Question

Define the term 'threshold frequency' for a photosensitive material.

Why it is the frequency and not the intensity of light source that determines whether emission of photoelectrons will occur or not ? Explain.

A proton and an α particle are moving with the same speed. Which one of them has greater value of de Broglie wavelength associated with it ? Justify your answer.

Lights of wavelengths 430 nm, 450 nm and 660 nm are incident on a metal surface whose threshold wavelength is 600 nm. In which case/cases will photoemission take place and why ? Calculate the threshold frequency of the metal surface.