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where , μ o = absolute magnetic permeability and ε o = absolute electrical permittivity of free space .
( vi ) It failed to explain the phenomenon of photoelectric effect , Compton effect and Raman effect .
Max Planck ’ s Quantum Theory
( i ) Light emits from a source in the form of packets of energy called quanta or photon .
( ii ) The energy of a photon is E == hv , where h is Planck ’ s constant and v is the frequency of light .
( iii ) Quantum theory could explain photoelectric effect , Compton effect and Raman effect . ( iii ) Quantum theory failed to explain interference , diffraction and polarisation of light .
de – Broglie ’ s Dual Theory
Light waves have dual nature , wave nature according to Maxwell ’ s electromagnetic wave theory and particle nature according to Max-Planck ’ s quantum theory .
Two natures of light are like the two faces of a coin . In anyone phenomena only its one nature appears .
Energy of photon = hv = hc / λ where , h = Planck ’ s constant 6.6 * 10 < sup-34 J / s
de-Broglie wave equation is λ = h / p = h / mv where h denotes Planck ’ s constant .
Superposition of Waves
When two similar waves propagate in a medium simultaneously , then at any point the resultant displacement is equal to the vector sum of displacement produced by individual waves .
y = y 1 + y 2
Interference of Light
When two light waves of similar frequency having a zero or constant phase difference propagate in a medium simultaneously in the same direction , then due to their superposition maximum intensity is obtained at few points and minimum intensity at other few points .
This phenomena of redistribution of energy due to superposition of waves is called interference of light waves .