Calculate the kinetic energy of an electron ejected from a piece of sodium (Φ = 4.41x10–19 J) that is illuminated with 265 nm light. in Joules

Explanation:

Energy of falling radiation having wavelength of 265 nm

= h c / λ where h is plank's constant , c is velocity of light and λ is wavelength of radiation . Putting the values

Energy of light photon = 6.6 x 10⁻³⁴ x 3 x 10⁸ / 265 x 10⁻⁹

= .0747 x 10⁻¹⁷

= 7.47 x 10⁻¹⁹ J .

Work function of sodium is 4.41 x 10⁻¹⁹

So kinetic energy of ejected electron = energy of falling photon - work function

= 7.47 x 10⁻¹⁹ - 4.41 x 10⁻¹⁹

= 3.06 x 10⁻¹⁹ eV .