Monochromatic light source of power 5mW emits 8 x 1015 photons per second. This light ejects photoelectrons from a metal surface. The stopping potential for this setup is 2V. Calculate the work function of the metal.
a) 4.88 eV
b) 3.76 eV
c) 2.56 eV
d) 1.94 eV