Explain the value of refractive index of water?

AI Thread Summary
The refractive index of water is commonly cited as 1.33, which differs from the calculated value of 9 due to the use of an incorrect relative permittivity for visible wavelengths. The relative permittivity of water varies with frequency, impacting the refractive index. The discussion emphasizes the importance of using appropriate values for specific wavelengths when calculating refractive indices. Understanding these nuances is crucial for accurate optical measurements. The conversation concludes with acknowledgment of the clarification provided.
Yen Pham
Messages
2
Reaction score
0
I have studied about the formula of refractive index which is:
dbff99e30f01687f56047d647d3186d6.png
. That means in the case of water which have μ =1 (approximate) and ε = 81, then n should be 9. But why we often use the value n = 1.33 for water ?
Who can explain for me? I don't think the above formula is wrong, of course!
 
Science news on Phys.org
You have taken a value for the relative permittivity which is not valid for visible wavelengths. The permittivity (and hence refractive index) changes with the frequency.
 
  • Like
Likes Yen Pham
Orodruin said:
You have taken a value for the relative permittivity which is not valid for visible wavelengths. The permittivity (and hence refractive index) changes with the frequency.
yeah, I got it! Thank you so much^^
 
Thread 'A quartet of epi-illumination methods'

Thread 'A quartet of epi-illumination methods'

Well, it took almost 20 years (!!!), but I finally obtained a set of epi-phase microscope objectives (Zeiss). The principles of epi-phase contrast is nearly identical to transillumination phase contrast, but the phase ring is a 1/8 wave retarder rather than a 1/4 wave retarder (because with epi-illumination, the light passes through the ring twice). This method was popular only for a very short period of time before epi-DIC (differential interference contrast) became widely available. So...
View full post »

Thread 'Effective absorption coefficient of gold nanoparticles'

I am currently undertaking a research internship where I am modelling the heating of silicon wafers with a 515 nm femtosecond laser. In order to increase the absorption of the laser into the oxide layer on top of the wafer it was suggested we use gold nanoparticles. I was tasked with modelling the optical properties of a 5nm gold nanoparticle, in particular the absorption cross section, using COMSOL Multiphysics. My model seems to be getting correct values for the absorption coefficient and...
View full post »

Thread 'The focal length of the eye and image inversion'

After my surgery this year, gas remained in my eye for a while. The light air bubbles appeared to sink to the bottom, and I realized that the brain was processing the information to invert the up/down/left/right image transferred to the retina. I have a question about optics and ophthalmology. Does the inversion of the image transferred to the retina depend on the position of the intraocular focal point of the lens of the eye? For example, in people with farsightedness, the focal point is...
View full post »

Similar threads

Is the index of refraction constant for a given medium?
Replies
7
Views
4K
Can refractive index of a material be less than unity?
Replies
20
Views
12K
Do the Relative Permittivity and Refractive Index of Water Match Up?
Replies
1
Views
4K
Refractive index using a traveling microscope
Replies
3
Views
3K
Why is the refractive index for red lower than for blue?
Replies
7
Views
3K
Why Does Snell's Law Give Incorrect Results When Using Certain Formulas?
Replies
3
Views
1K
Refractive Index change with Wavelength & Carrier Concentration
Replies
14
Views
5K
Is it possible for the index of refraction to be zero in Snell's law?
Replies
2
Views
3K
Reflection and transmission of waves in a medium of nonuniform density
Replies
10
Views
2K
I Why is Cherenkov radiation blue? And what about refractive index?
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top