When a certain metal is illuminated by light, photoelectrons are observed provided that the wavelength of the light is less than 669 nm. Which one of the following values is closest to the work function of this metal? (h = 6.626 × 10^-34 J ∙ s, c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J) A) 1.9 eV B) 2.0 eV C) 2.2 eV D) 2.3 eV

Question

Quizplus · Accepted Answer

The work function is given by the equation: hc/λ = Φ + KE, where hc/λ is the energy of the incident photon, Φ is the work function, and KE is the kinetic energy of the photoelectron. Since the photoelectrons are observed when the wavelength of the light is less than 669 nm, the energy of the incident photon is greater than the work function. Therefore, the work function must be less than the energy of the incident photon, which is hc/λ = (6.626 × 10^-34 J s)(3.00 × 10^8 m/s)/(669 × 10^-9 m) = 2.96 eV. The closest value to this is 2.0 eV.

When a Certain Metal Is Illuminated by Light, Photoelectrons Are