Concepts Of Physics MCQ Edition [Volume 2]PhysicsPhotoelectric Effect and Wave–Particle Duality
For a photoelectric material with a work function of 4.0 eV , calculate the wavelength of incident light that results in a stopping potential of 2.5 V .
Options
- A496 nm
- B191 nm
- C310 nm
- D827 nm
Correct answer
B. 191 nm
Step-by-step solution
According to Einstein's photoelectric equation: E = + K_ Given work function = 4.0 eV and stopping potential V₀ = 2.5 V . The maximum kinetic energy of the photoelectrons is K_ = eV₀ = 2.5 eV . The energy of the incident photon is: E = 4.0 eV + 2.5 eV = 6.5 eV The wavelength of the incident light is given by = hc E . Using hc 1240 eV nm : = 1240 6.5 191 nm