Read about e&m | 20 Discussions | Page 1

  1. S

    Find the angular acceleration of two reflectors attached to a rod

    Okay so I actually have the answer because my teacher basically just gave it to me, but I would really like to know why I was even wrong in the first place. Here's my steps: 1. Knowing the momentum transfer per unit area is described by: 1/A dp/dt = S/c. I can begin by relating some known...
  2. F

    What happens to σ (conductivity) when the permitivity is negative?

    We are using the textbook by Jin, "Theory and Comutation of Electromagnetic Fields". In the section on metamaterialshe derives the dispersion relationship. He shows that when ε'= -ε & μ' = μ then the dispersion equation γ =\sqrt{jωμ( jωε +σ )} = α + jβ goes to γ = α = ω \sqrt{μ'ε'}...
  3. S

    I Textbook says V=E/w but units don't match

    In my textbook, it is talking about the Hall Effect on a flat conductor with width w carrying a current i in a uniform magnetic field perpendicular to the plane of the strip. It says that this will create a potential difference of V=E/w where E is the induces electric field from the electrons...
  4. B

    Polarizibility, Electric Field & Force

    Homework Statement A neutral atom with known polarizability α is located at the origin. A point charge Q is situated on the y-axis a large distance d from the atom. (The atom therefore becomes polarized due to the electric field of the point charge.) (a) Find the electric field due to the atom...
  5. N

    E&M: Prove the Divergence Theorem

    Homework Statement Griffiths Introduction to Electrodynamics 4th Edition Example 1.10 Check the divergence theorem using the function: v = y^2 (i) + (2xy + z^2) (j) + (2yz) (k) and a unit cube at the origin. Homework Equations (closed)∫v⋅da = ∫∇⋅vdV The flux of vector v at the boundary of the...
  6. astrocytosis

    Induced current in a loop of wire when straight wire is cut

    Homework Statement A square loop, side a, resistance R, lies a distance s from an infinite straight wire that carries current I (pointing to the right). Now someone cuts the wire, so I drops to zero. In what direction does the induced current in the square loop flow, and what total charge...
  7. P

    Faraday's law of Induction

    Homework Statement I'm in a class where we have to essentially learn E&M ourselves and I'm challenged by Maxwells equations. I'm studying out of Purcell's E&M. The differential form of Faradays law for Maxwells equations is curl E = -∂B/∂t Im having trouble interpreting what to make of this...
  8. J

    Antenna Problem

    Hello all, I have a problem with a typical style of problem I seem to always struggle with. Just to clear this up, I am studying for my comprehensive exams later this summer. So I am going through past problems to bone up on the last two years of grad school. At which point I came across this...
  9. TBert

    I What is this effect

    A friend of mine showed me a diagram like this: I think they said it was describing the probability of finding a charged particle in a certain place when traveling over a voltage. They said that if the particle doesn't have enough energy to make it across then it gets stuck at the beginning...
  10. D

    Courses Can I catch up on physics 1 & 2 in 3 months?

    So I am currently an ME major at CC. I am probably going to transfer to a university to study physics next fall but there is one problem... I took physics 1 & 2 at a community college that is very heavily focused on their engineering program. Because of this, I only learned things in physics 1...
  11. Z

    Magnetic field in an offset hole in a conductor cylinder

    Homework Statement A long (infinite) wire (cylindrical conductor of radius R, whose axis coincides with the z axis carries a uniformly distributed current I in the +z direction. A cylindrical hole is drilled out of the conductor, parallel to the z axis, (see figure above for geometry). The...
  12. C

    Postion vs time graph without time or initial speed?

    Homework Statement Consider the system shown to the right. Particles 1 and 2 are fixed in place while particle three is placed at the location shown and released. Let’s look at the mechanics of q3, which has a mass of 3.00 X 10-5 kg. What will be the net force on q3? What will be...
  13. CentrifugalKing

    Circular Wave Fronts Emitted by Two Wave Sources

    Homework Statement https://session.masteringphysics.com/problemAsset/1383558/3/21.EX26.jpg Make a table with rows labeled P, Q, and R and columns labeled r1, r2, Δr, and C/D. Fill in the table for points P, Q, and R, giving the distances as multiples of λ and indicating, with a C or a D...
  14. R

    Magnitude and Direction of induced voltage

    Homework Statement Hey everyone I have a physics e&m question: [/B] http://blob:https%3A//www.physicsforums.com/aa779f37-be23-43d7-a888-d70263a3854b Homework Equations The Attempt at a Solution I took the derivative to find the magnitude of the induced voltage. (do I need to add a...
  15. DrPapper

    Vector Potential: Infinite Wire and Infinite Solenoid

    Homework Statement Homework Equations Provided in the questions I believe. Here's the triangle from question two. The Attempt at a Solution QUESTION SET 1 TOP OF PICTURE A.) I didn't know how to just "guess" what the constant should be so I actually worked it out. I found the constant...
  16. DrPapper

    Finding the Delta Function of a Thin Ring

    Homework Statement [/B] A very thin plastic ring (radius R) has a constant linear charge density, and total charge Q. The ring spins at angular velocity \omega about its center (which is the origin). What is the current I, in terms of given quantities? What is the volume current density J in...
  17. E

    Magnetic field and gradient along axis of antihelmholtz pair

    Homework Statement An anti-Helmholtz pair consists of two circular coaxial current loops each with radius R and spaced a distance R apart from each other. The loops carry current I in opposite directions. 1) Calculate the magnetic field and the magnetic field gradient along the axis at the...
  18. Elvis 123456789

    Classical Recommendation for rigorous intro books to mechanics and E&M

    Hey guys I'm a sophomore in college currently taking physics 2(intro E&M), Multivariable calculus, and Differential Equations. I was hoping some of you guys could recommend some good books for intro mechanics and E&M. I'm currently using University Physics by Young in my E&M class, and I used...
  19. N

    Jackson 1.12 & 1.13

    Homework Statement 1.12 - Prove Thomson's theorem : If a number of conducting surfaces are fixed in position and a given total charge is placed on each surface, then the electrostatic energy in the region bounded by the surfaces is a minimum when the charges are placed so that every surface...
  20. sheldonrocks97

    Is it Weird I Find Physics II easier than Physics I?

    Is it weird that I find physics II easier than physics I? I am currently in Physics II at university and flying through it with an A. However, I took Physics I at Community College and BARELY got a B. On my tests so far this semester I got a 87 on the first one and a 97 on the second one. In...
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