Physics, asked by pallabroy, 1 year ago

The dielectric constant of water is 80, however its refractive index is 1 ·33 invalidating
the expression n*n=ε. This is because
(1) the water molecule has no permanent dipole moment
{2) the boiling point of water is 100 °C
(3) the two quantities arc measured by different experiments
(4) water is transparent to visible light
Which one is the correct option?

Answers

Answered by kvnmurty
19
(3)  the two quantities are measured by different experiments.
      Refractive index of 1.33 is for visible light..
       The refractive index for water for low frequencies is much higher .
      Dielectric constant of water is 80 for very low frequencies.  For very high frequencies it is around 1.66 to 1.7  or so.   So the relation matches for the same frequency.

     Dielectric constant reduces for very high frequency as the polarization or polarizability reduces at high frequencies. The medium cannot polarize light or waves falling on it so quickly for high frequency waves.

   relations:   c / v  = n  = refractive index
                    n = √[ ε_r μ_r  ]            
                     μ_r = relative magnetic permeability is nearly 1
                    so   n * n ≈ ε_r  or K = dielectric constant
                    c² = 1/[μ₀ ε₀]

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