Photoelectrons with a maximum kinetic energy of 7.95 eV are emitted from a metal when it is illuminated by ultraviolet radiation with a wavelength of 1.25 × 10-7 m. (i) Calculate the energy of the incident photons in electronvolts. (ii) Calculate the wavelength of the radiation (in nanometres) corresponding to the lowest energy photons that can free electrons from the metal. (iii) How do you explain the fact that, when infrared radiation is shone on this metal, no photoelectrons are emitted?

Ex1 / The minimum wave length for photoelectric emission in tungsten is 230nm. What wave length must be used in order to emit an electron with a maximum energy of 1.5 eV? Ex4/ the wave length of light falling on a potassium surface is 770nm and the work function of a potassium is equal to 2.3eV. show the photoelectric effect happening is possible or impossible? Ex5/The wavelength of the photoelectric threshold for silver is 3.250 x10- m. Determine the velocity of electron ejected from a silver surface by ultraviolet of wavelognnessletarandi

Calculate the energy associated with a photon of wavelength 4500 A .

The mathematical equation for studying the photoelectric effect is  hν = W + 1/2 meu2 where ν is the frequency of light shining on the metal; W is the energy needed to remove an electron from the metal; and me and u are the mass and speed of the ejected electron, respectively. In an experiment, a student found that a maximum wavelength of 351 nm is needed to just dislodge electrons from a metal surface. Calculate the velocity (in m/s) of an ejected electron when the student employed light with a wavelength of 283 nm.