#### Ques: What is the relationship between the Celsius and the Kelvin scales of temperature?

**Sol.:** The Celsius (°C) and Kelvin (K) scales are both temperature scales commonly used in scientific and everyday applications. The Celsius scale is based on the properties of water, while the Kelvin scale is an absolute temperature scale. The relationship between the Celsius and Kelvin scales can be defined as follows:

The Kelvin scale is an absolute temperature scale that starts at absolute zero, where molecular motion theoretically ceases. The Kelvin scale is directly related to the Celsius scale through the following equation:

**Kelvin (K) = Celsius (°C) + 273.15**

This equation shows that the Kelvin temperature is equal to the Celsius temperature plus 273.15. Therefore, the Kelvin scale is shifted by 273.15 units relative to the Celsius scale. Absolute zero, the point where molecular motion theoretically ceases, is defined as 0 K on the Kelvin scale or -273.15 °C on the Celsius scale.

*To convert a temperature measurement from Celsius to Kelvin, you simply add 273.15 to the Celsius value. Conversely,** to** convert a temperature from Kelvin to Celsius, you subtract 273.15 from the Kelvin value.*

For example:

To convert 25 °C to Kelvin:

Kelvin (K) = 25 °C + 273.15 = 298.15 K

To convert 100 K to Celsius:

Celsius (°C) = 100 K – 273.15 = -173.15 °C

This relationship between the Celsius and Kelvin scales allows for easy conversion between the two temperature scales and is particularly useful in scientific calculations and applications involving temperature measurements.

### Celsius Scale and kelvin Scales FAQs

The Celsius scale is a commonly used temperature scale where 0 degrees Celsius (°C) represents the freezing point of water and 100 degrees Celsius represents the boiling point of water at sea level.

The Kelvin scale is an absolute temperature scale used in scientific contexts. It starts from absolute zero, the point at which all molecular motion ceases, and is denoted by 0 Kelvin (K).

The Celsius and Kelvin scales are directly related through a simple mathematical equation. To convert a temperature from Celsius to Kelvin, you add 273.15 to the Celsius value. To convert from Kelvin to Celsius, you subtract 273.15 from the Kelvin value.

The Kelvin scale is considered an absolute temperature scale because it starts from absolute zero, the lowest possible temperature. In this scale, temperatures are proportional to the average kinetic energy of molecules, providing a measure of the total molecular energy.

The main difference is the reference point and the starting point of each scale. The Kelvin scale starts from absolute zero and does not have negative values, while the Celsius scale uses the freezing and boiling points of water as reference points and includes both positive and negative values.

The Kelvin scale is primarily used in scientific and technical fields, such as physics, chemistry, and engineering, where absolute temperature measurements and calculations are required. The Celsius scale is more commonly used in everyday life and general temperature measurements.

The Kelvin scale is useful in scientific calculations because it allows for more straightforward mathematical relationships with temperature. Many physical laws and equations, such as the ideal gas law, are simplified when temperatures are expressed in Kelvin, as it eliminates negative values and maintains a direct proportionality with energy.