Recent content by KT KIM

More exact to say, I wanted to talked about, Photonic crystal fiber (including photonic bandgap fiber), maybe 'hollow optical fiber' was not a good word choice, excuse me.

in the air it is.

Now I am studying a bit of optical fibers. And of course generally optical fiber works because of total reflection property of the light, which happens when the light from higher medium hits the lower medium material. However I recently found out that there also is a thing 'Hollow optical...

I am now taking optics class at my school. Fermat principle can be applied on mirror of course. Then what about Concave mirror? According to the calculus of variation. the optimized path(actual path of the light) should be the shortest path. but in the concave mirror case, it goes through the...

Hi, I'm studying undergrad mechanics, Central force motion, Marion's book in specific, Here, the Potential Energy is defined weird way (in my opinion though) (μ is reduced mass) So potential Energy becomes Called "Effective Potential Energy" But, I can't agree with calling it potential just...

Really good one it is, Thank you.

I finally found out that actually I misread it!, Haha sorry, English is not my primary language. I did read like "sequence 'bounded' above converges." , have thought converges is just a noun. Anyway I really appreciate your help. Thank you

I am studying Classical Analysis with Marsden book. At very first chapter it covers sequence, field, etc... The book has theorems 1."Let F be an ordered field. We say that the monotone sequence property if every monotone increasing sequence bounded above converges." 2."An ordered field is said...

In basic level classical mechanics I've known so far The Lagrangian Equation is Like this But in the little deeper references, they covers Lagrangian Equation is Like this Qi is Generalized force, and Qi also contains frictions that's what reference says But I still can't grasp. What is the...

Thank you much for fine answer, helped me a lot. Guess need some time to grasp that notion well.

Studying Lagrangian mechanics starting from D'Alembert's principle. I just ran into this. Why virtual displacement doesn't contain time t for it's coordinates What does that mean 'take place at a fixed time'?

Thank you for clear explanation. Got the first one. Yes Σij rij x Fji = 0 so eventually it makes L dot = tau (torque) But, what I want know is the mathematical manuever that makes ri X Fji = 1/2(rij X Fji)

This is from text [Introduction to Lagrangian and Hamiltonian Mechanics] on NTNU opencourse. Annnnd... I don't use english as my primary language, so sorry for poor sentences. I can't get two things in here. First, at (1.12) I can't understand how L dot derivated like that. Since I know...

Geez.. I never knew this book is that wrong. However it is really hard to get cat one in my country(too expensive or out of stocks in here s.korea), maybe I should look for other options.

I want to study quantum mechanics for undergrad level, and found out really lots of people recommends "Introduction to Quantum Mechanics by David J.Griffiths" which is Alright, so I visited my school book store for this cat-pictured book. and found this puzzle-pictured book. Same name same...