Question

Describe various effects of heat on matter.

Answer 1

1. When a hot body and cold body are brought in contact with each other, energy flows between them.
2. The energy flows from the hot body to the cold body.
3. The energy which is transferred is heat energy or simply heat.
4. The SI unit of heat is Joule. Its symbol is J.
5. The effects created by heat on the matter are:
   1. Changes in temperature.
      -The temperature of a body increases when it gains heat and decreases when it loses heat.
   2. Changes in size.
      -The size of a body increases when subjected to heating. It is called thermal expansion. The degree of expansion depends on the nature of the substance.
   3. Changes in the state.
      -Heat causes the substance to change its state. For example, ice(solid) changes to water (liquid )on heating. On further heating, water changes to vapor.
   4. Chemical change.
      - Sometimes, heating the substances cause them to change, resulting in the formation of new substances. For example, burning a piece of paper forms new substances ash and carbon dioxide.

Thus, heat cause change in temperature, change in size, change in state, and may result in some chemical changes.