We know that Heat from the sun warms the Earth and Heat is produced when things burn. Heat and light from the Sun support life on the earth. To understand what heat is, we must first learn about thermal energy.
Matter is made up of extremely small particles called molecules. For example the air water and a piece of metal are all made up of certain types of molecules.
The molecules that form water, air and the metal are different from each other. But they have one common feature. They all show a movement.
The molecules of a substance move because they possess energy. The sum of the energy possessed by all the moving molecules of the substance is called its Thermal energy.
Everything around us has some thermal energy. The molecules of ice have some motion, which is why even a cold object has some thermal energy.
While thermal energy refers to the total energy possessed by a substance, temperature tells how hot or cold substance is. It is also the Measure of how fast or slow the molecules are moving.
Temperature of a substance can be measured using a device called thermometer.
What is Heat ?
Heat is the thermal energy that flows. Thermal energy flows between objects due to a difference in temperature. Heat transfer occurs from a region of higher temperature to a region of lower temperature. That is why heat flows from one object to another only when one object is warmer than the other.
The flow of thermal energy can be compared with the flow of water. Water always flows from a higher level to a lower level. Shimla thermal energy always flows from a region of a higher temperature to a region of lower temperature. The flow of thermal energy will continue until the temperature of the two objects become equal. Electoral Politics
How is heat transferred
The main ways by which transfer of heat occurs is conduction convection and radiation.
Conduction occurs when two objects at different temperatures are in contact with each other.
Conduction is the mode of heat transfer when a hotter object comes in contact with the colder object. Heat spreads throughout the object until both the objects reach the same temperature.
Convection is the transfer of heat through a fluid from a region aap highest temperature to a reason of lower temperature by the movement of the fluids itself.
When a liquid or a gas is heated, it expands. As a result, it becomes lighter and move upwards. The cooler heavier fluid from the surrounding resources to take its place and is heated inturn. This process continues and gives rise to a convection current through which heat energy flows and the entire liquid or gas gets heated.
Unlike conduction and convection, radiation is a method of heat transfer that does not need contact between a water object and a cooler object. For example you can feel the heat of the sun even when you are indoors. Similarly we can feel the heat of fire from a distance. Heat can be transferred through and impetus space by radiation.
Thermal energy is the total internal energy contained in a matter while temperature tells us how hot or cold the matter is. Heat energy is thermal energy that flows. Heat always flows from a region of higher temperature to a region of lower temperature. Conduction is a process in which heat is transferred from a region of higher temperature to a region of lower temperature through vibrating molecules.
Metals are good conductors of heat. Material like wood and plastic which are poor conductors of heat are good heat insulators. Convection is the flow of heat through a fluid from a region of higher temperature to a region of lower temperature by the movement of the molecules.