Heat energy definition
Heat energy is the manifestation of the energy in the form of heat. All materials have atoms that form molecules with constant movement and vibration. This movement of atoms generates a kinetic energy called heat or heat energy.
If we increase the temperature of any element, we increase its heat energy. However, when we increase the heat energy of an element it's not guarantee that its temperature is increased. The temperature is the same during the stage of changes. A good example is heating some water. Little by little we obtain heat energy and the temperature increases. However, when it reaches 100 °C (boiling temperature) the heat energy changes to another stage (gas, steam) and the temperature is maintained.
Transmission of thermal energy
Thermal energy can be transmitted from one body to another following the laws of thermodynamics in three different ways:
- Transmission of heat by radiation.
- Transmission of thermal energy by conduction.
- Heat transmission by convection.
Radiation Heat energy is transmitted through electromagnetic waves. It's how the sun transmits its heat energy. The main example of this case is found in solar thermal installations, which take advantage of solar radiation to heat water. The hot water obtained from these solar installations is usually used for heating and for use as domestic hot water.
The transfer of heat energy by conduction is produced when a hot body is contacting physically with a colder body. The energy always circulates from the hot body to the cold body. If both bodies have the same temperature no energy transfer is produced. If we touch ice we transfer heat energy from our hand to the ice, feeling a cold sensation.
The energy transmission of heat by convection is generated when hot molecules move from one side to another. Example: the wind.
Unit of measurement of thermal energy
The units for measuring thermal energy are the same units that are used to measure energy since it is still a form of energy.
We measure the energy in Joules (J) according to the international system. When we talk about heat energy we usually use calories (cal) referred to the amount of energy required to raise one degree Centigrade in a gramme of water. A calorie is equal to 4.18 Joules.
Last review: November 22, 2016