Two open pipes of different lengths and same diameter in which the air column vibrates with fundamental frequencies ' $n_1$ ', and ' $n_2$ ' respectively. When both pipes are joined to form a single pipe, its fundamental frequency will be

If ' $C_P$ ' and ' $C_V$ ' are molar specific heats of an ideal gas at constant pressure and volume respectively. If ' $\lambda$ ' is the ratio of two specific heats and ' $R$ ' is universal gas constant then ' $C_p$ ' is equal to

In a series $L C R$ circuit $R=300 \Omega, L=0.9 \mathrm{H}$, $C=2 \mu \mathrm{~F}, \omega=1000 \mathrm{rad} / \mathrm{s}$. The impedance of the circuit is

The quantity which does not vary periodically for a particle performing SHM is