Question

What is the time lag between the incidence of photons and the ejection of photoelectrons?

(a) Greater than 10^-5 s

(b) Between 10^-5 s and 10^-9 s

(c) Less than 10^-9 s

(d) 1 second

The question was posed to me by my college director while I was bunking the class.

My query is from PhotoElectric Effect in portion Quantum Physics of Engineering Physics I

Answer 1

Correct choice is (c) Less than 10^-9 s

To elaborate: The laws of photoelectric emission states that it is an instantaneous process because the photoelectric emission occurs due to the elastic collision between a photon and an electron. Practically, there is no time lag (< 10^-9 s) between the incident photon and emission of an electron.