A photoemissive substance is illuminated with a radiation of wavelength \( \lambda_i \) so that it releases electrons with de-Broglie wavelength \( \lambda_e \). The longest wavelength of radiation that can emit photoelectron is \( \lambda_0 \). Expression for de-Broglie wavelength is given by:
(\( m \) : mass of the electron, \( h \) : Planck’s constant and \( c \) : speed of light)
