We explain what temperature is, how it is measured and what scales are used. Also, types of temperatures and differences with heat.

Temperature is related to the notion of cold and heat.

What is temperature?

Temperature is a scalar quantity that is defined as the amount of kinetic energy of the particles of a mass soda, liquid or solid. The higher the speed of the particles, the higher the temperature and vice versa.

Temperature measurement is related to the notion of cold (lower temperature) and of heat (higher temperature), which can be perceived instinctively. In addition, the temperature acts as a reference value to determine the normal heat of the human body, information that is used to estimate states of Health. Heat is also used for chemical, industrial and metallurgical processes.

Temperature scales

On the Celsius scale the freezing point of water equals 0 ° C.

There are different types of scales to measure temperature. The most commons are:

  • The Celsius scale. Also known as the “centigrade scale”, it is the most used along with the Fahrenheit scale. On this scale, the freezing point of the Water equals 0 ° C (zero degrees Celsius) and its Boiling point at 100 ° C.
  • The Fahrenheit scale. It is the measure used in most English-speaking countries. On this scale, the freezing point of water occurs at 32 ° F (thirty-two degrees Fahrenheit) and its boiling point at 212 ° F.
  • The Kelvin scale. It is the measure that is usually used in science and sets "absolute zero" as the zero point, which means that the object does not give off any heat and is equal to -273.15 ° C (degrees centigrade).
  • The Rankine scale. It is the measure commonly used in the United States for measurement thermodynamic temperature and is defined by measuring degrees Fahrenheit above absolute zero, so it has no negative or subzero values.

How is the temperature measured?

Temperature is measured by thermometric magnitudes, that is, different units that represent temperature at different scales. For this, a device called a "thermometer" is used, of which there are several types depending on the phenomenon that needs to be measured, for example:

  • Dilation and contraction. There are thermometers to measure gases (gas thermometer to Pressure constant), liquids (thermometer mercury) and solid (liquid column thermometer or bimetallic), which are elements that expand at high temperatures or contract at low temperatures.
  • Variation of electrical resistance. The electrical resistances, that is, the flows of electrons that move through a conductive material, vary according to the temperature they acquire. For its measurement, electrical resistance thermometers are used, such as sensors (based on a resistance capable of transforming the electrical variation into a temperature variation) and thermoelectric thermometers (which generate motive force).
  • Thermal radiation thermometer. The radiation phenomena emitted in the industrial sector can be measured using temperature sensors such as infrared pyrometers (to measure very low refrigeration temperatures) and optical pyrometers (to measure high temperatures of furnaces and melting metals).
  • Thermoelectric potential. The union of two metals different temperatures that are subjected to different temperatures, generates an electromotive force that is converted into electric potential and is measured in volts.

Temperature types

If the body temperature exceeds 37 ° C, the individual suffers from a fever.

There are different types of temperature and, therefore, they are measured with different tools, such as:

  • Room temperature. It is the temperature that can be registered in the spaces in which the human being and for its measurement an environmental thermometer that uses Celsius or Fahrenheit values ​​is used.
  • Body temperature It is the body temperature. 36 ° C is considered a normal value for humans and if the temperature exceeds 37 ° C (or 98 ° F), the individual is considered to have a fever.

Other types of temperature measurement allow you to calculate the wind chill, for example:

  • The dry temperature. It is the ambient temperature, without taking into account the heat radiation of the environment and the humidity. It is measured with a bulb thermometer painted bright white so as not to absorb radiation.
  • The radiant temperature. It is the temperature of the surfaces and walls of a closed environment and is measured by a bulb thermometer.
  • The humid temperature. It is the temperature measured by a thermometer located in the shade, with its bulb wrapped with wet cotton and located under a current of air. Through this system, the water in the cotton evaporates and the heat is absorbed, which generates a decrease in the temperature captured by the thermometer with respect to the ambient temperature. This results in a measure of air humidity that is used to measure wind chill.

Difference between heat and temperature

Heat is the energy resulting from the movement of molecules in matter.

Although heat and temperature are closely related concepts, they are not the same.

Some differences are:

  • Its meaning. Heat is thermal energy that should be understood as heat transfer, that occurs when there is a temperature difference between two bodies. This transfer always has one direction and is from the body with the highest temperature to the one with the lowest temperature. Temperature, on the other hand, is a measure of the Kinetic energy average of molecules that make up the matter.
  • His symbol. Heat is represented by the letter Q and the temperature with the letter T.
  • Its effect.The transfer of heat to a body increases its temperature. Temperature is the average kinetic energy of the particles in that body, which increases if heat is given to it.
  • Your transmission. Heat is transmitted from one substance to another and can spread by conduction, convection, or radiation. Depending on the type of heat propagation, it will be the temperature level reached.
  • Your object for measurement. Heat is measured with a calorimeter and temperature is measured with a thermometer.
  • Your unit of measure. Heat is measured in joules, calories Y kilocalories. Temperature is measured in degrees Kelvin (k), Celsius (C) or Fahrenheit (F).

Examples of temperature

Some examples of temperatures are:

  • The engine temperature of a car that is running is 85 ° C.
  • The ambient temperature, which is considered comfortable, is between 20 ° and 25 ° C.
  • The temperature of the oven turned on to prepare a pizza is 180 ° C.
  • The temperature of the boiling water is 100 ° C.
  • The average body temperature is 36.5 ° C.
  • The temperature to reach the solidification of water to the point of becoming ice, is less than 0 ° C.
  • The temperature that is controlled by a “voltage regulator” located inside an electrical appliance, prevents it from overheating or damaging the equipment.

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