The light is the set of packets of photons and as per the Einstien when light incident on a matter the electron-emitting process starts. As per the Max Plank, the radiation of the spectrum takes place due to the oscillation of atoms in the hot body or black body. Does the spectrum generate due to different energy levels either in the different energy levels of photons or the different energy levels in the matter that hit with light ??? Does the spectrum generate due to the particular shape of drops or prism ?? If the photons of different energy levels then why not events of the spectrum take place when the light hits any material. As we know by the concept of light when hit to a particular matter the color of material visible as per the material property.
Refraction in a prism or water drop cannot be suitably understood in the photon picture. Refraction is related to the phase velocity of light in glass or water, and this velocity varies with wavelength. It can be shown that the light path always follows the shortest possible path through the medium. This is known as Fermat's principle. From this principle, you can derive Snell's law. Knowing the wavelength dependence of the phase velocity, you can then calculate the angular dispersion of a prism etc. I recommend reading the relevant chapters in the optics textbook by Eugene Hecht.
Dear Guenter ,
Thanks to reply , There are many things come out through your answer.
When light or set of photons enter from one medium to another medium then refraction or dispersion of light takes place .There are things to consider
(i) frequency ( frequency of photons )
(ii) wavelength ( when frequency increase then wavelength decreases)
(iii) velocity (speed of light ) ( velocity change in different medium )
(iv) refractive index of material ( material of prism or medium does matter )
(v) Shape of Prism and water drop ( shape of prism or water also matter )
dear Vivek Kumar Sharma
when dealing with visible light Reflected or Refracted from a surface or a prism (or drop), the only realm that must be invoked to understand the ourcoming spectrum is that of traditional optics (light is considered as a EM wave). The only reason to sometimes include a pfoton-like effect is when a part of the incoming optical spectrum is absorbed by the material without any radiative re-emission or with very narrow lambda-range emission (as in the case of photoluminescence).
in the cases of a (high-purity) glass prism or water droplrt, no such absorption/radiative re-emission takes place, and you can safely describe the observed Reflected o Refracted spectra through standard physical optics, as suggested by Guenter Steinmeyer .
Therefore, I suggest you to forget for the case of interest:
- any photon description, and in particular photoelectric mechanism (what you called Einstein): even in metals, where a large density of free-electrons is available in the conduction band, you need at least an amount of energy larger than about 1 eV to promote the material free electron emission after a photon hits it (that is the well known Work Function, which means that visible lambda photons are not sufficient to produce a photoelectron leaving the material... you need near-UV photons at least).
- any black-body radiation source, which relies to a light )photons) emission from a material because of temperature... nothing to do with incoming light beams.At room temperature (300 K) the black body emission peak is around 9.6 micrometer (Wien's law) and the spectrum quickly falls down for smaller wavelenghts. Only heat (IR) is emitted at our common temperatures... any visible light.
@Vivek Kumar Sharma
Read refraction & Disperson from any book on optics : B.S.Matur old but gold .
There are a lot of questions around the questions
Physical optics Vs Quantum Optics
Light as EM wave or Particle of Photons
EM waves Vs Electromagnetic Field
Electromagnetic spectrum Vs Light
Wave Vs Particle
Invisible waves or Visible light
Electromagnetic Radiation Vs Electromagnetic Spectrum
The research starts when we analyse something and observe something in different way by others that already have written in many books and research paper.
@Vivek Kumar Sharma
In a prism/ water drop ,the wave characteristic dominates not particle nature.
Read Morden Physics, A.Beiser
How to generate a wave or electromagnetic wave?
Is the electromagnetic wave generated in space?
is the electromagnetic wave series of particles?
When an electromagnetic wave enters in particular material it loses the consideration as a series of particles?
As a very general rule, you will exclusively see the wave character of electromagnetic waves at low frequencies (radio waves, microwaves) and an increasing particle character at higher frequencies (gamma radiation, Compton scattering). Optics (visible wavelengths) is kind of in between, with some experiments requiring the wave picture for explanation, others the particle picture. The latter always comes into play when light is either detected or generated (photo effect, laser, blackbody radiation, Schawlow-Townes noise, shot noise). Nearly everything else can be best understood in the wave picture, including refraction, Snell's law, Fresnel reflection etc. as in your original question.
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