Question

g Calculate the maximum wavelength of light that will cause the photoelectric effect for potassium. Potassium has work function 2.29 eV = 3.67 x 10–19 J.

Answer 1

Answer:

λ = 5.4196 10⁻⁷m,  λ = 541.96 nm    this is green ligh

Explanation:

The photoelectric effect was explained by Eintein assuming that the light was made up of particles called photons and these collided with the electrons taking them out of the material.

 

                     K = h f -Ф

where K is the kinetic energy of the ejected electrons, hf is the energy of the light quanta and fi is the work function of the material.

The speed of light is related to wavelength and frequency

                   c = λ / f

                  f = c /λ

we substitute

                K = h c / λ - Φ

for the case that they ask us the kinetic energy of the electons is zero (K = 0)

                 h c / λ = Ф

                λ = h c / Ф

we calculate

                 λ = 6.63 10⁻³⁴  3 10⁸ / 3.67 10⁻¹⁸

                 λ = 5.4196 10⁻⁷m

let's take nm

                lam = 541.96 nm

this is green light