Page 1 - LN

SAI INTERNTIONAL SCHOOL
Class 7
Lesson Notes
Subject- Physics
Ch- Heat and Temperature
Subtopic- Radiation
Radiation:

Radiation is a process of heat transfer from a hot body to a cold body
without the involvement of any medium.
Radiation is a mode of heat transfer that does not require any medium
for heat to flow (it can travel in vaccum).

 Heat transfer by radiation is in the form of electromagnetic waves
and energy transferred in this process is called radiant energy.
 It is the fastest mode of transfer of heat as it travels with the
speed of light.
 The amount of radiant energy absorbed by an object depends
upon the nature and the colour of the object.

 Dark colours are good absorbers of heat.
 Light colours are poor absorbers of heat.

Application of Radiation:

 During summers we feel comfortable wearing light coloured clothes as
light colour is poor absorbers of heat.