JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Heat & Thermodynamics

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A Carnot engine operates between two reservoirs of temperatures 900 K and 300 K . The engine performs 1200 J of work per cycle. The heat energy (in J) delivered by the engine to the low temperature reservoir, in a cycle is ____.

Answer: 600

Solution

A Carnot engine between

900 K

and

300 K

has efficiency

η = 1 - \frac{T _{L}}{T _{H}} = 1 - \frac{300}{900} = \frac{2}{3}

. From

η = \frac{W}{Q _{H}}

the heat drawn from the hot reservoir is

Q_{H} = \frac{W}{η} = \frac{1200}{2/3} = 1800 J

, and energy conservation gives the heat rejected to the cold reservoir as

Q_{L} = Q_{H} - W = 1800 - 1200 = 600 J

JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Integer answer

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