What is Moving charge: Definition and 93 Discussions

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1. B Exploring the Electric Field of a Moving Charge

How does an electric field of a moving charge, for example a moving electron, inside a wire looks like? Does it looks like this with distorted circular radial lines?
2. Electric and magnetic fields of a moving charge

Part a) My solution: Big R basically becomes r, and the electric and magnetic field lines are doubled because of superposition principle. Am I right?
3. I Electric field of a moving charge that's abruptly stopped

Hello everyone, This is in reference to fig 5.19 (screen shot attached - please read the paragraph which says "Figure 5.19 shows the..."). I don't get why the field outside of the sphere of radius ct acts as though the particle would have continued its motion. Author's words : "The field...
4. The potential electric and vector potential of a moving charge

I could try to apply the Liénard-WIechert equations immediatally, but i am not sure if i understand it appropriately, so i tried to find by myself, and would like to know if you agree with me. When the information arrives in ##P##, the particle will be at ##r##, such that this condition need to...
5. Electric force due to a moving charge

I am having some problems involving the force that a source moving with speed v along the x-axis would exert on a test charge at the x axis. Moving to the frame of the source charge, we got that the electric field it exerts is $$E' = kq/x'²$$ Now, moving back to the lab frame, and considering...
6. I Electric Field Directly Ahead of or Behind a Moving Charge

Since it is stated that ##E'_x = E_x##, I am going to set a special case where ##z' = z = 0##, ##E_x## in (5.10) reduces to, ##E_x = \frac{1}{4 \pi \epsilon_0}\frac{Q}{x^2}## However, ##E'_x## in (5.13) reduces to, ##E'_x = \frac{1}{4 \pi \epsilon_0}\frac{Q}{\gamma^2 x'^2}## There is an...
7. Electric Field of a moving charge

When a charge is at rest, it has an electric field only. When the charge starts moving , it is said to have accompanied a magnetic field. My question relates to its electric field while in motion. Does it still exist or not? I know in electron guns electrons are deflected while passing thru the...
8. B Magnetic field and moving charge special relativity

Hi. In a current carrying conductor because of special relativity amount of protons and electrons differ so we get an electric field or as we call it magnetic field. So if magnetic field is just an electric field how is it that the charge has to move so that magnetic field would exert a force on...
9. Magnetic Field of a Moving Charge and the Displacement Current

We all know a moving charge generates a magnetic field. A moving charge also generates a displacement current ∂E/∂t. Is the magnetic field generated entirely due to the presence of the displacement current, or is there an independent, separate effect which contributes to the magnetic field?
10. Maximum Horizontal Force of Relativistic Point Charge

Homework Statement A charge q1 is at rest at the origin, and a charge q2 moves with speed βc in the x-direction, along the line z = b. For what angle θ shown in the figure will the horizontal component of the force on q1 be maximum? What is θ in the β ≈ 1 and β ≈ 0 limits? (see image) Homework...
11. Magnetic field of a moving charge and Maxwell's equations

How can we calculate the magnetic field of moving charge by the Maxwell equation ##\nabla \times H=J+\frac {\partial D} {\partial t}##? I mean which term, ##J## or ##\frac {\partial D} {\partial t}##, should be taken into account in calculations? The first, second, or both? Can we deal with the...
12. Force on a stationary test charge from a moving charge

Given a test charge, let's say on the vertical y axis. Another charge vertically below it moves past at a significant speed compared to c. From the Lorentz transformations (in most E&M books) the electric field and thus the force on the test charge will be greater than would be the static...
13. Einstein Velocity Addition for a Moving Charge in a Wire

Homework Statement I am reading through Griffiths' Electrodynamics, and I have come to the scenario in the Relativity chapter where in an inertial reference frame ##S##, we have a wire, with positive charges (linear density ##\lambda##) moving to the right at speed ##v##, and negative charges...
14. Calculating Velocity Change in a Moving Charge-Magnet Interaction

Homework Statement A magnet is moving with constant velocity vector ##\vec V##. A charged particle fly through it. At first, the objects are place very far from each other, and the charged particle velocity vector is ##\vec V0##, after the charged particle cross over and fly away from the...
15. B Moving Charge in a Magnetic field Problem

Hi all. I am alluding to the Moving Charge in a Magnetic field problem by quoting an MIT lecture below. Scott Huges – Lecture http://web.mit.edu/sahughes/www/8.022/lec10.pdf Suppose we now examine this situation from the point of view of the charge (the “charge frame”). From the charge’s point...
16. I Force on Moving Charge: Lorentz Transformation & Point Charge

consider a frame S with a given electric and magnetic fields , and a single point charge. if we want to calculate the force on the charge in his rest frame we should use Lorentz transformation to find the electric field in his rest frame. if we believe that a given field is not related to his...
17. Attempt to find the magnetic field of a moving charge

