Heat Energy is defined as the degree of hotness or coldness. it is a type of energy that travels from one place to another place. It usually travels from higher potential to the low potential. The energy is a transfer in three ways (conduction, convection and radiation).
Heat energy transferred from one body to another as the result of a temperature difference. If two bodies that having different temperatures have come closer together than energy is transferred, so heat starts to flow from the hotter body to the colder body. It increases the temperature of the colder object and decreases the temperature of the hotter object.
A substance may absorb heat without an increase in temperature because it changes from one physical state to another physical state, as from a solid to a vapors (sublimation), from a liquid to a vapors (boiling), from a solid to a liquid (melting) or from one solid form to another solid form(usually called a crystalline transition).
The main difference between heat and temperature is that heat being a form of energy and temperature is a measurement of the amount of energy that presents in a body.
Units of Heat
The SI unit for heat energy is joule (J). It is also measured in the calorie (cal), which is defined as “the amount of heat required to increase the temperature of 1 gram of water from 14.5 degrees Celsius to 15.5 degrees Celsius”.
Sign Conventions for Heat Energy Transfer
In mathematical equations, the amount of heat transferred is generally denoted by the symbol Q. Heat transfer indicated by either a positive or negative number. When the heat is released into the surroundings is written as a negative quantity (Q < 0) and heat is absorbed from the surroundings is written as a positive value (Q > 0).
Ways of Transferring Heat
There are three ways to transfer heat:
Convection is a process, in which energy is transferred through the movement of the particles of the medium. In the home, when the air is heated, the particles that gain heat energy allowing moving faster, warming the cooler particles. Since hot air is less dense than cold air and it will rise. As the cooler air falls down, it can be drawn into our heating area which will again allow the faster particles to heat up the air. This is considered as a circular flow of air.
Conduction process is the transfer of energy from one solid to another, basically, two things that are touching to each other so heat is a transfer between these two objects.
Radiation is a form of electromagnetic energy. In this process, heat moves through places where there are no molecules present. Any object whose heat can be felt without any direct connection is radiating.
Heat Energy Examples
- The biggest example of heat energy is the sun. The sun radiates heat energy to warm the planet earth.
- When the burner is very hot it act as a source of heat energy. Anything placed onto the burner and warmed, whether a pot of tea or a skillet for frying fishes, also become sources of heat energy.
- Automobile fuels such as gasoline are also sources of it, as is the hot engine of automobiles.