Key Differences Between Celsius, Fahrenheit, Kelvin, and Rankine Scales
Temperature is one of the seven fundamental physical quantities in physics. A substance's temperature is defined as its degree of hotness. As a result, temperature refers to how hot or cold a body is. Different temperature scales, such as the Celsius, Kelvin, and Fahrenheit scales, are used to express a substance's temperature. To convert temperature from one scale to another, there are several formulas. The numerous forms of temperature scales and their formulas will be discussed here.
What is Temperature?
The degree of hotness of a body is measured by temperature. We can compare two bodies and determine one is hotter than the other based on their temperature values. Kelvin is the SI unit of temperature (K). Celsius and Fahrenheit are the two temperature units. Heat energy transfers from the body with a higher temperature to the one with a lower temperature when two bodies with differing temperatures come into contact. When two bodies of the same temperature come into touch with each other, no heat energy is transferred between them.
Different types of Temperature Scales
Temperature scales are divided into three categories. The Celsius, Fahrenheit, and Kelvin scales are the three. The formula can be used to convert a temperature value from one scale to another. Let's take a closer look at the many types of temperature scales.
Celsius Temperature Scale
There is one lower fixed point of 0 degrees Celsius and one upper fixed point of 100 degrees Celsius on the Celsius temperature scale. The centigrade temperature scale is another name for the Celsius temperature scale. It's because the lower fixed point of 0 degrees Celsius and the upper fixed point of 100 degrees Celsius are separated by a hundred degrees. The lower fixed point in the Celsius temperature system is 0 degrees Celsius, which is the freezing point of water at 1 atm atmospheric pressure. The upper fixed point in the Celsius temperature scale is 100 degrees Celsius, which is the boiling point of water at normal atmospheric pressure. Anders Celsius, a Swedish astronomer, established the Celsius temperature scale. The temperature in degrees Celsius is represented by the symbol °C. As a result, we can write that water's freezing point is 0 degrees Celsius and its boiling point is 100 degrees Celsius. All around the world, the Celsius temperature scale is frequently used.
Fahrenheit Temperature Scale
Daniel Gabriel devised the Fahrenheit temperature scale in 1744 while working on alcohol and mercury thermometers. In Fahrenheit, the temperature is expressed in degrees Fahrenheit (°F). The freezing point of water at normal atmospheric pressure is 32 degrees Fahrenheit, which is the lower fixed point on the Fahrenheit temperature scale. The boiling point of water at normal atmospheric pressure is 212 degrees Fahrenheit, which is the upper fixed point on the Fahrenheit temperature scale. Between the lower fixed point of 32 °F and the higher fixed point of 212 °F, there are 180 intervals. In the United States, the Fahrenheit temperature scale is widely used.
Kelvin Temperature Scale
Lord Kelvin invented the Kelvin scale in 1848. Kelvin is the S.I. temperature unit, denoted by K without a degree notation. The Kelvin temperature scale was inspired by the concept of absolute zero. The absolute zero temperature is the lowest temperature that any substance in the cosmos can reach. It is the lowest temperature at which the molecules have the least amount of energy. In the kelvin temperature scale, absolute zero is equal to 0 K. In the Kelvin temperature scale, absolute zero K equals -273.15 °C. In the Kelvin temperature scale, 1 K equals 1/273.16 of the temperature of the triple point of water.
Water has a freezing point of 273.15 K and a boiling point of 373.15 K on the kelvin temperature scale.
The Conversion of Temperature Scales Using the Formula
The temperature of a body can be converted from one temperature scale to another. Let's have a look at a few different temperature scale formulas.
The relation between the temperature in degree Celsius and the temperature in degree Fahrenheit is given by,
$\Rightarrow T_{^oF}= \frac{9}{5} \times T_{^oC} + 32$
Where,
$T_{^oF}$ - The temperature in Fahrenheit scale.
$T_{^oC}$ - The temperature in Celsius scale
The relation between the temperature in degree Celsius and temperature in kelvin scale is given by,
TK = 273.15 + $T_{^oC}$
Where,
TK - The temperature in the Kelvin scale.
$T_{^oC}$ - The temperature in Celsius scale
The relation between the temperature in Fahrenheit scale and the temperature in kelvin scale is given by,
$T_K= \frac{5}{9}\times \left ( T_{^oF} - 32 \right ) + 273.15$
Where,
$T_{^oF}$ - The temperature in Fahrenheit scale.
TK - The temperature in kelvin scale
Examples:
1. The temperature of a body is given as 80 ℃. Express this temperature on the Fahrenheit scale.
Ans:
The temperature of the body in degree Celsius = $T_{^oC}$ = 80oC
The relation between the temperature in degree Celsius and the temperature in degree Fahrenheit is given by,
$\Rightarrow T_{^oF}= \frac{9}{5} \times T_{^oC} + 32$...(1)
Where,
$T_{^oF}$ - The temperature in Fahrenheit scale.
$T_{^oC}$ - The temperature in Celsius scale
Substitute the value for temperature in degree Celsius in the equation (1) and simplify to calculate the temperature in Fahrenheit scale.
$\Rightarrow T_{^oF}= \frac{9}{5} \times T_{^oC} + 32$
$\Rightarrow T_{^oF}= \frac{9}{5} \times 80 + 32$
$\Rightarrow T_{^oF}= 144 + 32$
$\Rightarrow T_{^oF}= 176^oF$
⇒T℉ = 95 T℃ + 32
⇒T℉ = 95 80 + 32
⇒T℉ = 144 + 32
⇒T℉ = 176 ℉
Therefore, the temperature of the body in Fahrenheit scale is 176 ℉
2. Find the corresponding temperature for 298.15 K on the Celsius scale and Fahrenheit.
Ans:
The temperature in kelvin scale = TK = 298.15 K
The relation between the temperature in degree Celsius and temperature in kelvin scale is given by,
$\Rightarrow T_{^oF}= 273.15 \times T_{^oC}$...(1)
Where,
TK - The temperature in the Kelvin scale.
