Easy MCQ +4 / -1 PYQ · JEE Mains 2021

For an adiabatic expansion of an ideal gas, the fractional change in its pressure is equal to (where $\gamma$ is the ratio of specific heats) :

  1. A $- {1 \over \gamma }{{dV} \over V}$
  2. B $- \gamma {V \over {dV}}$
  3. C $- \gamma {{dV} \over V}$ Correct answer
  4. D ${{dV} \over V}$

Solution

for adiabatic expansion :<br><br>PV<sup>$\gamma$</sup> = const.<br><br>$\Rightarrow$ ln P + $\gamma$ln v = const.<br><br>$\Rightarrow$ differentiating both sides;<br><br>${{dp} \over p} + \gamma {{dv} \over v} = 0$<br><br>$\Rightarrow {{dp} \over p} = - \gamma {{dv} \over V}$

About this question

Subject: Physics · Chapter: Thermodynamics · Topic: Zeroth and First Law

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