Read the following passage carefully:

Photoelectric effect is the phenomenon of emission of electrons from a metal surface, when radiations of suitable frequency fall on them. The emitted electrons are called photoelectrons and the current so produced is called photoelectric current.

Attempt the following questions based on the passage:

A point source of light of power 3$3.2\times {10}^{-3} \mathrm{W}$ emits monoenergetic photons of energy $5.0 \mathrm{eV}$ and work function $3.0 \mathrm{eV}$. The efficiency of photoelectron emission is 1 for every ${10}^6$ incident photons. Assume that photoelectrons are instantaneously swept away after emission. The maximum kinetic energy of photon is