We all know that the sun gives us light. Does
it give us heat? After standing under the sun light for some time, touch your
head. Does it feel hot? Yes, it feels hot because the sun gives out heat
besides light. Now, You can understand why it is difficult to walk bare-footed
on sunny days in the afternoon.
* Combustion (Burning)
Heat energy can be generated by the burning of
fuels like wood, kerosene, coal, charcoal, gasoline/petrol, oil, etc., In your
home, how do you get heat energy to cook food?
Rub your palms for some time and then hold them
to your cheeks. How do you feel?
We can generate heat by rubbing two surfaces of some substances. In the past
people used to rub two stones together to light fire.
electric current flows through a conductor, heat energy is produced. The water heater,
iron box, electric kettle etc., work on this principle.