Refractive index of a material follows the Cauchy Dispersion formula.
Again, refractive index is square root of DIELECTRIC CONSTANT.
BUT, FOR WATER , DIELECTRIC CONSTANT IS 81, BUT REFRACTIVE INDEX IS NOT SQUARE ROOT OF 81, rather 1.33.
Please help me to understand this relationship between Cauchy Dispersion formula, DIELECTRIC CONSTANT and REFRACTIVE INDEX.
REGARDS
N DAS
For dielectrics it is correct that the index of refraction is equal to the square root of the dielectric constant, but the two values you mention are for two entirely different frequency bands. For frequencies below 100 MHz the dielectric constant is 81. The index of refraction of 1.33 you mention is for the visible region (~0.6 THz) where the dielectric constant is 1.76
Starting Points:
https://www.quora.com/How-is-the-dielectric-constant-related-to-the-index-of-refraction?share=1
https://www.scribd.com/document/225581243/Dispersion-Model
https://www.reading.ac.uk/infrared/library/absorptiontheory/ir-absorptiontheory-dielectricdispersion.aspx
Respected Sir, Kornfield
Thank you for your valuable answer.
Regards
N Das
Article Water: Promising Opportunities For Tunable All-dielectric El...
This article might help and indicates the frequency dependency of the dielectric constant of water (Figure 1) and how this figure greatly reduces when you reach optical frequencies. This results from the different EM wave interaction mechanisms that take place with water, i.e. transitioning from dipolar molecular polarization to atomic interactions.
For dielectrics it is correct that the index of refraction is equal to the square root of the dielectric constant, but the two values you mention are for two entirely different frequency bands. For frequencies below 100 MHz the dielectric constant is 81. The index of refraction of 1.33 you mention is for the visible region (~0.6 THz) where the dielectric constant is 1.76
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