The second law of thermodynamics saysa)Coefficient of performance can never be infinite for refrigeratorb)Heat released to the cold reservoir can be zeroc)Ideal gas can expand infinitelyd)Efficiency of a heat engine can be 100%.Correct answer is option 'A'. Can you explain this answer?

Question

Answer

The second law of thermodynamics gives a fundamental limitation to the efficiency of a heat engine and the coefficient of performance of a refrigerator. It says that the efficiency of a heat engine can never be unity or 100%, this implies that the heat released to the cold reservoir can never be made zero.
For a refrigerator the second law says that the coefficient through performance can never be infinite, this implies that the external work can never be zero.

Answer

Answer

The Second Law of Thermodynamics:

The second law of thermodynamics is a fundamental principle in physics that governs the behavior of energy and heat transfer. It has several statements, but one of its key implications is that the coefficient of performance (COP) of a refrigerator or heat pump can never be infinite.

Understanding the Coefficient of Performance (COP):

The coefficient of performance (COP) is a measure of the efficiency of a refrigerator or heat pump. It is defined as the ratio of the desired output (cooling or heating) to the required input (work or energy). Mathematically, COP is given by:

COP = Desired Output / Required Input

For a refrigerator or heat pump, the desired output is the amount of heat transferred from the cold reservoir (the space being cooled) to the hot reservoir (the surroundings) per unit of work input. The required input is the amount of work or energy required to achieve this heat transfer.

The Second Law's Implication:

The second law of thermodynamics states that it is impossible to transfer heat from a colder object to a hotter object without the input of work or the use of a heat pump. In other words, heat naturally flows from objects at higher temperatures to objects at lower temperatures.

Explanation of Option 'A':

Option 'A' states that the coefficient of performance can never be infinite for a refrigerator. This is consistent with the second law of thermodynamics because a COP of infinity would imply that heat could be transferred from a cold reservoir (the space being cooled) to a hot reservoir (the surroundings) without any work input.

If the COP were infinite, it would mean that the refrigerator could continuously cool the space without any energy input. However, according to the second law, this is not possible. The refrigerator requires work input to transfer heat from the cold reservoir to the hot surroundings. Therefore, the COP can never be infinite.

Conclusion:

The second law of thermodynamics is a fundamental principle that governs the behavior of energy and heat transfer. It implies that the coefficient of performance (COP) of a refrigerator or heat pump can never be infinite. Option 'A' is the correct answer because it aligns with this implication of the second law.

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