Temperature is the measure of the degree of heat of a substance, that is, its level of heat energy. It is measured using an arbitrary scale from absolute zero, where the molecules theoretically stop moving. It is also the degree of heat and cold.
The heat energy is the manifestation of the kinetic energy of the particles, atoms and molecules, of which the body in question is composed.
When heat energy is communicated from one body to another, a certain amount of heat is used to perform a job, usually dilation, and the rest to increase its temperature, the latter component directly related to increasing the kinetic energy, either translation or of vibration, of the atoms and molecules that compose it.
The temperature is a magnitude with which it is not possible to use a standard as a unit of measurement. For this reason the temperature measurement is based on the evaluation of other types of physical quantities when they gain or lose heat energy, such as the increase or decrease in volume or pressure, the electrical resistance of the conductive metals, the contact voltage of two different metals or the magnetic susceptibility of certain paramagnetic salts.
The heat energy is transmitted from cold to hot bodies until a steady state is reached and transmission ceases.
Taking the defrost temperature as zero and about 100 the boiling water temperature, the Celsius or Celsius scale is established. Fahrenheit adopted the melting temperature of a mixture of water and ammonia salt as zero and 212 the boiling water temperature.
The general conference of weights and measures of 1954 decided, arbitrarily, to take as a fixed point the so-called triple point of water, the one in which it coexists in its three states, solid, liquid and vapor, and arbitrarily assign the value of 273, 15 at its temperature. The unit thus formed is called Kelvin and, in it, there are no negative temperatures.
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