For a photosensitive material, work function is ' $\mathrm{W}_0$ ' and stopping potential is ' V '. The wavelength of incident radiation is ( $\mathrm{h}=$ Planck's constant, $c=$ velocity of light, $e=$ electronic charge)

The graph of stopping potential ' $\mathrm{V}_{\mathrm{s}}$ ' against frequency ' $v$ ' of incident radiation is plotted for two different metals ' X ' and ' Y ' as shown in graph. ' $\phi_x$ ' and ' $\phi_y$ ' are work functions of ' $x$ ' and ' $Y$ ' respectively then

The frequency of incident light falling on a photosensitive material is doubled, the K.E. of the emitted photoelectrons will be

When the electron orbiting in hydrogen atom in its ground state moves to the third excited state, the de-Broglie wavelength associated with it