STD VIII – HEAT TRANSFER (Online)

Heat

What happens, when you hold your hands on the top of a burning candle? You sense some warmth, right?! The form of energy that causes the perception of coldness and hotness is known as heat. Heat energy flows from a higher temperature body to a lower temperature body. The amount of heat per unit mass needed to raise the temperature by one degree celsius is known as specific heat.

In this topic, you will learn about heat, specific heat, measurement of heat, conduction and convection and much more

Evaporation

It takes place at all temperatures.   

It is a slow and gradual process.        

It takes place only at the surface of the liquid.            

It causes cooling.     

Vaporisation

It takes place only at a fixed temperature which is the boiling point  of the liquid.

It is a rapid and violent process.

It takes place over the entire liquid.

It does not produce cooling.

Expansion

Thermal expansion, the general increase in the volume of a material as its temperature is increased.