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What is Temperature?-Definition, Measurement, Scales, And Conversion

August 24, 2022
written by Adeel Abbas

The average kinetic energy of the particles in an object is a type of energy associated with motion and temperature is a measure of how hot or cold an object is.

What is Temperature?

The temperature is related to the hotness or coldness of the body. It is the method of determining the kinetic energy of particles within an object. The movement of particles is faster when the temperature is higher. The hotness of matter or radiation is expressed by the amount of temperature.

Temperature Units

The system’s international unit of temperature is kelvin which is a base unit. It is denoted by the symbol K.

Temperature is also measured in celsius. It is often convenient to use the Celsius scale, in which 0 °C corresponds very closely to the freezing point of water and 100 °C is its boiling point at sea level, for everyday applications.

Relation Between Kinetic energy and temperature

Kinetic energy is the energy the body has when it moves. Molecules have different kinetic energies because not all molecules move at the same speed. When a substance absorbs heat, the particles move faster, increasing their average kinetic energy and thus increasing their temperature.

The average kinetic energy of the particles of that substance is related to the temperature of that substance. When a substance is heated, some absorbed energy is stored within the particles, while other energy increases the motion of the particles. It is registered as an increase in the temperature of the substance.

Temperature and Heat

The average energy of the motions of the molecule in the substance is referred to as heat and the total energy of the motions is referred to as temperature.

The temperature and the heat are not the same things. The total energy of the atoms of a substance is known as heat energy. The temperature is the amount of energy that the atoms of a substance have.

Temperature Scales

Well-defined scales of measurement are what Thermometers measure temperature on. Three of the most common temperature scales are the

  • Fahrenheit scale
  • Celsius scale
  • kelvin scale

Relationship between different Temperature Scales

Conversion Equation 
Celsius to FahrenheitTFo=9/5Tco+32
Fahrenheit to CelsiusTC=5/9TF−32
Celsius to KelvinTK=TCo+273.15
Kelvin to CelsiusTCo=TK−273.15
Fahrenheit to KelvinTK=59(T(F0)−32)+273.15

How does a Thermometer Measure Temperature?

Thermometers are the most widely used instrument to measure temperature. The liquid Thermometer is the simplest of the thermometers. The glass tube is filled with a small amount of mercury. Thermal expansion is an increase in the volume of substances because of the increase in temperature.

The effect of a small temperature change on the volume of a liquid is maximized when the liquid expands in the thin tube of the thermometer. When mercury gets hotter it increases in size by an amount that is directly related to the temperature. If the temperature increases by 20 degrees, the mercury expands and moves up the scale twice as much as if the temperature increase is only 10 degrees.

It’s easy to make a Celsius scale because it’s based on the temperatures of ice and boiling water. The two fixed points are near each other. If we immerse the thermometer in boiling water, the mercury will rise to 100 °C, which is the lowest point on our scale. The intervals between 0 °C and 100°Care divided into 100°Cequally spaced intervals.

What is Absolute Zero?

The third law of thermodynamics states that at the absolute zero temperature, no energy can be removed from matter as heat. At this temperature, the matter has quantum-mechanical zero-point energy as predicted by the uncertainty principle, but it does not enter into the definition of an absolute temperature. The lowest temperature for an experiment is 100 pK, and absolute zero can only be reached very closely. The absolute zero is the same as −273.15 °C or −459.67 °F.