Let $\lambda_{e r} \lambda_p$ and $\lambda_d$ be the wavelengths associated with an electron, a proton and a deuteron, all moving with the same speed. Then the correct relation between them is

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

Which one of the following metals does not exhibit emission of electrons from its surface when irradiated by visible light?

The energy of a photon of wavelength $$\lambda%$ is