# NEET Physics Thermodynamics Questions Solved

A monoatomic ideal gas, initially at temperature T1, is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature T2 by releasing the piston suddenly. If L1 and L2 are the lengths of the gas column before and after expansion respectively, then T1/ T2 is given by -

(1) ${\left(\frac{{L}_{1}}{{L}_{2}}\right)}^{2/3}$

(2) $\frac{{L}_{1}}{{L}_{2}}$

(3) $\frac{{L}_{2}}{{L}_{1}}$

(4) ${\left(\frac{{L}_{2}}{{L}_{1}}\right)}^{2/3}$

(4) ${T}_{1}{{V}_{1}}^{\gamma -1}={T}_{2}{{V}_{2}}^{\gamma -1}$

$⇒\frac{{T}_{1}}{{T}_{2}}={\left(\frac{{V}_{2}}{{V}_{1}}\right)}^{\text{\hspace{0.17em}}\gamma -1}$$={\left(\frac{{L}_{2}A}{{L}_{1}A}\right)}^{ \frac{5}{3}-1}={\left(\frac{{L}_{2}}{{L}_{1}}\right)}^{ \frac{2}{3}}$

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