The variation of the stopping potential $\left(\mathrm{V}_0\right)$ with the frequency $(v)$ of the incident radiation for four metals A, B, C and D is shown in the figure. For the same frequency of incident radiation producing photo-electrons in all metals, the kinetic energy of photo-electrons will be maximum for metal

The energy of an electron in the ground state of hydrogen atom is -13.6 eV . The kinetic and potential energy of the electron in the first excited state will be

A Young's double-slit experimental set up is kept in a medium of refractive index $\left(\frac{4}{3}\right)$. Which maximum in this case will coincide with the $6^{\text {th }}$ maximum obtained if the medium is replaced by air?

The potential energy between two nucleon's inside a nucleus is minimum at a distance of about