Which of the following statements are correct?
A. Photoelectric current depends on the intensity of light.
B. The stopping potential is directly related to the maximum kinetic energy of electrons emitted which is dependent on the intensity of incident radiation.
C. Photoelectric emission from a metal surface occurs due to absorption of a photon by an electron.
D. Photoelectric effect follows the law of conservation of energy.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, C and D only
The photoelectric effect is explained by Einstein's photoelectric equation, \( K_{\max} = h\nu - \phi_0 \), in which one photon gives all its energy to one electron.
(A) Photoelectric current depends on the intensity of light. — Correct. For a fixed frequency above the threshold, a more intense beam has more photons per second, so more electrons are emitted per second and the photocurrent is larger.
(B) The stopping potential is directly related to the maximum kinetic energy of electrons emitted which is dependent on the intensity of incident radiation. — Incorrect. The stopping potential is related to the maximum kinetic energy, \( eV_0 = K_{\max} \), but \( K_{\max} \) depends on the frequency and the metal, not on the intensity.
(C) Photoelectric emission from a metal surface occurs due to absorption of a photon by an electron. — Correct. An electron absorbs one whole photon and escapes if \( h\nu \) is at least the work function.
(D) Photoelectric effect follows the law of conservation of energy. — Correct. The photon energy is shared between the work function and the kinetic energy of the electron, \( h\nu = \phi_0 + K_{\max} \).
NCERT (2026-27):
Summary – “… 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. 4. The stopping potential (Vo) depends on (i) the frequency of incident light, and (ii) the nature of the emitter material. For a given frequency of incident light, it is independent of its intensity.”
Summary – “… Photoelectric emission from the metal surface occurs due to absorption of a photon by an electron. 7. Einstein’s photoelectric equation is in accordance with the energy conservation law as applied to the photon absorption by an electron in the metal.”