Concepts Of Physics MCQ Edition [Volume 2]PhysicsPhotoelectric Effect and Wave–Particle Duality
In an experiment on the photoelectric effect, if the wavelength of the incident light is doubled,
Options
- Aphotoelectric emission may or may not occur
- Bthe stopping potential will increase
- Cthe stopping potential will decrease
- Dphotoelectric emission will not occur
Correct answer
C. the stopping potential will decrease
Step-by-step solution
According to Einstein's photoelectric equation, the maximum kinetic energy of emitted photoelectrons is given by K_ = hc - , where is the work function of the metal and V_s is the stopping potential such that K_ = eV_s . When the wavelength of the incident light is doubled, the new energy of the incident photon becomes E' = hc 2 = E 2 . If E 2 , photoelectric emission will continue. Thus, photoelectric emission may or may not occur. If emission continues, the new stopping potential V_s' is given by eV_s' = E 2 - =