Q156 / 180 · COMEDK 2013 · Physics
Which of the following relations does not give the equation of an adiabatic process, where terms have their usual meaning?
- A$p^{1-\gamma} T^{\gamma}=$ constant
- B$p V^{\gamma}=$ constant
- C$T V^{\gamma-1}=$ constant
- Correct answerD$p^{\gamma} T^{1-\gamma}=\mathrm{constant}$
Solution
For adiabatic process,
$p V^{\gamma}=$ constant
For an ideal gas, $p V=n R T$ or $p=\frac{n R T}{V}$
Again, from ideal gas equation,
$$
\begin{aligned}
V &=\frac{n R T}{p} \\
\Rightarrow \quad p\left(\frac{n R T}{p}\right)^{\gamma} &=\text { constant } \\
\Rightarrow \quad p^{1-\gamma} T^{\gamma} &=\text { constant }
\end{aligned}
$$
Hence, relation shown in option (d) is not for adiabatic process.
Hence, the correct answer is option: 'D'.