• id: JTHERM-01-N15
• title: Reading P-V Diagrams and Exam Strategy
• tags: PV-diagram, strategy, cyclic

Reading P-V diagrams: (1) Work = area under curve (positive for expansion/rightward). (2) Steeper curves represent more "adiabatic-like" processes. (3) Isothermal: $PV = C$ (hyperbola). (4) Adiabatic: $PV^\gamma = C$ (steeper hyperbola). (5) Clockwise cycle: net positive work. (6) $\Delta U$ for any path between two points is the same (state function).

JEE Strategy: (1) Identify the process type first. (2) Apply the First Law: $Q = \Delta U + W$. (3) For ideal gas, $\Delta U = nC_v\Delta T$ always. (4) For cyclic processes: $\Delta U = 0$, $Q_{\text{net}} = W_{\text{net}}$. (5) For Carnot problems: ALWAYS convert to Kelvin. (6) Work in mixing of gases at different temperatures: use $T_f = (n_1C_{v1}T_1 + n_2C_{v2}T_2)/(n_1C_{v1} + n_2C_{v2})$.