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NEET 2015
Exam
NEET
Year
2015
Subject
Physics
Chapter
Thermodynamics

NEET 2015 · Physics · Thermodynamics

A Carnot engine, having an efficiency of η = (1)/(10) as heat...

A Carnot engine, having an efficiency of η=110η = \dfrac{1}{10} as heat engine, is used as a refrigerator. If the work done on the system is 10J10J, the amount of energy absorbed from the reservoir at a lower temperature is:

Options

  1. A100J100J
  2. B99J99J
  3. C90J90J
  4. D1J1J

Correct answer

C. 90J90J

Step-by-step solution

For engine and refrigeration operating between two same temperature, the relationship between efficiency and coefficient of performance β\beta,

η=11+βη = \dfrac{1}{1 + \beta}

110=11+β⇒β=9\dfrac{1}{10} = \dfrac{1}{1 + \beta} ⇒ \beta = 9

From the principle of the refrigerator, coefficient of performance is given by the ratio of the amount of energy absorbed from the reservoir to work, i.e.,

Q2W=β\dfrac{{Q}_{2}}{W} = \beta

Q210=9\dfrac{{Q}_{2}}{10} = 9

Q2=90J{Q}_{2} = 90J.

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