9702 · 14.2
Temperature scales flashcards
Revision flashcards for Cambridge 9702 Temperature scales (syllabus 14.2). Flip, recall, then mark a real past-paper question.
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What is the SI unit for absolute temperature?
Kelvin (K)
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How do you convert a temperature from Celsius to Kelvin?
Add 273.15 to the Celsius value ($K = C + 273.15$).
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What is absolute zero in degrees Celsius?
-273.15 °C
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What defines the Kelvin scale as an 'absolute' temperature scale?
It is independent of any substance's specific properties and starts from absolute zero, where particles theoretically have zero kinetic energy.
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Why is the Kelvin scale often preferred for calculations in thermal physics?
Thermal physics equations are based on absolute temperatures, requiring values relative to absolute zero, which the Kelvin scale provides.
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What are the two fixed points of the Celsius scale?
The melting point of pure ice (0°C) and the boiling point of pure water (100°C), both at standard atmospheric pressure.
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How does a change of 1 Kelvin relate to a change of 1 degree Celsius?
A change of 1 Kelvin is exactly equal to a change of 1 degree Celsius (ΔK = Δ°C).
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Name two physical properties that change with temperature and can be used for thermometry.
Electrical resistance, volume of a liquid, pressure of a gas, or generated voltage (e.g., in a thermocouple).
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What is the theoretical state of particles at absolute zero?
Particles possess their lowest possible energy state, theoretically having zero kinetic energy.
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Give an example of a physical law that requires temperature to be in Kelvin.
The Ideal Gas Law (pV = nRT), Stefan-Boltzmann Law (P = σAT⁴), and Wien's Displacement Law (λ_max T = constant) all require absolute temperature in Kelvin for correct calculations.