# Search results

1. ### Converging Lasers of Different Wavelengths

I hope this is the right place to ask this. It is an experiment question. I have a 785 nm laser and a 1550 nm laser and I need to converge them down to a point. Now I could just manually align the lasers on the same XY-plane and have them hit that spot, but for reasons I don't want to...
2. ### How to go about solving this first-order nonlinear differential equation?

I saw this post at stackexchange: I ran across this post when trying to solve a homework problem. But I have no idea how he got that solution for that. When I use the Euler-Lagrange, I get this diff eq below. Here is the simplest form I have managed to get it in...
3. ### Tips on writing the Lagrangian

Hey guys. I'm trying to gather some tips that people have acquired that helps them write the Lagrangian for a system. Obviously, the classic examples are drilled into our heads over and over, but just when you think you can tackle any problem the professor throws at you, there is that tricky one...
4. ### Derivation of Potential Energy for two masses attached to three springs

First of all, my question isn't completely unrelated to a homework question. I know how to answer that question using definitions in the book and mechanically get to the end. But I wanted to start from basic principles and arrive at the same answer. This lead to a contradiction which sent me on...
5. ### Quick help needed on a Matrix Multiplication

I have a small problem where I remember I learned it in the past. But now I can't seem to recall how to do it. I searched on google, but I think even though it is probably really easy, I may not have worded it right to get the references I want. So I decided to ask here. Here is the problem...
6. ### A Geometry problem that is giving me trouble

So here is a picture I quickly made in photoshop that has the problem: [PLAIN]http://img21.imageshack.us/img21/9406/trigproblem.png [Broken] The rectangle's dimensions are known. (w & h) So it follows that the angle, "@", and the diagonal, "d", is also known. The width between the two...
7. ### Question about length contraction (geometric way)

I'm doing some independent study with a professor at my university. He has taken one GR class and he said that it was not a good experience. So we are in a sense learning together as we pursue this. We are using the book "A First Course in General Relativity" by Schultz. We are doing problem...
8. ### Hall Effect Probe/Sample Mount (Design)

Me and a friend are working on a research project that involves four-point electrical measurements. (Van der pauw) To do a hall effect measurement, the sample and probes have to have a strong magnetic field pass through. So we want some design ideas on constructing the mount that will have to be...
9. ### X-ray Fluorescence angle question.

First of all, I'm not the one doing this experiment. I've just finished my first year in college and I'm sort of just helping all the upper-level with their research and whatnot. So my knowledge is very limited. With that being said, one of those student is doing X-ray Fluorescence. He was...