In the hydrogen spectrum,the various lines of the Lyman series lie in the $.......$ region.

Calculate the frequency if the wavelength is $750 \ nm$.

Find the energy of radiation having $7000 \ \mathring{A}$ and $400 \ nm$ wavelength. $\left( h = 6.62 \times 10^{-34} \ J \ s, c = 3 \times 10^8 \ m/s \right)$

The wavelength of $X$-ray is $1.5 \times 10^{-10} \ m$. Find the frequency.

If $p$ is the momentum of the fastest electron ejected from a metal surface after the irradiation of light having wavelength $\lambda$,then for $1.5 \ p$ momentum of the photoelectron,the wavelength of the light should be: (Assume kinetic energy of ejected photoelectron to be very high in comparison to work function)

Calculate the energy of one mole of photons of radiation whose frequency is $5 \times 10^{14} \ Hz$.