(i) What are the characteristic features of heat energy transfer? (ii) Explain linear expansion with diagram?

(i) What are the characteristic features of heat energy transfer? (ii)

1.	(i) What are the characteristic features of heat energy transfer? (ii) Explain linear expansion with diagram?
Answer» Solution :• Heat always flows from a system of higher temperature to a system at lower temperature. . The mass of a system is not ALTERED when it is heated or cooled. • Heat gained by the cold system is equal to heat lost by the HOT system. (ii) • When a body is heated or cooled,the length of the body CHANGES due to change in its temperature. • Then the expansion is said to be on linear or longitudinal expansion. • The ratio of increase in length of the body per degree rise in temperature to its unit length is called as the coefficient of linear expansion. • It is different for different materials. Its SI unit is `K^(-1)` • The EQUATION is `(DeltaL)/(L_(0))=alpha_(L)DeltaT` `DeltaL`- Change in length (Final length - Original length) `L_(0)` - Original length (Final temperature - Initial temperature) `alpha_(L)` -Coefficient of linear expansion