The term of temperature makes one spontaneous think of physiological experiences whilst touching or approaching some solid. Some of them may be described as cold, cool or tepid, others as hot or warm. Warmer bodies transfer heat to other cooler bodies. Both bodies tend to equalize their temperatures, approaching a new common intermediate temperature. Thus the correctness of the definition, given to temperature by the Scotsman James Clerk Maxwell, may be seen. He stated that the temperature of a body is its thermal state, retarded as a measure of its ability to transfer heat to other bodies. This definition forms the basis of all of the international temperature scales in use both present and in the past. |
Temperature
is the effect of heat energy, which determines the thermal state of the
given substance. In other words, we can say that the temperature
determines the degree of hotness or coldness of a substance.
An objective measurement of temperature is based on the Zeroth law of thermodynamics.
It states that if two bodies A and B are in thermal equilibrium with a third body C , then A and B are in thermal equilibrium with each other. Thus, the thermal equilibrium of two bodies A and B kept in contact for a long time can be tested by third body C which is a device used to measure temperature, such a device is called thermometer.
If
a body is at a higher temperature than its surroundings, it means that
heat energy will flow out of the body and vice versa. Based on the
kinetic model of matter, temperature can be defined as the average of
the kinetic energy of all the molecules of a substance. We can say that
temperature is directly proportional to the heat energy in a given mass
of the body as long as the state of the body does not change. In this
section we will learn more about temperature conversion.
There are different scale of temperature measurement.
The Celsius Scale
The Celsius Scale
This scale is associated with Celsius and is generally used in all scientific work. On this scale of temperature, the ice-point is taken as zero degree Celsius (written 0^{0} C) and the stream point is taken as 100^{0} C. The interval between the lower and upper fixed points is divided into 100 equal parts, each part corresponds to a difference of temperature of 1^{0} C. The scale was called " Centigrade scale " until 1948, when the Ninth General conference on weights and Measures decided that the name should be changed as " Celsius scale".
The following are the temperature conversion formulas:
From Celsius(°C) | To Celsius(°C) | |
Fahrenheit | [°F] = [°C] $\times$ $\frac{9}{5}$+ 32 | [°C] = ([°F] - 32) $\times$ $\frac{5}{9}$ |
Kelvin | [K] = [°C] + 273.15 | [°C] = [K] - 273 |
The Fahrenheit Scale
This scale was invented by Fahrenheit. It is used for clinical and meteorological purposes. On this scale of temperature, the ice-point is taken as 32 degree Fahrenheit (written as $32^{0}$F) and the steam-point is taken as $212^{0}$ F. The interval between the two fixed points is divided into 180 equal parts, each part corresponds to a difference of temperature of 1^{0 }F.
The following are the temperature conversion formulas:
From Fahrenheit | To Fahrenheit | |
Celsius | [^{o}C] = ([^{o}F] - $32$) $\times$ $\frac{5}{9}$ | [^{o}F] = [^{o}C] $\times$ $\frac{9}{5}$ + $32$ |
Kelvin | [K] = ([^{o}F] + 459.67) $\times$ $\frac{5}{9}$ | [^{o}F] = [K] $\times$ $\frac{9}{5}$- 459.67 |
The Kelvin Scale
Load Kelvin defined a scale based on thermodynamic principles that dose not depends on the properties of any particular substance. The unit of the Kelvin or thermodynamic temperature scale is called the Kelvin. The kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of the water.
The zero of this scale is the temperature at which the molecular motion ceases and average kinetic energy of molecules becomes zero. This temperature is called absolute zero. The kelvin scale is also known as absolute scale of temperature.
The following are the temperature conversion formulas:
From kelvin | To Kelvin | |
Celsius | [^{o}C] = [K] - 273.15 | [k] = [^{o}C] + 273.15 |
Fahrenheit | [^{o}F] = [K] $\times$ $\frac{9}{5}$ - 459.67 |
[K] = ([^{o}F] + 459.67 ) $\times$ $\frac{5}{9}$ |
Solved Examples
Question 1: Convert the normal body temperature, 98.6°F, into °C and K.
Solution:
Solution:
Given
Temperature in Fahrenheit that is 98.6°F
[°C] = ([°F] -32) $\times$ $\frac{5}{9}$
So,
[°C] = ([98.6] -32) $\times$ $\frac{5}{9}$
°C = 37.0
To solve for Kelvin
K = °C +273.15
K = 37.0 + 273.15
K = $310.15$
That is 98.6°F = 37 °C = 310.15 K
Question 2: Convert 56 °F to K.
Solution:
Solution:
From the question, it is given that,
F = 56°F
We have Fahrenheit to Kelvin Formula:
F = 56°F
We have Fahrenheit to Kelvin Formula:
K = (°F) + 459.67 ) $\times$ $\frac{5}{9}$
= (56 + 459.67) $\times$ $\frac{5}{9}$
= 286.483
Question 3: Convert 48 K to Celsius scale.
Solution:
Solution:
Given temperature in kelvin is given as,
F = 48K
To convert K to Celsius scale Formula is
F = 48K
To convert K to Celsius scale Formula is
°C = K - 273.15
= 48 - 273.15
= -225.15 °C