Electromagnetic radiation of 8.12×10¹⁸ hz frequency is applied on a metal surface and caused electron emission. determine the work function of the metal if the maximum kinetic energy () of the emitted electron is 4.16×10⁻¹⁷ j.

The work function ϕ of the metal = 53.4196 x 10⁻¹⁶ J      

Explanation:

When light is incident on a photoelectric material like metal, photoelectrons are emitted from the surface of the metal. This process is called photoelectric effect.

The relationship between the maximum kinetic energy () of the photoelectrons to the frequency of the absorbed photons (f) and the threshold frequency (f₀) of the photoemissive metal surface is:

                                        = h(f − f₀)

                                        = hf - hf₀

E is the energy of the absorbed photons:  E = hf

ϕ is the work function of the surface:  ϕ = hf₀

                                        = E - ϕ

Frequency f = 8.12×10¹⁸ Hz

Maximum kinetic energy = 4.16×10⁻¹⁷ J  

Speed of light  c = 3 x 10⁸ m/s

Planck's constant h = 6.63 × 10⁻³⁴ Js                                

                                        E = hf = 6.63 × 10⁻³⁴ x 8.12×10¹⁸

                                        E = 53.8356 x 10⁻¹⁶ J

from = E - ϕ ;

                                        ϕ = E -

                                        ϕ = 53.8356 x 10⁻¹⁶ - 4.16×10⁻¹⁷

                                        ϕ = 53.4196 x 10⁻¹⁶ J

The work function of the metal ϕ = 53.4196 x 10⁻¹⁶ J      

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray