Unit 11:  Heat and temperature                                    1   2   3   4   5   6

6. Conductors and insulators

Thermal conductivity  is the capability of substances to conduct heat.

We can differentiate between thermal conductors and thermal insulators.

- Thermal conductors  transmit thermal energy quickly from one point to another: for example, silver, copper, aluminium and all other metals.

   - Thermal insulators transmit thermal energy slowly from one point to another:

      for example, porous or fibrous substances that have air inside, such as brick,

      wood or cork.

6.1. Classify the following substances as thermal insulators or thermal conductors: copper, glass, water, steel, wood, brass, aluminium, iron, cork, plastic, porexpan, tin, air, silver.

6.2. Thermos flasks are containers used to store liquids that we want

        to keep at the same temperature for many hours. The container is

        a hermetic bottle which structure is shown in the picture.

        Explain how the thermos flask prevents heat’s loss by conduction,

        convection and radiation.