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* Evaporation occurs at all temperature while boiling occurs at the boiling point of the liquid.

* Evaporation causes cooling while boiling does not cause cooling.

* Evaporation occurs only at the surface while boiling occurs in every part of the liquid.

* Wind assists evaporation while boiling wind has no effect on boiling.

What is Expansion?


Expansion occurs mostly in solid,liquid and gas when heated. Most solid and liquid expand and contract when cooled.

What is Expansion In Solids?

Solids expand when heated and contract when cooled.

This can be demonstrated by the following experiment Ball and Ring experiment.

What is Linear Expansion?

Different solids expand by different amount when heated over the same temperature. This is because they have linear expansivity.

The linear expansivity of a substance is defined as the increase in length per length degree rise in temperature. It is measured in k-

What is Heat Energy?

Heat energy is the transfer of heat from one body to another. Heat energy flows from a body at a higher temperature to another at a low temperature. Transfer of heat can be done by Conduction, Convection and Radiation.

Conduction is the process by which heat energy is transferred through a material, the average position of the particles of the material remaining the same.

It is our everyday experience that when we pour hot water into an aluminum cup,the handle of the cup outside would be hot to handle. Most metals allow heat energy to pass through them very easily, such materials are known as good conductors of heat. Non metals are poor conductors of heat or insulators such materials do not allow heat to pass through them easily.

The ability of a metal to conduct heat is known as its thermal conductivity through most metals are good conductors, their thermal conductivities differ from metal to metal.

Kinetic Molecular Theory Explanation Of Conduction

When one end of a material is heated, the materials there gain energy and vibrate with increasing speed they vibrate faster and faster and farther rout. They therefore bump against neighboring molecules more than before and so transfer greater energy to them. thus goes on all the way along the solid.

All the molecules of the solid eventually vibrate note rapidly about their fixed positions. Therefore in this way thermal energy is transferred along the solid although the average position of the molecules remain unchanged.

Convection is simply a process by which heat is transferred in a liquid or a gas by the actual movement of the heated fluid from the hotter region to the colder region.

Radiation is a process by which heat is transferred from a hotter region to a cooler region without heating the intervening medium. No materials medium is required in Radiation. Heat from the sun reaches the earth by radiation. The heat energy produced by radiation is called radiant energy.

Submitted by: Floxy

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