Absorption and Radiation of Heat


1. All objects can absorb and give out (radiate) heat. But some objects absorb give out heat better than others.


2. The ability of an object to absorb and give out heat depends on the type and colour of its surface (dull or shiny and light-coloured or dark-coloured).


3. The rate at which heat is absorbed and given out also depends on the surrounding temperature of the object.


Some application of absorption and release of heat in daily life

1. Most of the buldings and houses are painted with white or brightly coloured paint so that less heat is absorbed and the interior can be kept cool. White and bright surfaces are good reflectors of heat and poor absorbers of heat.


2. The oil tank of an oil tanker is painted silver so that it becomes a good reflector of heat. This is much safer as less heat will be absorbed by the petrol inside the tank. Oil storage tanks are also painted with shiny aluminium paint to reflect the radiated heat away so as to keep the contents (oil) cool.


3. The base of a heating utensil or a pot is usually dull and black. This makes it a good absorber of heat.