Q. Which one of the following statements regarding photo-emission of electrons is correct?
A) Kinetic energy of electrons increases with the intensity of incident light.
B) Electrons are emitted when the wavelength of the incident light is above a certain threshold wavelength.
C) Photoelectric emission is instantaneous with the incidence of light.
D) Photoelectrons are emitted whenever a gas is irradiated with ultraviolet light.
Explanation
(c) KE of photoelectrons increases with increase in frequency of the incident light and is independent of the intensity of incident light.
Photoelectrons are emitted if the wavelength of the incident light is less than threshold wavelength, as $\phi_{0} = \frac{hc}{\lambda_{0}}$
Photoelectric emission is an instantaneous process photoelectrons may not be emitted from a gas with ultraviolet light if the work function of that gas is large than the energy UV light
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.