With reference to the observations in photo-electric effect, identify the correct statements from below:
A. The square of maximum velocity of photoelectrons varies linearly with frequency of incident light.
B. The value of saturation current increases on moving the source of light away from the metal surface.
C. The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (light emitting diode) source of light.
D. The immediate emission of photo-electrons out of metal surface can not be explained by particle nature of light/electromagnetic waves.
E. Existence of threshold wavelength can not be explained by wave nature of light/electromagnetic waves.
Choose the correct answer from the options given below:
Answer: (B) A and E only
A: True. $\dfrac12mv_{\max}^2 = h\nu - \phi$, so $v_{\max}^2$ is linear in $\nu$.
B: False. Moving the source away lowers the intensity, so the saturation current decreases.
C: False. The maximum kinetic energy depends on frequency, not on the power of the source.
D: False. Instant emission is exactly what the photon (particle) picture explains.
E: True. The wave picture cannot explain a threshold.
A and E only.
Solution by Sreeraj P, M.Sc Physics