A Monochromatic light of frequency $6.0\times {10}^{14} \mathrm{Hz}$ is produced by a laser. The power emitted is $2\times {10}^{–3} \mathrm{W}$. The number of photons emitted on the average by the source per second is,

The work function of a surface of a photosensitive material is $6.2 \text{eV}$. The wavelength of the incident radiation, for which the stopping potential is $5 \text{V}$, lies in the

The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement?

The electron in the hydrogen atom jumps from excited state $\left(n=3\right)$ to its ground state $\left(n=1\right)$ and the photons thus emitted irradiate a photosensitive material. If the work function of the material is $5.1 \mathrm{eV}$, the stopping potential is estimated to be,

(Energy of the electron in $n^{th} \text{state}, E_{\mathrm{n}}=-\frac{13.6}{{\mathrm{n}}^2} \mathrm{eV}$)