Photoelectric Effect

A charged dust particle of radius is located in a horizontal electric field having an intensity of . The surrounding medium is air with coefficient of viscosity . If this particle moves with a uniform horizontal speed . Find the number of electrons on it.

Ultraviolet light wavelength and intensity 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 of the surface is nearly

An oxide coated filament is useful in vacuum tubes because essentially