How is Celsius scale different from Kelvin scale?

Short Answer

The Celsius scale and Kelvin scale are two different temperature scales. The Celsius scale is commonly used in daily life and is based on the freezing point (0°C) and boiling point (100°C) of water. The Kelvin scale is used mainly in science and starts from absolute zero, the lowest possible temperature, marked as 0 K.

Both scales increase at the same rate, but their starting points are different. Celsius can have negative values, while Kelvin never has negative values. To convert Celsius to Kelvin, we add 273.15. These differences show how the two scales are used for different purposes.

Detailed Explanation :

Difference between Celsius and Kelvin Scale

The Celsius scale and Kelvin scale are two important temperature scales used around the world. Although they both measure temperature, they are designed for different purposes and start from different reference points. Understanding how they differ helps us use temperature correctly in daily life, science, and technology.

The Celsius scale is the most commonly used scale for everyday temperature measurement. It is simple, easy to use, and based on the physical properties of water. The lower fixed point of the Celsius scale is the freezing point of water, which is marked as 0°C, and the upper fixed point is the boiling point of water, marked as 100°C. These two points are divided into 100 equal parts called degrees Celsius. Because it is based on the behavior of water, the Celsius scale is well suited for weather reports, cooking, and household use.

The Kelvin scale, on the other hand, is mainly used in scientific laboratories, physics, chemistry, and advanced research. The Kelvin scale starts at absolute zero, the temperature at which the motion of particles becomes minimum. This temperature is the lowest that nature allows and is written as 0 K. Unlike Celsius, the Kelvin scale does not use the degree symbol (°). It is considered an absolute scale because it is based on natural physical laws rather than properties of water.

Reference Points of Both Scales

The difference between Celsius and Kelvin scales becomes clear when we compare their reference points:

  • In the Celsius scale:
    • Freezing point of water = 0°C
    • Boiling point of water = 100°C
  • In the Kelvin scale:
    • Absolute zero = 0 K
    • Freezing point of water = 273 K
    • Boiling point of water = 373 K

This shows that the Kelvin scale is simply the Celsius scale shifted upward by 273 units. Both scales have equal size divisions, meaning that a change of 1°C equals a change of 1 K.

Why Kelvin Cannot Be Negative

The Kelvin scale starts from absolute zero, which is the lowest possible temperature in the universe. Since no temperature can be below absolute zero, the Kelvin scale never has negative values. This makes Kelvin an ideal scale for thermodynamics and physical laws. Celsius, however, can have negative values because it is based on everyday conditions. For example, temperatures in winter in many places drop below 0°C.

Use of Celsius and Kelvin in Daily Life and Science

The Celsius scale is widely used in:

  • Weather forecasting
  • Room temperature monitoring
  • Cooking
  • Refrigerators and air conditioners
  • Medical thermometers

This is because Celsius is easy to understand and practical for daily use.

The Kelvin scale is used in:

  • Physics experiments
  • Chemistry laboratories
  • Thermodynamics
  • Calculations involving gas laws
  • Astronomy (temperature of stars and space objects)

Kelvin allows scientists to measure extremely low or high temperatures without dealing with negative values.

Conversion Between Celsius and Kelvin

Since both scales increase at the same rate, converting between them is easy:

  • Kelvin (K) = Celsius (°C) + 273.15
  • Celsius (°C) = Kelvin (K) – 273.15

For example:

  • 25°C = 298.15 K
  • 300 K = 26.85°C

This simple conversion helps students, scientists, and engineers compare temperatures across both scales.

Examples to Understand the Difference

  1. If the temperature outside is 30°C, in Kelvin it becomes 303 K.
  2. If the temperature of a gas in a lab experiment is 500 K, in Celsius it becomes 226.85°C.
  3. Water freezes at 0°C but in Kelvin this becomes 273 K.
  4. Kelvin is required to use in formulas like gas laws (PV = nRT), while Celsius cannot be used directly.

These examples show that Celsius is ideal for daily activities, while Kelvin is essential for scientific measurements.

Why the Kelvin Scale Is More Scientific

The Kelvin scale is considered more scientific because:

  • It begins at the natural lower limit of temperature (absolute zero).
  • It avoids negative values, making calculations simpler.
  • It is directly linked to particle energy.
  • It is used in all thermodynamic equations and gas laws.

Because of these reasons, Kelvin is the preferred scale in scientific research.

Conclusion

The Celsius scale and Kelvin scale both measure temperature, but their starting points and uses are different. Celsius is based on the freezing and boiling points of water and is used in daily life. Kelvin begins at absolute zero and is used in scientific work. While Celsius can be negative, Kelvin cannot. Both scales increase at the same rate, and easy formulas help convert between them. Understanding these differences helps us use the correct temperature scale in daily and scientific applications.