A photoemissive substance is illuminated with a radiation of wavelength λ_i so that it releases electrons with de-Broglie wavelength λ_e. The longest…

A photoemissive substance is illuminated with a radiation of wavelength $\displaystyle \lambda_i$ so that it releases electrons with de-Broglie wavelength $\displaystyle \lambda_{\mathrm{e}}$. The longest wavelength of radiation that can emit photoelectron is $\displaystyle \lambda_{\mathrm{o}}$. Expression for de-Broglie wavelength is given by : (m : mass of the electron, h : Planck's constant and c : speed of light)