Translations of Encyclopedia about Physics

Heat

Heat is a form of energy which creates a certain feeling among humans perceived as heat. The definition of heat is the kinetic (moving) energy of atoms and molecules, which all matter is made of. The greater the quantity of energy the greater the level of heat.

By adding energy we increase the energy potential of atoms or molecules, which results in an increase in heat. Temperature is an important factor in the modification and reactive ability of all substances. Almost all substances can be found in either solid, liquid or gaseous form, something referred to as states of aggregation or phase.

If we want to describe the phase of some substance, we must also include its present temperature. One of the most important units for measuring temperature is Celsius (°C) and kelvin (K). Absolute zero (0 K or -273.15°C) is the lowest, possibly only theoretically attainable, temperature, which has not been attained yet by science. During a temperature of absolute zero, atoms and molecules should have their lowest possible energy state. In this phase, air would turn into a liquid.

If we put two objects of differing temperature next to one another, energy transfers between their atoms until the temperature between the two objects is the same, which results in a temperature balance.

If we change the energy level of some object, it also results in a change in its temperature. However, if the temperature change results in a change in its state of aggregation or its phase, its temperature does not change (during this process). In physics, this energy is called latent energy and is expended on breaking molecular bonds or is released when these bonds are created.

Heat may be exchanged between object also through radiation. At a temperature of around 25°C, each object emits infrared radiation and transfers heat to objects near to it. However, an object radiating heat loses energy (heat) in the process.

Heat can also be used when separating compounds, which are made of several elements. However, each element reacts differently to heat, based on its density, composition and structure. Because all elements change phases over different time periods, some faster and some slower, these elements can separate gradually until the final product is the pure version of the original substance.

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