Micrometres (pm) = 10-6 m Nanometres (nm) = 10-9 m
Example: Radiation of colour green: 1 = 550 nm = 0.55 pm
E(electron-volt, eV) = hv = —
where h is Planck’s constant, v is the frequency, c is the speed of light and 1 is the wavelength, or more simply E = 1.24/1 with E in eV and l in pm.
Example: Energy of photon with a wavelength of 550 nm: