Question

Light with a frequency of 3.70 × 1015 Hz strikes a metal surface and ejects electrons that have a maximum kinetic energy of 5.4 eV. What is the work function of the metal?

Answer 1

What is the work function of a metal?

Using a formula, we have

K.E_max = h f -

where, h = planck constant = 6.63 x 10^-34 J.s

f = frequency of light = 3.70 x 10¹⁵ Hz

K.E_max = maximum kinetic energy = 5.4 eV = 8.6518 x 10^-19 J

then, we get

(8.6518 x 10^-19 J) = [(6.63 x 10^-34 J.s) (3.70 x 10¹⁵ Hz)] -

= [(2.4531 x 10^-18 J) - (8.6518 x 10^-19 J)]

= 1.58792 x 10^-18 J

Converting J into eV :

= [(1.58792 x 10^-18 J) (6.241509 x 10¹⁸ eV/J)]

= 9.91 eV