Read about griffiths | 16 Discussions | Page 1

  1. SamRoss

    I Seeking better explanation of some quantum stats formulae

    In "Introduction to Quantum Mechanics", Griffiths derives the following formulae for counting the number of configurations for N particles. Distinguishable particles... $$ N!\prod_{n=1}^\infty \frac {d^{N_n}_n} {N_n !} $$ Fermions... $$ \prod_{n=1}^\infty \frac {d_n!} {N_n!(d_n-N_n)!}$$...
  2. kmm

    I Confused about some notation used by Griffiths

    I worked out the expectation values of the components of a 1/2 spin particle. However, I'm confused about Griffiths notation for the x and y components. For the x component I got, ## \left< S_x \right> = \frac \hbar 2 (b^*a+a^*b)## which is correct, but Griffiths equates this to ##...
  3. kmm

    Particle Is Griffiths Introduction to Elementary Particles up to date?

    I have a copy of Griffiths Introduction to Elementary Particles (1st Edition) and was thinking of beginning to work through it. I was curious if anyone knows if this text is sufficiently up to date or if there have been any major developments in particle physics that would make it worth getting...
  4. P

    Courses Review Griffiths E/M before Jackson?

    Hello, I will be starting my junior year this August, I shall be having the dreaded advanced electromagnetism course that follows Jackson's book the coming semester. Unfortunately, I didn't work very hard during my freshman year e/m course (which uses Griffiths' book) and have a few gaps in my...
  5. WeiShan Ng

    [QM] Two-Particle Systems: overlapping/non-overlapping wavefunctions

    Homework Statement Hi, I was reading Griffiths and stumble upon some questions. This is from 5.1.2 Exchange Forces. The section is trying to work out the square of the separation distance between two particles, $$\langle (x_1 - x_2)^2 \rangle = \langle x_1^2 \rangle + \langle x_2^2 \rangle -...
  6. sams

    I Finding Real and Imaginary Parts of the complex wave number

    In Griffiths fourth edition, page 413, section 9.4.1. Electromagnetic Waves in Conductors, the complex wave number is given according to equation (9.124). Calculating the real and imaginary parts of the complex wave number as in equation (9.125) lead to equations (9.126). I have done the...
  7. W

    I Questions Regarding Free Particles - Griffith's QM (I)

    Homework Statement [/B] 1) I don't quite understand what 2.94 means on its own. It was derived from 2.93, yet it doesn't show a superposition of any sort. The author then takes 2.94, and attempts to normalise it by stating ##\int \Psi_k^* \Psi_k dx = \mid A^2 \mid\int dx = \infty ## What...
  8. W

    Quantum Mechanics: Expectation values (Griffiths)

    Homework Statement A few questions: Q1) How does 1.29 flow to 1.30 and 1.31? How was the integral-by-parts done? Q2) The author states that <v> = d<x>/dt represents the expectation value of velocity. What does this actually mean? I tried to rationalise that d<x>/dt represented the velocity...
  9. G

    Proving that torque is m X B

    Homework Statement Starting from the Lorentz force law, in the form of Fmag = ∫ I (d× B), show that the torque on any steady current distribution (not just a square loop) in a uniform field B is m × B. Homework Equations I looked at the solution I found in this thread here, but I don't...
  10. S

    Classical Purcell to Jackson?

    I heard that Griffith's Electrodynamics is at a similar level of Purcell's book on electricity; is it fine if someone goes into a graduate level electrodynamics book right after Purcell?
  11. NicolasPan

    Find the electric field of a uniformly polarized sphere

    Homework Statement We want to calculate the field of a uniformly polarized sphere of radius=R Homework Equations V(\vec{r}) = \frac{1}{4 \pi\epsilon_{0}} \oint_{S} \frac{\sigma_{b}}{r} da' + \int_{V} \frac{\rho_{b}}{r} d\tau' The Attempt at a Solution i)I know that \sigma_{b} = P...
  12. F

    How to find the charge density given by a Tricky Potential?

    Homework Statement I am trying to solve Problem 2.45 in Electrodynamics by Griffiths, however, my answers were different from those in the book, I am suspect I got a missing step but I could not find it, so here is the Given Problem Find the charge density \rho given by a potential...
  13. entropy1

    Self-studying QM?

    Whole my life I have been interested in Quantum Physics. I have a bachelor degree in IT. I did not finish my studies. I have always been quite sloppy in studying in school. As a result, my mathematics skills are terrible. I often get pointed out on this forum that I better start with the...
  14. almarpa

    Quantum Griffiths' revolutions in 20th century physics

    hello all Prior to my studies in QM I would need a brief intro to quantum physics. I know there are lot of books on modern physics that cover these topics, but really like Griffiths' style, and my QM textbook is precisely his QM book. So, my question is if "revolutions in 20th century physics"...
  15. D

    Problem 2.4 Griffiths E&M 3rd ed -- E-field above a square loop

    Homework Statement The problem states, "Find the electric field a distance z above the center of a square loop (sides of length a) carrying a uniform line charge λ. " The hint says to use the result of example 2.1. Example 2.1 is a similar problem, but instead of a square loop you are asked...
  16. S

    Shankar, Feynman, Griffiths and Resnick?

    I know there are a lot of similar questions here but just hear me out. I am going to start self-studying quantum mechanics in a few days. I think I am going to use the MIT quantum mechanics 1 lectures as a starting point. But books will be essential as I spend most of my time in school. I have...