List of top Physics Questions on Photoelectric Effect asked in BHU UET

An oxide coated filament is useful in vacuum tubes because essentially

A charged dust particle of radius $ 5\times {{10}^{-7}}m $ is located in a horizontal electric field having an intensity of $ 6.28\times {{10}^{5}}V{{m}^{-1}} $ . The surrounding medium is air with coefficient of viscosity $ \eta =1.6\times {{10}^{-5}}N-s{{m}^{-2}} $ . If this particle moves with a uniform horizontal speed $ 0.02\,m{{s}^{-1}} $ . Find the number of electrons on it.

Ultraviolet light wavelength $300 \,nm$ and intensity $1.0 \,Wm ^{-2}$ falls on the surface of a photoelectric material. If one percent of the incident photons produce photoelectrons, then the number of photoelectrons emitted per second from an area of $1.0 \,cm ^{2}$ of the surface is nearly