Which of the following statements are correct?
A. Photo electric current does not depend on the nature of the emitter material.
B. Photo electric effect is an instantaneous process.
C. The stopping potential is directly related to the maximum kinetic energy of electrons emitted.
D. Energy required for the electron emission from the metal should be less than the work function.
E. The dualism of matter is inherent in the de Broglie relation.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → B, C and E Only
In the photoelectric effect, light of frequency above the threshold frequency ejects electrons from a metal surface; the work function \( \phi_0 \) is the least energy an electron needs to escape.
(A) Photo electric current does not depend on the nature of the emitter material. — Incorrect. The work function and the threshold frequency are properties of the emitter. Light that ejects electrons from one metal may give no current at all from another, so the current depends on the material.
(B) Photo electric effect is an instantaneous process. — Correct. Emission starts as soon as the light falls on the surface (within about \( 10^{-9}\,\mathrm{s} \)), even for very faint light.
(C) The stopping potential is directly related to the maximum kinetic energy of electrons emitted. — Correct. The stopping potential just stops the fastest electrons, so \( eV_0 = K_{\mathrm{max}} \).
(D) Energy required for the electron emission from the metal should be less than the work function. — Incorrect. The energy given to the electron must be at least equal to the work function; with less energy the electron cannot escape.
(E) The dualism of matter is inherent in the de Broglie relation. — Correct. In \( \lambda = h/p \) the wavelength is a wave property and the momentum a particle property, so the relation joins both pictures.
NCERT (2026-27):
Summary – “… 1. The minimum energy needed by an electron to come out from a metal surface is called the work function of the metal.”
Summary – “… The photoelectric emission is an instantaneous process and possesses certain special features.
3. Photoelectric current depends on (i) the intensity of incident light, (ii) the potential difference applied between the two electrodes, and (iii) the nature of the emitter material.”
Summary – “… The stopping potential is directly related to the maximum kinetic energy of electrons emitted: \( eV_0 = (1/2)\,m v_{\max}^2 = K_{\max} \).”
Summary – “… The dualism of matter is inherent in the de Broglie relation which contains a wave concept (\( \lambda \)) and a particle concept (p).”