In optics and lens design, the Abbe number, also known as the V-number or constringence of a transparent material, is an approximate measure of the material's dispersion (change of refractive index versus wavelength), with high values of V indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist who defined it. The term V-number should not be confused with the normalized frequency in fibers. The Abbe number, Vd, of a material is defined as where nC, nd and nF are the refractive indices of the material at the wavelengths of the Fraunhofer C, d, and F spectral lines (656.3 nm, 587.56 nm, and 486.1 nm respectively). This formulation only applies to the visible spectrum. Outside this range requires the use of different spectral lines. For non-visible spectral lines the term V-number is more commonly used. The more general formulation defined as, where nshort, ncenter and nlong are the refractive indices of the material at three different wavelengths. The shortest wavelength index is nshort and the longest is nlong. Abbe numbers are used to classify glass and other optical materials in terms of their chromaticity. For example, the higher dispersion flint glasses have V < 55 whereas the lower dispersion crown glasses have larger Abbe numbers. Values of V range from below 25 for very dense flint glasses, around 34 for polycarbonate plastics, up to 65 for common crown glasses, and 75 to 85 for some fluorite and phosphate crown glasses. Abbe numbers are used in the design of achromatic lenses, as their reciprocal is proportional to dispersion (slope of refractive index versus wavelength) in the wavelength region where the human eye is most sensitive (see graph). For different wavelength regions, or for higher precision in characterizing a system's chromaticity (such as in the design of apochromats), the full dispersion relation (refractive index as a function of wavelength) is used. (Wikipedia).

Conversion Arcs and 2,916,485,648,612,232,232,816 (MegaFavNumbers)

I'm sorry. The MegaFavNumbers playlist: https://www.youtube.com/playlist?list=PLar4u0v66vIodqt3KSZPsYyuULD5meoAo

From playlist MegaFavNumbers

Irrational Numbers - What are they?

Learn what an irrational number is in this free math video tutorial by Mario's Math Tutoring. 0:07 What is an Irrational Number 0:11 What is an Integer 0:35 Example of a Rational Number 7 1:02 Example of How a Repeating Decimal is Rational 1:26 Example 1 is Square Root of 7 Rational? 1:40

From playlist Algebra 1

#MegaFavNumbers - 7,588,043,387,109,376 by Egi

87,109,376^2=7,588,043,387,109,376. The last 8 digits is the square root😀, it's called an automorphic number which n^2 ends with n

From playlist MegaFavNumbers

Imaginary numbers are any numbers that include the imaginary number i. A mix of imaginary and real numbers gives you what’s called a complex number. The primary reason we use imaginary numbers is to give us a way to find the root (radical) of a negative number. There’s no way to use real

From playlist Popular Questions

Computation Ep22, Stack Machines (Mar 23, 2022)

This is a recording of a live class for Math 3342, Theory of Computation, an undergraduate course for math and computer science majors at Fairfield University, Spring 2022. The course is about finite automata, Turing machines, and related topics. Homework and handouts at the class websi

From playlist Math 3342 (Theory of Computation) Spring 2022

#MegaFavNumbers: 10,904,493,600 & Fibonacci Numbers

This is my #MegaFavNumber. Link to all the #MegaFavNumbers Videos: https://www.youtube.com/watch?v=R2eQVqdUQLI&list=PLar4u0v66vIodqt3KSZPsYyuULD5meoAo Channel Links: Website: https://sites.google.com/view/pentamath Channel: https://www.youtube.com/channel/UCervsuIC9pv4eQq98hAgOZA Subscri

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Stanford Webinar - 3 Winning Strategies to Beat Low Cost Competitors

In this 2nd webinar, we will switch from threat to response options. We will introduce a simple conceptual framework to help executives and managers think about the possible ways their companies can respond to the low cost challenge. Should they confront the LCCs in their market segments a

From playlist Stanford Webinars

The Dark Ages...How Dark Were They, Really?: Crash Course World History #14

John Green teaches you about the so-called Dark Ages, which it turns out weren't as uniformly dark as you may have been led to believe. While Europe was indeed having some issues, many other parts of the world were thriving and relatively enlightened. John covers European Feudalism, the cu

From playlist World History

AVOGADRO'S NUMBER - a quick definition

A quick definition of Avogadro's Number. Chem Fairy: Louise McCartney Director: Michael Harrison Written and Produced by Kimberly Hatch Harrison ♦♦♦♦♦♦♦♦♦♦ Ways to support our channel: ► Join our Patreon : https://www.patreon.com/socratica ► Make a one-time PayPal donation: https://w

From playlist Chemistry glossary

Can You Navigate If You Don't Know Where You Are?

