In the figure shown electromagnetic radiations of wavelength 200 nm are incident on the metallic plate A. The photo electrons are accelerated by a potential difference 10 V. These electrons strike another metal plate B from which electromagnetic radiations are emitted. The minimum wavelength of the emitted photons is 100 nm. If the work function of the metal 'A' is found to be 1.9 N eV. The value of N is

$\text{ Use }hv=12400\mathrm{eV}\text{Å, use }R\text{ ch }-13.6\mathrm{eV}\text{. }$