Which relation exactly describes the isothermal process?

Correct answer: A. Q = W

  • A. Q = W
  • B. W = -U
  • C. Q = -ΔU
  • D. Q = ΔU + W

Explanation

An isothermal process is a thermodynamic process in which the temperature of a system remains constant. The transfer of heat into or out of the system happens so slowly that thermal equilibrium is maintained. In an isothermal process, T = 0. If T = 0, then we can say that U = 0. According to the 1st law of thermodynamics, Q = U+W. In this case, the first law can be written as Q=W

This question appeared on the UHS MDCAT 2016 paper, which you can sit online with every answer explained.

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About First Law of Thermodynamics

The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.

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