Thermodynamics Cycle Shortcut ⚡ JEE Concept
❓ Concept Question In a cyclic thermodynamic process , how do we determine the work done by the gas from a P–V diagram ? 🖼 Concept Image ✍️ Short Concept In thermodynamics, when a gas undergoes a complete cycle , the work done equals the area enclosed in the P–V graph . Geometry directly gives the answer. 🔷 Step 1 — Cyclic Process Golden Rule 💯 For cyclic process: Initial state = Final state So, Δ U = 0 \Delta U = 0 From First Law: Q = W Q = W 👉 Net heat supplied equals net work done. 🔷 Step 2 — Work Done in a Cycle Work done by gas: W = ∮ P d V W = \oint P\,dV Graphically: W = Area enclosed in P–V diagram \boxed{W = \text{Area enclosed in P–V diagram}} ⚠️ Path calculation usually not needed. 🔷 Step 3 — Direction of the Cycle Direction determines the sign of work . Clockwise cycle → W > 0 W > 0 Work done by gas . Anticlockwise cycle → W < 0 W < 0 Work done on gas . 🔷 Step 4 — Shape of the Loop Area depends on...