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Carnot Cycle and Efficiency

An engine operates on a Carnot cycle between a hot reservoir at \mathrm{600 K} and a cold reservoir at \mathrm{300 K}. Calculate the efficiency of the engine and the heat absorbed from the hot reservoir if it expels \mathrm{4000 J } of heat to the cold reservoir.
 

Option: 1

\mathrm{8000J}
 


Option: 2

\mathrm{4690 J}
 


Option: 3

\mathrm{2520 J}


Option: 4

\mathrm{1000J}


Answers (1)

best_answer

Given data:

Temperature of hot reservoir, \mathrm{T_h = 600 K}

Temperature of cold reservoir, \mathrm{T_c = 300 K}

Heat expelled to cold reservoir, \mathrm{Q_c = 4000 K}

The efficiency of a Carnot engine is given by the formula:

Efficiency \mathrm{=1-\frac{T_c}{T_h} }

Efficiency  \mathrm{=1-\frac{300 \mathrm{~K}}{600 \mathrm{~K}} }

Efficiency \mathrm{=0.5}

The heat absorbed from the hot reservoir can be calculated using the efficiency formula:

Efficiency \mathrm{=\frac{Q_h-Q_c}{Q_h}}

Where \mathrm{Q_h} is the heat absorbed from the hot reservoir.

Solving for \mathrm{Q_h :}

\mathrm{0.5 =\frac{Q_h-4000 \mathrm{~J}}{Q_h} }

\mathrm{0.5 Q_h =Q_h-4000 \mathrm{~J} }

\mathrm{0.5 Q_h =4000 \mathrm{~J} }

\mathrm{Q_h =8000 \mathrm{~J} }

Therefore,the correct option is 1





 

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