Question

A magnesium surface has a work function of 3.60 eV. Electromagnetic waves with a wavelength of 320 nm strike the surface and eject electrons. Find the maximum kinetic energy of the ejected electrons. Express your answer in electron volts.

Answer 1

Answer:

K(maximum) = 0.284 eV

Explanation:

Given data

work function ω = 3.60 eV = 3.60 × 1.6 ×$10^{-19}$ = 5.76 ×$10^{-19}$ J

wavelength λ = 320 nm  = 320 ×$10^{-9}$ m

to find out

maximum kinetic energy

solution

we know that speed of light is =  3 ×$10^{8}$ m/s

and planck constant h = 6.63 ×$10^{-34}$ J.s

we will apply here Einstein's photo elecric equation that is

hc/λ  =  ω + K(maximum)

put here all these value we get

6.63 ×$10^{-34}$ ×  3 ×$10^{8}$  / 320 ×$10^{-9}$ =   5.76 ×$10^{-19}$  + K(maximum)

so

K(maximum) = 6.63 ×$10^{-34}$ ×  3 ×$10^{8}$  / 320 ×$10^{-9}$ - 5.76 ×$10^{-19}$

K(maximum) = 0.4556 ×$10^{-19}$  J

K(maximum) = 0.4556 ×$10^{-19}$  / 1.6  ×$10^{-19}$

K(maximum) = 0.284 eV