Propaga tion of light quanta may be described by

The propagation of light quanta is described by photons. According to modern quantum theory, light exhibits a dual nature, behaving as both a wave and a stream of particles [c2]. These discrete 'energy-grains' or portions of energy are termed light quanta or photons [t1]. A photon is defined as the smallest possible particle of electromagnetic energy and the fundamental quantum of light [t5][t7]. While classical wave theory describes light propagation through fields, quantum mechanics identifies photons as the elementary excitations of the electromagnetic quantum field [t6]. Unlike protons, neutrons, or electrons, which are quanta of matter or electricity, photons are the specific quanta of radiation that travel at the speed of light in a vacuum [t1][t5]. This conceptualization reconciles particle-like interactions with wave-like propagation characteristics [c2][t9].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > p. 134
2. [2] https://www.energy.gov/science/doe-explainsphotons