Question

A slab of a thermal insulator is 100 cm2 in cross section and 2 cm thick. Its thermal conductivity is 0.1 J/s.m.ºC. If the temperature difference between opposite faces is 100 ºC, how much heat flows through the slab in one day?

Answer 1

-5 W is the heat flows through the slab in one day

Explanation:

• The heat transferred is directly proportional to the area of the material and the temperature differences in the body, whereas the heat transfer is inversely proportional to the length of the material
• The equation can be written as  $Q=-k \frac{ A T}{l}$ where Q is the heat transfer, k is the thermal conductivity of the material, A is the area of the material and T is the difference in the temperature and the l is  the length of the material.
• Given that, A= 100 $cm^{2}$ , l= 2 cm, k = 0.1 J/S. m. c and T= 100 degree Celsius
• Substitute these values in the equation, you will get Q= -5 W