The ionization energy of an electron in an excited state of a hydrogen atom is $+0.85 \, eV$. What will be the energy of the emitted photon in $eV$ when it returns to the ground state?

Neon gas is generally used in sign boards. If it emits strongly at $616 \, nm$,calculate $(a)$ the frequency of emission,$(b)$ distance traveled by this radiation in $30 \, s$,$(c)$ energy of a quantum,and $(d)$ number of quanta present if it produces $2 \, J$ of energy.

The energy difference of two stable orbits of Hydrogen is $214.68 \ kJ \ mol^{-1}$. If the transition of an electron takes place,find the emitted frequency. (Note: $v = \Delta E/h$ and $h = 6.626 \times 10^{-34} \ J \ s$)

Electrons with a kinetic energy of $6.023 \times 10^4 \ J/mol$ are evolved from the surface of a metal when it is exposed to radiation of wavelength $600 \ nm$. The minimum amount of energy required to remove an electron from the metal atom is

The work function $(W_0)$ of $Li, K, Mg, Ag$ and $Cu$ are $2.42, 2.25, 3.70, 4.30$ and $4.80 \ eV$ respectively. The number of metals which undergo photoelectric effect if a radiation of wavelength $540 \ nm$ falls on them is $(1 \ eV = 1.602 \times 10^{-19} \ J)$.

If the velocity of the revolving electron of $He^{+}$ in the first orbit $(n=1)$ is $v$,what is the velocity of the electron in the second orbit $(n=2)$?