Temperature · revision map · A-Level 9702, Topic 14
TOPIC 14 · TEMPERATURE
CAMBRIDGE INTERNATIONAL AS & A LEVEL PHYSICS 9702 · ONE-PAGE REVISION MAP
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TEMPERATURE14
Thermal Equilibrium
Thermal energy flows from a hotter region to a colder one. Two bodies in thermal equilibrium share one temperature with no net flow.
T(hot) > T(cold) → net flow hot to cold- Temperature sets the direction of energy flow, not how much energy a body holds.
Temperature Scales
The thermodynamic (Kelvin) scale is independent of any substance; absolute zero is its true fixed point.
T / K = θ / °C + 273.15- Absolute zero: 0 K = −273.15 °C.
- An interval is equal on both scales: 1 K = 1 °C.
Specific Heat & Latent Heat
Count the energy a temperature change or a change of state costs.
- Specific heat capacity c: energy to raise the temperature of 1 kg by 1 K (a sloping part).
- Specific latent heat L: energy to change the state of 1 kg at constant temperature (a flat plateau).
Using the Ideas · Method
Pick the right term for each leg of a change.
- Temperature changing, one state: E = mcΔθ.
- State changing, constant temperature: E = mL.
- A full change (ice to steam) adds each leg in turn.
- A heater supplies energy at a rate: E = Pt when losses are zero.