Recent content by jasonRF

  1. J

    Article about 17 year-old math talent

    I thought this was an interesting article that some of you may enjoy. It begins with: After finding the homeschooling life confining, the teen petitioned her way into a graduate class at Berkeley, where she ended up disproving a 40-year-old conjecture...
  2. J

    Engineering Physics Major Considering Masters in EE -- Need help!

    I have been an EE in industry for 25+ years, and have worked with very few EEs who were PEs. It just is not required for most jobs. At least when I was in EE grad school there were a number of students with physics undergraduate degrees. How a given department handles gaps in the student's...
  3. J

    I Justification of Superposition of Waves with Different Speeds

    I have been away for awhile so missed this thread. The OP is missing the fact that linear dispersive waves have 'wave equations' that look different than the one they are used to. For example, the electric field of a simple high-frequency transverse electromagnetic wave in a plasma (the...
  4. J

    What are some less famous equations that you must know as an undergraduate physicist?

    Boltzmann transport equation Fluctuation-dissipation theorem
  5. J

    Plasma Books on Plasma Instabilities?

    Most plasma physics texts - either general or those emphasizing plasma waves - include quite a bit of discussion on plasma instabilities. Which books are have you looked at or studied from? Once you are familiar with the basic theory and types of calculations needed to investigate...
  6. J

    I Is there an alternative to Taylor series but with differences?

    There is something that is sometimes described as 'difference calculus'. The equivalent to a Taylor series would be the interpolating polynomial. See, for example, https://encyclopediaofmath.org/wiki/Finite-difference_calculus Hamming's Numerical Methods for Scientists and Engineers has a...
  7. J

    Astrophysics Best textbook on plasma physics

    I agree that Chen is a good start. Another reasonable option is Gurnett and Bhattacharjee. https://www.amazon.com/Introduction-Plasma-Physics-Astrophysical-Applications/dp/1107027373/?tag=pfamazon01-20 Used copies of prior editions are fine for either text. I would also recommend...
  8. J

    Does constant DC current in curved wire produce EM wave?

    I agree with others that say in the steady state, the DC current loop will not radiate. When I am unsure about my physical understanding or intuition, I fall back on the math. The vector potential ##\mathbf{A}(\mathbf{r},t)##is related to the current density ##\mathbf{J}(\mathbf{r},t)## by...
  9. J

    Astronomy Good Book Recommendations on Solar Physics

    Introduction to Space Physics by Kivelson and Russel is a nice book. Assumes you know upper division undergrad electrodynamics. https://www.cambridge.org/highereducation/books/introduction-to-space-physics/BA017948E00BF032AA06D8D2BFD8062F#overview
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    Applied A question about mathematics textbooks for physicists

    Is more advanced than Boas, but less advanced (and much easier reading) than books like Courant and Hilbert, Morse and Feschbach. According to the authors, part of the book can easily be used for undergrads. The entire book is a reasonable read if you have taken a solid course in complex...
  11. J

    I Why don't we talk about the E & H fields instead of E & B fields?

    in what way are E and H parallel to each other? At least in simple media they are perpendicular. That does not describe every book. For example, Field and Wave Electromagnetics by Cheng. I do think engineering-oriented texts are probably more likely to use E and H then physics texts. As an...
  12. J

    Laplace transform vs phasor analysis in circuit analysis

    The two methods are related, but it depends on where the Laplace transform converges. I posted about this in a different thread awhile ago. https://www.physicsforums.com/threads/physical-significance-of-the-laplace-transform.971324/post-6174503 jason
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    I Can the Last Maxwell's Equation Explain Polarization of a Wire's Insulator?

    Wrong. Consider ##\mathbf{V}_1 = y\mathbf{\hat{x}} + x\mathbf{\hat{y}} + y\mathbf{\hat{z}}##. What reading have you been doing? Because I haven't seen the polarization field in any of your equations. If you want to use that form of the equation, the polarization field must be in your current...
  14. J

    B Understanding the Relationship Between i*cos and sin in Circuit Analysis

    Since you claim to understand phasors, why don’t you use them the same way as all other EEs I have ever worked with and gone to school with? Were you taught this method? Of course, if ##\omega t## is real then ##\cos(\omega t)## is real and ##i \, \sin(\omega t)## is imaginary, so they are...
  15. J

    B Proof of the relation between antenna aperture and gain

    There are some fundamental limits on the bandwidth of small antennas that were proved many decades ago. The wikipedia page gives the references https://en.m.wikipedia.org/wiki/Chu–Harrington_limit Basically, small antennas have a high Q so are narrowband. Jason
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