Threshold frequency of a certain metal for photoelectric emission is 5 × 10 14 Hz . Calculate its work function.

Threshold frequency is the minimum frequency of the incident radiation required to eject photo electron from the surface of the metal The work function is the work to be done (energy required) to eject the electron, which are related with the equation W = E = hν where h = Planck's constant and ν = frequency Putting the required values, we have Work function W = h v 0 = 6 .6 × 10 − 34 Js × 5 × 10 14 s − 1 = 3 .3 × 10 − 19 J = 3 .3 × 10 − 19 J 1 .6 × 10 − 19 J / e V = 2 . 06 e V

Threshold frequency of a certain metal for photoelectric emission is 5 × 10 14 Hz . Calculate its work function.

Threshold frequency is the minimum frequency of the incident radiation required to eject photo electron from the surface of the metal The work function is the work to be done (energy required) to eject the electron, which are related with the equation W = E = hν where h = Planck's constant and ν = frequency Putting the required values, we have Work function W = h v 0 = 6 .6 × 10 − 34 Js × 5 × 10 14 s − 1 = 3 .3 × 10 − 19 J = 3 .3 × 10 − 19 J 1 .6 × 10 − 19 J / e V = 2 . 06 e V

The photoelectric threshold wavelength for sodium is 6800 A o . Explain its meaning.

According to the Einstein's explanation of the photo electric effect, a certain minimum energy (minimum frequency or maximum wavelength) is required to eject electron from the surface of a metal.If the wavelength of the incident radiation is more than this value, no photo electric effect is possible. This wave length is called the threshold wave length of the metal. Therefore, if the threshold wavelength is 6800 ° A , it means that to get photo electric effect, the wave length of incident light must be less than this value.