Concepts Of Physics MCQ Edition [Volume 2]PhysicsPhotoelectric Effect and Wave–Particle Duality
A light wave has an associated electric field given by E = E₀ ! [(1.57 10^7 m ⁻¹)(x - ct) ] . Determine the stopping potential if this light is utilized in a photoelectric effect experiment where the emitter possesses a work function of 1.9 eV .
Options
- A3.1 V
- B5.0 V
- C1.2 V
- D1.9 V
Correct answer
C. 1.2 V
Step-by-step solution
The given electric field is E = E₀ [(1.57 10^7 m ⁻¹)(x - ct)] . Comparing this with the standard wave equation E = E₀ [k(x - ct)] , the wave number is k = 1.57 10^7 m ⁻¹ . Since k = 2 , the wavelength is: = 2 1.57 10^7 = 2 3.14 1.57 10^7 = 4 10⁻⁷ m = 4000 The energy of the incident photon is: E = hc = 12400 eV 4000 = 3.1 eV From Einstein's photoelectric equation, the maximum kinetic energy K_ is: K_ = E - Substituting the given work function = 1.9 eV : K_ = 3.1 eV - 1.9 eV = 1.2 eV The stopping potential V₀ is give