If ' $\lambda_1$ ' and ' $\lambda_2$ ' are the wavelengths of the first member of the Balmer and Paschen series, in hydrogen atom respectively, then the ratio of respective frequencies, $f_1 / f_2$, is

The ratio of angular momentum $L$ of an electron to the magnetic dipole moment $\overrightarrow{\mathrm{m}}_{\text {orb }}$ is ( ' $m$ ' is mass of electron, ' $e$ ' is charge on electron)

Three samples $X, Y$, and $Z$ of same gas have equal volumes and temperatures. The volume of each sample is doubled, the process being isothermal for X , adiabatic for Y and isobaric for Z . If the final pressures are equal for the three samples, the ratio of the initial pressures is ( $\gamma=3$ / 2)

The self-inductance of a circuit is numerically equal to