Suppose you are completely lost at night, you do have a map but you can't read the street signs. Can you find your way? The mathematics of synhronization. Links and resources: Penn & Teller's clock trick on Fool Us: https://www.youtube.com/watch?v=t-uXRepVPOg&t=2017s&ab_channel=ikaamowa

From playlist Summer of Math Exposition Youtube Videos

Slowly into Secret Scotland | National Geographic

Join National Geographic travel photographer Michael George as he takes a slow journey by bike through the Scottish Borders. Follow him as he visits historic houses, ancient abbeys, hidden lochs and meets friendly locals each with a story to share. His journey in the south of Scotland take

From playlist Newest Clips | National Geographic

1,010,010,101,000,011 - #MegaFavNumbers

This is my submission to the #megafavnumbers project. My number is 1010010101000011, which is prime in bases 2, 3, 4, 5, 6 and 10. I've open-sourced my code: https://bitbucket.org/Bip901/multibase-primes Clarification: by "ignoring 1" I mean ignoring base 1, since this number cannot be fo

From playlist MegaFavNumbers

Coding Challenge 171: Wave Function Collapse

Straight out of quantum mechanics, Wave Function Collapse is an algorithm for procedural generation of images. https://thecodingtrain.com/challenges/171-wave-function-collapse In this video (recorded over 3 live streams) I attempt the tiled model and explore a variety of solutions to the

From playlist Coding Challenges

How The Pandemic Has Affected Corporate Training | Corporate Training Post Pandemic | Simplilearn

🔥Explore our FREE Courses with Completion Certificates: https://www.simplilearn.com/skillup-free-online-courses?utm_campaign=WebinarSep9&utm_medium=DescriptionFirstFold&utm_source=youtube The COVID-19 pandemic has upended traditional corporate learning and development approaches. Not only

From playlist Simplilearn Live

What are Irrational Numbers? | Number System | Don't Memorise

Watch this video to know more about Rational numbers, Irrational Numbers, Real Numbers and Number System. To learn more about Irrational Numbers, enroll in our full course now: https://infinitylearn.com/microcourses?utm_source=youtube&utm_medium=Soical&utm_campaign=DM&utm_content=CtRtXoT_

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History of the Light Bulb 1705 to 1809

The light bulb is way older than you think! Take a journey through time from Newton's assistant to glowing books to jumping dead frogs to the arc lamp all with tons of demonstrations. Links: My Patreon Page: https://www.patreon.com/user?u=15291200 The man with the glowing ball and the

From playlist History of Lighting (War of the Currents)

Stack machines: Theory of Computation (Mar 16 2021)

This is a recording of a live class for Math 3342, Theory of Computation, an undergraduate course for math & computer science majors at Fairfield University, Spring 2021. Class website: http://cstaecker.fairfield.edu/~cstaecker/courses/2021s3342/

From playlist Math 3342 (Theory of Computation) Spring 2021

MegaFavNumbers - A number with 19729 digits

This video is about my MegaFavNumber. It has 19729 digits, and it is a power of two. [This link is now broken, and I can't find it anywhere else. :( ] See all the digits here: https://sites.google.com/site/largenumbers/home/appendix/a/numbers/265536 The OEIS sequence I mentioned: https:/

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IMT4307 - Serious Games (Security Awareness) - Part 1

Serious Games Topic: Security Awareness

From playlist Archive - Serious Games

My #MegaFavNumber - The Bremner-Macleod Numbers

Much better video here: https://youtu.be/Ct3lCfgJV_A

From playlist MegaFavNumbers