Recent content by AwesomeTrains

  1. AwesomeTrains

    I Help understanding the formula for the total phase shift of a waveplate stack

    I have problems deriving a formula in a paper I'm reading for a project. The paper is about putting a number of waveplates in series rotated relatively to each other to form a tuneable broadband waveplate. For the i-th waveplate the jones matrix is given by: $$ J_{i}(\delta_i, \Theta_i)=...
  2. AwesomeTrains

    Effective refractive index of a stratified medium

    I ended up solving the equation numerically which gave me a pretty good fit to the measured values. The numerical solution works until approximately 500 GHz which is where the conditions from post #5 aren't holding anymore, so that is probably the explanation and then expanding to third order...
  3. AwesomeTrains

    Effective refractive index of a stratified medium

    Here's my derivation: (I missed the minus sign in the original post) ## \frac{\alpha_2}{\mu_2} \tan\left(\frac{b\alpha_2}{2}\right)=-\frac{\alpha_1}{\mu_1} \tan\left(\frac{a\alpha_1}{2}\right) ## First I expand the tangents on both sides: ##...
  4. AwesomeTrains

    Effective refractive index of a stratified medium

    Hello PF, I'm reading a paper for a project. In the paper they derive an equation for the effective refractive index ##n=\sqrt{\epsilon^{e} \mu^{e}}## of two stacked layers ##(n_1^2 = \epsilon_1 \mu_1, a)## and ##(n_2^2 = \epsilon_2 \mu_2, b)## where ##a,b## are the lengths and in my case...
  5. AwesomeTrains

    Trying to understand a derivation in a paper

    Thanks for the help! I should be able to get it now, I was trying hard to solve for the k in the alphas :oldeyes:
  6. AwesomeTrains

    Trying to understand a derivation in a paper

    Thanks for the response. Sorry for the bad quality of the picture, the font is not so clear. It's a chi and not a k, k is in the alphas. I should have written all the definitions in the first post to clarify, my bad :oldeyes: \alpha_1 = k \sqrt{n_1^2-n^2}, \alpha_2 = k \sqrt{n_2^2-n^2} and...
  7. AwesomeTrains

    Trying to understand a derivation in a paper

    Hello PF, first of all I don't know where to put this post as it's not exactly a homework question but a clarification question for a project. I'm going through the derivation of the effective permeability of two stacked medias, given the polarization of an incoming EM wave but I'm stuck at the...
  8. AwesomeTrains

    Determing equation of state from thermodynamic coefficients

    I cannot seem to get the differential fiddled into parts like: ##f(V)dV = g(T)dT + h(p)dp## the best I could do is something like: $$dV+V\left(\frac{dp}{p}-\frac{dT}{T}\right) = \frac{-adp}{T^2}+\frac{3adT}{T^3}$$ or $$\frac{1}{V}\left(dV+\frac{adp}{T^2}-\frac{3adT}{T^3}\right)=...
  9. AwesomeTrains

    Determing equation of state from thermodynamic coefficients

    My calculation for ##F## didn't really seem to go anywhere, added it to the question just in case it could have been useful. ##dV(T,p) = \frac{\partial V}{\partial T}dT + \frac{\partial V}{\partial p}dp \implies \int \frac{dv}{v} = -\int \kappa_T dp + \int \alpha_p dT \implies## $$ln~V =...
  10. AwesomeTrains

    Determing equation of state from thermodynamic coefficients

    I don't have the source but I attached a screenshot of the problem sheet as it was handed out.
  11. AwesomeTrains

    Determing equation of state from thermodynamic coefficients

    Homework Statement The isobaric expansion coefficient and the isothermal compressibility are given by: $$\alpha_p = (1/V)(\partial V/\partial T)_p \quad \kappa_T = -(1/V)(\partial V / \partial p)_T$$ Suppose they have experimentally been determined to be: $$ \alpha_p = \frac{1}{T} +...
  12. AwesomeTrains

    Density matrix for a mixed neutron beam

    Thanks a lot for the help and patience! The last part of the question I think I can do on my own now. Have a nice weekend :)
  13. AwesomeTrains

    Density matrix for a mixed neutron beam

    ## \rho = \sum_n c_n | n \rangle \langle n |= c_1|+\rangle_x \langle + |_x+c_2|+\rangle_y \langle + |_y\\=\frac{c_1}{\sqrt{2}} \begin{pmatrix} 1 \\ 1 \\ \end{pmatrix} \frac{1}{\sqrt{2}} \begin{pmatrix} 1^{*} & 1^{*}\\ \end{pmatrix}+ \frac{c_2}{\sqrt{2}} \begin{pmatrix} 1 \\...
  14. AwesomeTrains

    Density matrix for a mixed neutron beam

    Sorry about the misconception I got a bit confused myself since I've seen quite a few different notations in my lecture and on the internet. ##|+\rangle_y=\frac{1}{\sqrt{2}} \begin{pmatrix} 1 \\ i \\ \end{pmatrix}## and ##|+\rangle_x=\frac{1}{\sqrt{2}} \begin{pmatrix} 1 \\ -1...
  15. AwesomeTrains

    Density matrix for a mixed neutron beam

    It's because it's the eigenstate of ##\hat{S}_z = \frac{1}{2} \sigma_z =\frac{1}{2} \begin{pmatrix} 1 & 0 \\ 0 & -1 \\ \end{pmatrix} ## if ## |+\rangle ## is represented as ## \begin{pmatrix} 1 \\ 0 \\ \end{pmatrix} ##
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