The unit in one line
What temperature really measures, what heat does to a body when it arrives, and what a gas will and will not give back as work. 7 of Physics's 50 questions over six chapters.
The chapters
| Chapter | What it covers | Read |
|---|---|---|
| Thermal energy, heat, temperature and thermometers | Heat against temperature, the zeroth law, conduction, convection and radiation, the Stefan–Boltzmann law, and the three thermometers with their limits | 18 min |
| Thermal expansion | Linear, superficial and cubical expansion of solids, and the real and apparent expansion of liquids | 14 min |
| Quantity of heat | Heat capacity and specific heat capacity, calorimetry and mixtures, the latent heats, and the triple point | 14 min |
| Ideal gas | The molecular model of a gas, the gas laws and the equation of state, rms speed, and the energy of a molecule | 17 min |
| First law of thermodynamics | Systems, internal energy and work done by a gas, and the isothermal, adiabatic, isochoric and isobaric processes | 17 min |
| Second law of thermodynamics | Heat engines and the internal-combustion cycles, refrigerators and their coefficient of performance, and entropy | 17 min |
About an hour and forty minutes in all. Seven marks over six chapters means roughly one question a chapter, so there is no chapter here you can afford to leave unread.
Read in this order
Syllabus order works, and the unit divides cleanly in half.
The first three chapters are about heat arriving at a body. Thermometers comes first because it settles what temperature is and how the scales convert, which every later chapter assumes. Thermal expansion and quantity of heat can then be read in either order; both are calculation chapters that reward one careful reading over three skims.
The last three are one continuous argument and must be read in order. Ideal gas builds the molecular picture and the equation of state; the first law cannot define the work done by a gas without it; and the second law only makes sense once the first has shown that energy accounting alone permits engines that never actually work. If you are short of time, this second half is the higher-yield end of the unit.
How it is asked
MEC sets the paper roughly half recall, a third understanding and a fifth application. Recall here is a fixed point, a unit, or which thermometer suits which job. Understanding is why the apparent expansion of a liquid is less than its real expansion, or why no engine reaches the Carnot efficiency. Application is a mixture whose final temperature you must find, a gas taken round a cycle, or an efficiency from two temperatures in kelvin — and the commonest lost mark in the whole unit is a temperature left in degrees Celsius.
Then practise
Each chapter has a fixed-length chapter test under Practice › Topics, drawn from questions written to that chapter's scope. Sit it after reading; a second sitting a week later shows whether it stuck.