Talk:Refractive index

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Another possible error in language when explaining the basic concept

The article says, "the refractive index of water is 1.333, meaning that light travels 1.333 times slower in water than in a vacuum. This language may be a bit ambiguous, as there are two interpretations: the speed of light in water may be (c÷1.333) or (c - 1.333×c). Maybe, it could say, "the speed of light in a vacuum is 1.333 times that in water"? Ethan Lestat (talk) 15:14, 30 November 2020 (UTC)[reply]

"how fast light travels" vs "how slowly light travels"

In the introduction, I noticed the refractive index is explained to be "how fast light travels" through a material. And yet, as the refractive index of a material increases, the speed of light in the corresponding material decreases.

Is it then clearer to explain that refractive index is "how slowly light travels" through a material? Put another way, the more refractive index a material has, the slower light passes through it - so can it be interpreted that refractive index measures slowness?

2601:80:C97F:EFD0:C901:84BE:3D6A:D71D (talk) 06:54, 23 December 2021 (UTC)[reply]

Yes I would say so. But it doesn't really matter if we say "it measures slowness" or "it measures fastness", because if we look at it this way, "how fast light travels" is nothing but the quality or state of light being fast or slow. It would consider both the slowness and fastness of the speed of light. It has probably become a convention of saying that Refractive index is "how fast light travels". Arnav Raj Singh91 (talk) 02:57, 7 June 2023 (UTC)[reply]

Inconsistency in complex refractive index

We have defined $$\overbar{n} = n - i\kappa$$ but then in the formulae below we substitute $$\overbar{n} = n + i\kappa$$. Is it true that it only makes sense to define $$\overbar{n} = n - i\kappa$$ when we adopt the other convention, that $$E = exp(i(\omega t - k x))$$?

Optical extinction coefficient is not absorption coefficient?

In the complex refractive index section, it states: "the imaginary part κ is called the optical extinction coefficient or absorption coefficient." But I don't think those can be the same because the extinction coefficient is unitless but the absorption coefficient has units of 1/length. Quicknick5k (talk) 00:08, 4 September 2024 (UTC)[reply]

@Quicknick5k I applied a fix, please review. Sadly Attenuation coefficient is complete bogus.

I don't have Hecht with me, so I can't verify what it says on the subject. Johnjbarton (talk) 01:05, 4 September 2024 (UTC)[reply]