The work function for a metal is $4 \, eV$. To emit a photo electron of zero velocity from the surface of the metal,the wavelength of incident light should be : ................ $\mathring{A}$

The ionisation energy of a certain element is $1540 \ kJ \ mol^{-1}$. When the atoms of this element are in the first excited state,the ionisation energy is only $300 \ kJ \ mol^{-1}$. Determine the region of the electromagnetic wave spectrum in which the light is emitted during a transition from the first excited state to the ground state.

The frequency of radiation emitted when the electron falls from $n = 4$ to $n = 1$ in a hydrogen atom will be (Given ionization energy of $H = 2.18 \times 10^{-18} \ J \ atom^{-1}$ and $h = 6.625 \times 10^{-34} \ Js$)

The total energy of the electron in the hydrogen atom in the ground state is $-13.6 \, eV$. What is the stopping potential in volts required to remove this electron from the ground state?

Explain linear and angular momentum.

The ionization energy of a $H$ atom is $13.6 \, eV$. The energy required to excite the electron from the ground state $(n=1)$ to the first excited state $(n=2)$ is ... $eV$.