Two Carnot engine A and B are operated in series. The engine A receives that heat from the source at temperature T₁ and rejects the heat to the sink at temperature T. The second engine B receives the heat at temperature T and rejects to its sink at temperature T₂. For what value of T the efficiencies of the two engines are equal?

Options

(a) T₁ + T₂ / 2
(b) T₁ – T₂ / 2
(c) T₁ T₂
(d) √(T₁ T₂)

Correct Answer:

√(T₁ T₂)

Explanation:

Efficiency of engine A, ?￢ﾂﾁ = 1 – T / T₁,
Efficiency of engine B, ?￢ﾂﾂ = 1 – T₂ / T,
Here, ?￢ﾂﾁ = ?￢ﾂﾂ
T / T₁ = T₂ / T ⇒ T = √T₁T₂