Light of wavelength 200.0 nm is incident on a metal plate with a threshold wavelength of 400.0 nm. What is the energy of the incident photon in electron volts? a. 2.48 * 105 eV c. 6.20 eV b. 0.161 eV d. 3.10 eV

The energy possessed by a photon of a given wavelength is given by Planck's equation:

E = hc/λ, where E is the energy, h is the Planck's constant, c is the speed of light and λ is the wavelength of the photon. Substituting the values

E = (6.63 x 10⁻³⁴) (3 x 10⁸) / (200 x 10⁻⁹)

E = 1 x 10⁻¹⁸ Joules