating material.

Answer in units of W/m · ◦ C.

Answer 1

$$k=\frac{qL}{A\Delta T}$$

$$k=\frac{(11.8)(0.0272)}{(0.83)(7.4)}=0.052\frac{W}{m\degree C}$$