JEE Main 2022 · 27 Jul · Shift 2 · Physics Q38

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PhysicsSingle correct+4 / -1Question 38 of 90

In 1 $^{\text{st}}$ case, Carnot engine operates between temperatures 300 K and 100 K. In 2 $^{\text{nd}}$ case, as shown in the figure, a combination of two engines is used. The efficiency of this combination (in 2 $^{\text{nd}}$ case) will be :

2nd case: a reservoir at 300 K, engine E1, a reservoir at 200 K, a second engine, and a sink at 100 K, in series.

same as the 1

^{ ext{st}}

case.

always greater than the 1

^{ ext{st}}

case.

always less than the 1

^{ ext{st}}

case.

may increase or decrease with respect to the 1

^{ ext{st}}

case.

Answer and worked solution

Official answer: A

Combined efficiency. $1-\frac23\cdot\frac12=\frac23$ , the same as a single engine between 300 K and 100 K.

(A)

Topics:Carnot cycle Heat engines and refrigerators

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JEE Main 2022 · 27 Jul · Shift 2, Physics question 38