⚡
Thermodynamics
Heat, laws of thermodynamics, Carnot engine
Key Concepts
- Zeroth law: thermal equilibrium defines temperature
- First law: ΔU = Q − W (energy conservation)
- Second law: heat flows spontaneously from hot to cold; entropy increases
- Isothermal: constant T (ΔU = 0); Adiabatic: Q = 0; Isochoric: W = 0; Isobaric: W = PΔV
- Carnot engine has maximum efficiency for given temperature limits
Important Formulae
| First law of thermodynamics | ΔU = Q − W |
| Carnot efficiency | η = 1 − T_L / T_H |
| Ideal gas law | PV = nRT |
| Specific heats relation | C_p − C_v = R; γ = C_p/C_v |
| Work in isothermal process | W = nRT ln(V₂/V₁) |
| Work in adiabatic process | W = (P₁V₁ − P₂V₂)/(γ − 1) |
Quick Tips
- γ = 5/3 for monatomic gas, 7/5 for diatomic gas.
- Refrigerator COP = T_L / (T_H − T_L); heat pump COP = T_H / (T_H − T_L).
- Entropy change ΔS = Q_rev / T; total entropy of universe never decreases.
Practice Questions
Practice 20 randomly selected NEET questions on Thermodynamics. Answers are revealed after each question.
Start Practice →