Optical pumping means transferring electrons:

Q. The life time of an excited state in case of metastable state is

Q. The condition for achieving laser action are
(i) the system must be in a state of population inversion
(ii) the excited state of the system should be in metastable state
(iii) the atom should be in lower energy state
(iv) no conditions required

Q. Laser light is generated by energizing Helium-Neon gas in chamber. The ground and metastable states of Helium are $0\text{eV}$ and $20.61\text{eV}$ respectively. The ground, higher and metastable energies of Neon are $0\text{eV}$, $18.70\text{eV}$ and $20.66\text{eV}$ respectively. The values of speed of light, Planck constant and charge of electron are $3\times {10}^8\text{m/s}$, $6.625\times {10}^{-34}\text{Js}$ and $1.6\times {10}^{-19}C$ respectively.
In this process, helium molecules

Q. Laser light is generated by energizing Helium-Neon gas in chamber. The ground and metastable states of Helium are $0\text{eV}$ and $20.61\text{eV}$ respectively. The ground, higher and metastable energies of Neon are $0\text{eV}$, $18.70\text{eV}$ and $20.66\text{eV}$ respectively. The values of speed of light, Planck constant and charge of electron are $3\times {10}^8\text{m/s}$, $6.625\times {10}^{-34}\text{Js}$ and $1.6\times {10}^{-19}C$ respectively.
Wavelength of laser light generated in this process is

Q. An electron collides with a free molecule initially in its ground state. The collision leaves the molecule in an excited state that is metastable and does not decay to the ground state by radiation. Let $K$ be the sum of the initial kinetic energies of the electron and the molecule, the $\overrightarrow{P}$ the sum of their initial momenta. Let $K^{\prime }$ and $\overrightarrow{P}$, represent the same physical quantities after the collision. Then.