Temperature
A measure of the average kinetic energy of particles in a substance, indicating how hot or cold the substance is. Temperature is measured in kelvin (K) on the absolute scale (SI unit) or in degrees Celsius (°C). Absolute zero (0 K = −273.15°C) is the lowest possible temperature; at this point, particle motion is minimal (quantum effects aside).
Formula
T(K) = θ(°C) + 273.15
Real World
NASA engineers designing the James Webb Space Telescope specified its detectors must operate near 6 K (−267 °C) — using the Kelvin scale was essential because ratios of thermal energy directly governed the telescope's infrared sensitivity.
Exam Focus
Always convert Celsius to kelvin before using any gas law or thermal energy equation; leaving temperatures in °C is penalised every time.
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