OCR · A-Level · Physics
Course version: H556 · Version from Sept 2015
(c) temperature measurements both in degrees Celsius ( ° C) and in kelvin…
Full specification wording
Temperature: (c) temperature measurements both in degrees Celsius ( ° C) and in kelvin (K)
Temperature can be measured in degrees Celsius (°C) or in kelvin (K).
Checked against the OCR H556 specification (opens in a new tab) on .
- Point 3 of 4
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Temperature can be measured in degrees Celsius (°C) or in kelvin (K). The Celsius scale is defined by the ice point (0 °C) and steam point (100 °C) of water at standard atmospheric pressure. The kelvin is the SI unit of thermodynamic temperature, with 0 K defined as absolute zero. The two scales have the same size degree, so a temperature change of 1 °C equals a change of 1 K. To convert from Celsius to kelvin, add 273 (approximately). Always check whether the question requires an exact conversion or an approximate one, and ensure you use the correct symbol and unit.
What earns the marks
- Temperature can be measured in degrees Celsius (°C) or in kelvin (K).
- The Celsius scale is defined by the ice point (0 °C) and steam point (100 °C) of water at standard atmospheric pressure.
- The kelvin is the SI unit of thermodynamic temperature, with 0 K defined as absolute zero.
- A temperature change of 1 °C is equal to a temperature change of 1 K.
- To convert from Celsius to kelvin, add 273 (approximately).
Common mistakes and how to put them right
Misunderstanding: the Celsius and kelvin scales have different degree sizes.
Put it right: The size of one degree Celsius is the same as one kelvin, so temperature differences are numerically equal.
Misunderstanding: 0 °C is the same as 0 K.
Put it right: 0 °C is approximately 273 K, while 0 K is absolute zero.
Misunderstanding: to convert from kelvin to Celsius, add 273.
Put it right: Convert from kelvin to Celsius, subtract 273 (approximately).
Exam tips
- Remember the approximate conversion: T(K) ≈ θ(°C) + 273.
- Check that you are using the correct unit symbol: °C for degrees Celsius and K for kelvin (no degree symbol).
- When converting a temperature difference, the numerical value is the same in °C and K.
Try the lesson
The start of the Temperature: (c) temperature measurements both in degrees Celsius ( ° C) and in kelvin (K) lesson, made from checked teaching notes for this specification point.
Listen
Temperature can be measured in degrees Celsius (°C) or in kelvin (K). The Celsius scale is defined by the ice point (0 °C) and steam point (100 °C) of water at standard atmospheric pressure. The kelvin is the SI unit of thermodynamic temperature, with 0 K defined as absolute zero. The two scales have the same size degree, so a temperature change of 1 °C equals a change of 1 K. To convert from Celsius to kelvin, add 273 (approximately). Always check whether the question requires an exact conversion or an approximate one, and ensure you use the correct symbol and unit. A strong answer earns marks for these points. Temperature can be measured in degrees Celsius (°C) or in kelvin (K). The Celsius scale is defined by the ice point (0 °C) and steam point (100 °C) of water at standard atmospheric pressure. The kelvin is the SI unit of thermodynamic temperature, with 0 K defined as absolute zero. A temperature change of 1 °C is equal to a temperature change of 1 K. A common slip: Misunderstanding: the Celsius and kelvin scales have different degree sizes. Instead, the size of one degree Celsius is the same as one kelvin, so temperature differences are numerically equal. Exam tip: Remember the approximate conversion: T(K) ≈ θ(°C) + 273.
See it
Key words
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Celsius scale
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Kelvin
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Absolute zero
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Conversion between temperature scales
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See every definition
- Celsius scale
- Scale defined by the ice point (0 °C) and steam point (100 °C) of water at standard atmospheric pressure.
- Kelvin
- The SI unit of thermodynamic temperature, with 0 K defined as absolute zero.
- Absolute zero
- The value 0 K, which defines the kelvin scale.
- Conversion between temperature scales
- To convert from Celsius to kelvin, add 273 (approximately); to convert from kelvin to Celsius, subtract 273 (approximately).
Label the diagram
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