Chapter 5, Problem 32R

To determine

To identify the material which is a poor thermal insulator.

Explanation of Solution

Introduction:

Thermal insulators are those substances which do not allow heat to escape or pass through them.

Thermal conductors are the substances or materials which let thermal energy to conduct through them or pass through them. Metals are the best conductors of thermal energy as they allow the maximum amount of heat energy to pass through them. Metals have free and loosely bound electrons which help in thermal and electrical conductivity. On the other hand, non- metals and some other materials like wood, plastic, feathers, etc. are poor conductors of heat as they do not have free and loosely bound electrons in them to transfer and conduct heat. So poor thermal insulators refer here to those materials which are not insulators but are conductors. Out of iron, feathers, air and plastics, a poor thermal insulator is iron.

Conclusion:

Hence, out of the four iron, feathers, air and plastics, a poor thermal insulator is iron.