A monochromatic light is incident on the surface of a metal with work function W = 2.2 eV.
If a stopping potential V = - 2 V is required to make the photocurrent zero, what is the wavelength of light in nm?
1 nm = 10-9 m
h = 6.63 ×10-34 J·s
c = 3.0 ×108 ms-1
e = - 1.6 ×10-19 C
1 eV = 1.6 ×10-19 J