Photoelectric work function of a metal is 1 e V Light of wavelength λ =3000 Å falls on it, The photo-electrons come with velocity

hv=W+12mv2  or hcλ=W+12mv2  Here λ=3000Å=3000×10−10m and W=1eV=1.6×10−19 joule  6⋅6×10−343×1083000×10−10 =1⋅6×10−19+12×9⋅1×10−31v2 Solving, we get v=106m/s