A photosensitive surface has work function $\phi$. If photon of energy $3 \phi$ falls on this surface, the electron comes out with maximum velocity of $4 \times 10^6 \mathrm{~m} / \mathrm{s}$ When photon energy is increased to $7 \phi$ then maximum velocity of photoelectron will be

Energy of the incident photons on the metal surface is initially 4 W and then 6 W where $W$ is the work function of that metal. The ratio of velocities of emitted photoelectrons is

Let $E_c$ and $E_p$ represents kinetic energy of electron and photon respectively. If de-Broglie wavelength of a photon is twice the de-Broglie wavelength of an electron then $E_p / E_c$ is (speed of electron $=\mathrm{C} / 100$ where C is the velocity of light)

The graph shows the variation of photocurrent with anode potential for four different radiations. Let $\mathrm{I}_{\mathrm{a}}, \mathrm{I}_{\mathrm{b}}, \mathrm{I}_{\mathrm{c}}$ and $\mathrm{I}_{\mathrm{d}}$ are intensities and $\mathrm{f}_{\mathrm{a}}, \mathrm{f}_{\mathrm{b}}, \mathrm{f}_{\mathrm{c}}$ and $\mathrm{f}_{\mathrm{d}}$ be the frequencies for the curves $\mathrm{a}, \mathrm{b}, \mathrm{c}$ and d respectively, then