Photon Passing Through Water

Absorption of a photon does launch an acoustic wave in water, but only at the point where it is absorbed or scattered. Photons in, e.g., a laser beam passing through water, are absorbed at points more or less randomly distributed along the beam's path. Absorption causes local heating, which causes local expansion, which causes the acoustic wave.

Systems using the photoacoustic effect make use of that acoustic wave. A very brief (nanoseconds) laser pulse can be launched in a thin sheet or line through a liquid solution, and spectral & phase analysis of the resulting acoustic signal provides clues re the dynamics of absorption and relaxation.


When a light is passed through water why doesn't it forms ripples?(like a stone does) I am assuming light is particle here. Photon mass ≠ 0

Photons always have zero mass and move with velocity c

when it's in motion It also have very high momentum

Its momentum depends on the frequency of the light beam to which it belongs. $E=hν$, and since the photon's mass is zero , $E=pc$

Light of frequency $ν$ emerges from the superposition of zillions of photons of energy $E=hν$, they are the building blocks of light, but an individual photon is an elementary particle , not light.

An individual photon passing through water can 1) scatter elastically, 2) scatter inelastically 3) if its frequency coincides with an energy level of the atoms or molecules, it can be absorbed completely. It cannot create waves in the water.

S.McGrew has given an answer for coherent light hitting the water.

Incoherent light just heats up the water due to absorption and inelastic scatters of the individual photons. Transparency in the water means that most of the photons scatter elastically with the medium, keeping their frequency and the images they build up.