$T_{^oC}$ - The temperature in Celsius scale
Substitute the values for temperature in Kelvin scale in equation (1) and simplify to calculate the temperature in Celsius scale.
$\Rightarrow T_{k}= 273.15 + T_{^oC}$
$298.15 = 273.15 + T_{^oC}$
$T_{^oC} = 25^oC$
Therefore, the temperature in the Celsius scale is 25oC
The temperature in Celsius scale $T_{^oC}$ = 25oC
The relation between the temperature in degree Celsius and the temperature in degree Fahrenheit is given by,
$\Rightarrow T_{^oF}= \frac{9}{5} \times T_{^oC} + 32$...(2)
Where,
$T_{^oF}$ - The temperature in Fahrenheit scale.
$T_{^oC}$ - The temperature in Celsius scale
Substitute the value for temperature in degree Celsius in equation (2) and simplify to calculate the temperature in Fahrenheit scale.
$\Rightarrow T_{^oF}= \frac{9}{5} \times T_{^oC} + 32$
$\Rightarrow T_{^oF}= \frac{9}{5} \times 25 + 32$
$\Rightarrow T_{^oF}= 45 + 32$
$\Rightarrow T_{^oF}= 77{^oF}$
Therefore, the temperature of the body in Fahrenheit scale is 77 ℉
Conclusion
A body's temperature is a measurement of how hot it is. To express the temperature of a body, we use many temperature scales. The Celsius temperature scale, Fahrenheit temperature scale, and Kelvin temperature scale are three different forms of temperature scales. Using the formulas given above, we may convert the temperature of a body in one temperature scale to another temperature scale. On the Celsius scale, water has a freezing point of 0°C, 32°F on the Fahrenheit scale, and 273.15 K on the Kelvin scale. At normal atmospheric pressure, the boiling point of water is 100°C on the Celsius scale, 212°F on the Fahrenheit scale, and 373.15 K on the Kelvin scale. As a result, the temperature of a body has distinct values on different temperature scales.
FAQs on Types of Temperature Scales and Their Formulas Explained
1. What are the three main temperature scales and what are they based on?
The three primary temperature scales are Celsius (°C), Fahrenheit (°F), and Kelvin (K).
- The Celsius scale is a centigrade scale based on the freezing point (0°C) and boiling point (100°C) of water at standard atmospheric pressure.
- The Fahrenheit scale defines the freezing point of water as 32°F and the boiling point as 212°F.
- The Kelvin scale is an absolute thermodynamic scale, where 0 K (absolute zero) is the theoretical point at which all molecular motion ceases. It is the SI unit of temperature.
2. How do you convert a temperature from Celsius to Fahrenheit?
To convert a temperature from degrees Celsius (°C) to degrees Fahrenheit (°F), you use the following formula: °F = (°C × 9/5) + 32. For example, to convert the normal human body temperature of 37°C to Fahrenheit, you would calculate (37 × 9/5) + 32, which equals 98.6°F.
3. What is the relationship between the Celsius and Kelvin scales?
The Celsius and Kelvin scales have a direct and simple relationship because the size of one degree is the same on both scales. A change of 1°C is equal to a change of 1 K. The formula to convert Celsius to Kelvin is: K = °C + 273.15. To convert Kelvin to Celsius, the formula is: °C = K - 273.15.
4. What is the concept of absolute zero and why is it significant?
Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. It is defined as 0 on the Kelvin scale (0 K), which is equivalent to -273.15°C or -459.67°F. Its significance lies in it being the point of minimum thermal energy, where particles theoretically stop all random motion. This makes the Kelvin scale an absolute measure of temperature, crucial for scientific calculations in thermodynamics and quantum mechanics.
5. Why does the Fahrenheit scale use 32° for the freezing point of water instead of 0°?
The Fahrenheit scale's reference points were not originally based on pure water. Daniel Fahrenheit set 0°F as the temperature of a freezing brine (saltwater) solution and initially set 96°F as the average human body temperature. Based on this scale, the freezing point of pure water happened to fall at 32°F and the boiling point at 212°F. This is different from the Celsius scale, which was logically designed around the 0° and 100° points for water's freezing and boiling.
6. In which real-world applications is each temperature scale most commonly used?
Different scales are preferred in different contexts:
- Celsius (°C): Used by most countries worldwide for daily weather reporting and in general, non-scientific contexts. It is standard in most scientific fields that do not require an absolute scale.
- Fahrenheit (°F): Primarily used for everyday temperature measurement in the United States, its territories, and a few other countries.
- Kelvin (K): Used almost exclusively in scientific fields like physics, chemistry, and astronomy. It is essential for work involving thermodynamics, gas laws, and thermal energy because it is an absolute scale.
7. Is there a temperature at which the Celsius and Fahrenheit scales are equal?
Yes, the Celsius and Fahrenheit scales are equal at -40 degrees. At this specific temperature, -40°C is the same as -40°F. This is the only point where the two scales intersect, which can be proven by setting the values for °C and °F as equal in the conversion formula and solving for the temperature.
8. What is the universal formula that relates Celsius, Fahrenheit, and Kelvin?
A universal formula can be used to show the relationship between all three scales and to convert between any of them. The formula is: (C/5) = (F - 32)/9 = (K - 273.15)/5. By taking any two parts of this equality, you can derive the conversion formula for those two scales. This equation is a fundamental tool for solving temperature conversion problems.
