Structure of Atom

What is the work function of the metal if the light of wavelength 4000$$\mathop A\limits^ \circ$$ generates photoelectrons of velocity 6 $$\times$$ 10⁵ ms^–1 from it ? (Mass of electron = 9 $$\times$$ 10^–31 kg; Velocity of light = 3 $$\times$$ 10⁸ ms^$$-$$1 Plank's constant = 6.626 $$\times$$ 10^–34 Js; Charge of electron = 1.6 $$\times$$10^–19 JeV^–1)