Question

The work function of a metal is 1.6 x 10^-19 J. When the metal surface is illuminated by the light of wavelength 6400 Å, then the maximum kinetic energy of emitted photo-electrons will be (Planck's constant h = 6.4 x 10^-34 Js) ____________.

Options

• 14 x 10^-19 J

• 2.8 x 10^-19 J

• 1.4 x 10^-19 J

• 1.4 x 10^-19 eV

Answer 1

1.4 x 10^-19 J

Explanation:

`"K.E" = "hc"/lambda - phi`

`= (6.4 xx 10^-34 xx 3 xx 10^8)/(6400 xx 10^-10) - 1.6 xx 10^-19`

`= 1.4 xx 10^-19  "J"`