Physics · Class 11 · Chapter 11

Thermodynamics

This chapter treats heat as energy and asks what rules govern turning it into work. It begins with thermal equilibrium and the zeroth law, which gives temperature its meaning, then separates internal energy (a property of the state) from heat and work (ways of moving energy). The first law, ΔQ = ΔU + ΔW, is energy conservation; it leads to specific heats, C_p − C_v = R, and the special processes: isothermal, adiabatic, isochoric, isobaric and cyclic. The second law then says what energy conservation alone does not: no engine turns heat wholly into work. The chapter closes with reversible processes and the Carnot engine, whose efficiency 1 − T₂/T₁ is the ceiling for every engine between two temperatures.