Photoelectric Effect Questions

The time taken by a photoelectron to come out after the photon strikes is approximately:

The threshold frequency for a metallic surface corresponds to an energy of $6.2\text{eV}$, and the stopping potential for a radiation incident on this surface is $5\text{V}$. The incident radiation lies in the:

The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current $I$ of the photocell varies as follows: