Ultraviolet light of wavelength `2271Å` from a 100W mercury source irradiates a photocell made of molybdenum metal. If the stopping potential is 1.3V, estimate the work function of the metal. How would the photocell respond to a high intensity `(~10^(5)Wm^(-2))` red light of wave length `6328Å` produced by a He-Ne laser?

Explanation

`phi_(0)=hv-eV_(0)=6.7xx10^(-19)J=4.2eV,v_(0)=(phi_(0))/(h)=1.0xx10^(15)Hz, lambda=6328Å` corresponds to `v=4.7xx10^(14)Hz lt v_(0)`. The photo - cell will not respond howsoever high be the intensity of laster light.