A Carnot engine (E) is working between two temperatures 473K and 273K. In a new system two engines - engine E₁$\mathrm{E}_1$ works between 473K to 373K and engine E₂$\mathrm{E}_2$ works between 373K to 273K. If η₁₂$\eta_{12}$ , η₁$\eta_1$ and η₂$\eta_2$ are the efficiencies of the engines E, E₁$\mathrm{E}_1$ and E₂$\mathrm{E}_2$ , respectively, then
A.η₁₂ < η₁ + η₂$\eta_{12} < \eta_1 + \eta_2$
B.η₁₂ = η₁η₂$\eta_{12} = \eta_1\eta_2$
C.η₁₂ = η₁ + η₂$\eta_{12} = \eta_{1} + \eta_{2}$
D.η₁₂ ≥ η₁ + η₂$\eta_{12} \geq \eta_1 + \eta_2$
Solution & Explanation
Related Formula
η = 1 - TLTH$$\eta = 1 - \frac{\mathrm{T}_L}{\mathrm{T}_H}$$
Core Logic
Let's compute the efficiency parameters explicitly:
Practice past-year questions one chapter at a time. Pick an exam → subject → chapter and get every PYQ for that topic — pulled together from all past papers — with the chapter's key formulas alongside.
