Particle Nature of Light

Photoelectric effect gave evidence that light consists of packets of energy. These packet of energy is called light Quantum that are associated with particles named as photons. So photons confirm particle nature of light.


Characteristic Properties of Photons:


The following characteristic of photon which proves particle nature of light.

(I) In the interaction of radiation with matter, radiation behaves as if it is made up of particles called photons.

(II) Each Photon has energy(E= hv) and momentum(P= h/λ).

(III) All photons of light of particular frequency(v) or wavelength(λ) have the same energy and Momentum independent of the intensity of the radiation.

(IV) Photons are electrically neutral and are not detected by electric and magnetic fields.

(V) All Photon Travels at a speed of light(c) in vacuum.

(VI) Photos travel in straight line.

(VII) Wavelength of photons changes in different media, so velocity of a photon is different in different media.

(VIII) It has zero rest mass i.e. the photon cannot exist at rest.


(IX) The inertial mass of a photon is given by
        m= E/c²= h/cλ.


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