Question

The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency, ν0. Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 2.05 × 1014 s–1.

With what maximum kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of λ = 265 nm?

Answer 1

minium energy needed = hvo = (6.625 x10^-34) x (2.05 x 10^14)

                                     Eo = 1.358 x10^-19 J

λ = 265 nm

E = hC / λ = (6.625 x 10^-34) x(3x10^8) / 265 x 10^-9

E = 7.50 x10^-19 J

E = Eo + KE

7.50 x 10^-19 = 1.358 x10^-19 + KE

KE = 6.14 x 10^-19 J

kinetic energy = 6.14 x 10^-19 J