Which of the following are the properties of photons?
A. Each photon of frequency (ν) has energy E = hν
B. The energy of photons of light of a particular frequency increases, if the intensity of light increases.
C. Photons are electrically neutral and are not deflected by electric and magnetic fields.
D. The rest mass of the photon can not be zero.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A and C only
A photon is a quantum of electromagnetic radiation: it carries energy \( h\nu \) and momentum \( h/\lambda \), travels at speed c, and has no charge.
(A) Each photon of frequency (ν) has energy E = hν — Correct. The energy of a photon depends only on its frequency, through Planck’s constant.
(B) The energy of photons of light of a particular frequency increases, if the intensity of light increases. — Incorrect. A higher intensity means more photons crossing unit area per second; the energy of each photon is still \( h\nu \).
(C) Photons are electrically neutral and are not deflected by electric and magnetic fields. — Correct. A particle with no charge feels no electric or magnetic force.
(D) The rest mass of the photon can not be zero. — Incorrect. A photon always moves at c and has zero rest mass; its momentum comes from its energy, \( p = E/c \).
NCERT (2026-27):
Particle Nature of Light: The Photon – “… (ii) Each photon has energy \( E (= h\nu) \) and momentum \( p (= h\nu/c) \), and speed \( c \), the speed of light.”
Particle Nature of Light: The Photon – “… By increasing the intensity of light of given wavelength, there is only an increase in the number of photons per second crossing a given area, with each photon having the same energy. Thus, photon energy is independent of intensity of radiation.”
Particle Nature of Light: The Photon – “… (iv) Photons are electrically neutral and are not deflected by electric and magnetic fields.”