Threshold wavelength of radiation
(λo) = 6800 × 10-10 m Or 6.8 × 10-7
Threshold frequency of the metal (vo) = c/λo
= (3 × 108)/(6.8 × 10-7)
vo = 441 × 1014 s-1
Now,
work function (Wo) of the metal = hvo
= (6.626 × 10-34 JS)(441 × 1014S-1)
= 2.922 × 10-19 J