Monochromatic light shines on a surface with work function 1.80 eV. The maximum energy of the emitted photoelectrons is 0.620 eV. What is the wavelength of the monochromatic light?
A) 200 nm
B) 290 nm
C) 689 nm
D) 602 nm
E) 512 nm

Question

Quizplus · Accepted Answer

The energy of the incident light is the sum of the work function and the maximum kinetic energy of the photoelectrons. Using the equation E = hf = hc/λ, where h is Planck's constant and c is the speed of light, we find the wavelength λ. The energy of the incident light is 1.80 eV + 0.620 eV = 2.42 eV. Converting this energy to joules and using hc = 1240 eV·nm, we find λ = 1240 eV·nm / 2.42 eV ≈ 512 nm.

Monochromatic Light Shines on a Surface with Work Function 1