A metallic surface is illuminated alternatively with light of wavelength 3000 A and 6000 A respectively. It is observed that the maximum speeds of the photoelectrons under these illuminations are in the ratio $$3 : 1$$ . Calculate the work function of the surface in $$\mathrm { eV } . \left( \mathrm { h } = 6.62 \times 10 ^ { - 34 } \mathrm { J } - \mathrm { s } , \mathrm { c } = 3 \times 10 ^ { 8 } \mathrm { m } / \mathrm { s } \right)$$