Absolute Temperature
- The Kelvin temperature scale begins at absolute zero
- Absolute zero, or 0 K, is equal to −273 °C
- An increase of 1 K is the same change as an increase of 1 °C
- It is not possible to have a temperature lower than 0 K
- This means a temperature in Kelvin will never have a negative value
- To convert between temperatures θ in the Celsius scale, and T in the Kelvin scale, use the following conversion:
θ / °C = T / K − 273
T / K = θ / °C + 273
Kelvin Scale and Celsius Scale
Conversion chart relating the temperature on the Kelvin and Celsius scales
Worked example
Convert the following values between the Kelvin (absolute) and Celsius scales of temperature.
(a)
0 K = ...................... °C
(b)
0 °C = ...................... K
(c)
20 °C = ...................... K
Answer:
(a)
Step 1: Choose whether to add or subtract 273 to the value
- The question is in Kelvin therefore subtract 273 to convert to Celsius
Step 2: Do the calculation
Step 3: Write the answer with units
- 0 K = −273 °C
(b)
Step 1: Choose whether to add or subtract 273 to the value
- The question is in Celsius therefore add 273 to convert to kelvin
Step 2: Do the calculation
Step 3: Write the answer with units
- 0 °C = 273 K
Part (c)
Step 1: Choose whether to add or subtract 273 to the value
- The question is in Celsius therefore add 273 to convert to kelvin
Step 2: Do the calculation
Step 3: Write the answer with units
- 20 °C = 293 K