First let me say THANK YOU to anyone who reads my work and tries to help, I know it can be a pain to decipher the work of others (although I've tried to make it as clear as possible). If any part is unclear I will try to explain it. I cannot for the life of me see any flaws in the argument...
18. Magnetic field of a moving charge and coulombs force

By relativity+coulombs force, I worked out that the (magnitude of the) magnetic field of a charge Q moving at speed V should be (ϒVV/c2)Q/(4πε0r2) or in terms of mu, ϒVμ0VQ/(4πr2) (where the distance r is measured normal to V). When I google the answer I only find the same thing but without the...
19. L

I Relativistic field of moving charge. Why is it symmetric?

Hi people! First of all, sorry for my poor english. I read in many places and I did the calculus and I agree that the field of a moving charge have this aspect: (Taked from Feynman´s Lectures on Physics chapter 26th.) But my problem is in that my intuition says me that it must be something...
20. Does a moving charge posess a generated magnetic field?

Hi all, This question has been bothering me for some time, so here it is. I know that moving a charged particle, like an electron, generates a magnetic field. I know that moving electric charges in a circle (a loop of wire) generates a magnetic field. The question is, will a charge moving in a...
21. Electrons move, causing magnetic force, find v?

Homework Statement Homework Equations f = q.v.B.sin tetha I = q/t = v/R The Attempt at a Solution (1) q =a.b.n.v.t is it right? (2) I = q/t = abnvt/t = abnv is it right? (3)F = q.v.B is it right? (4) ? (5) ? is it right?
22. P

Electric field of a moving charge?

I have a moving charge in a generic motion, and I pick a point p, how do I get the electric field caused by the charge on point p, at any time? Can I use the coulomb definition of electric field that relates it's strenght with the Distance? Or does that law works only when the charge is static...
23. I The Electric field of a moving charge according to Purcell

In Berkeley Physics Course (Volume II) on Electricity and Magnetism: https://www.scribd.com/doc/128728926/Electricity-and-Magnetism-Berkeley-Physics-Course-Purcell ...Purcell discusses the invariance of charge (Section 5.4), the electric field measured in different frames of reference (Section...
24. Magnetic field of moving charges

Hi! I wonder if there was any experimental measurement of magnetic field produced by mechanically moving charges. In principle the equation is well known. (1) But is there any experimental proof of this equation? I know it can be reformulated into this. (2) My question is "Is there any...
25. A Charged Particle moving in Uniform Magnetic Field

Homework Statement Problem given in the image attached. Uniform Magnetic Field : B Positive Charge : q Uniform Velocity : v Mass : m Charged particle enters the magnetic field making an angle θ with the plane perpendicular to the magnetic field. Width of the region of Magnetic field : d d <...
26. Infinitely charged wire and moving charge

Homework Statement There's a uniform infinite line charge with the charge density λ. A point particle with charge q moves with a velocity v parellel to infinite line. What is force exerted on point particle? What is magnetic field seen in ths moving frame(particle frame)? Homework Equations...
27. Magnetic field in frame of moving charge

A charge moving relative to some observer produces magnetic field in space around it. Now I want to ask that how does the magnetic field of the charge at any fixed point varies as the charge passes by. Or is the B field only dependent on current and not a single moving charge? If I introduce...
28. Explaining Magnetic Force on Iron Without Moving Charge

Hi, I am a high school physics student and the only ways we learned to calculate the magnitude of a magnetic force involved a moving charge or current in a wire. As a result I have wondered how a bar magnetic magnet may exert a force on a piece of iron, since there is no clear movement of charge...
29. Potential energy of moving charge in field

Homework Statement 1. Homework Statement [/B] Prove the potential energy of interaction between an electric charge ##q## moving with velocity ##\vec{v}## and an electromagnetic field with potentials ##V## and ##\vec{A}## is given by ##U = qV-q \vec{v} \cdot \vec{A}## Homework Equations...
30. E-field of a moving charge at constant velocity

I came upon this page that provides the answer: http://farside.ph.utexas.edu/teaching/em/lectures/node125.html But I can't figure out what gamma(u) is. Could anyone help?
31. What statement about magnetic fields interacting with a moving charge is correct?

What statement about magnetic fields interacting with a moving charge is correct? A) Magnetic fields can’t change the direction of motion of a moving charge. B) Magnetic fields can do work on a moving charge. C) Magnetic fields can accelerate a moving charge. D) The force on a moving charge in a...
32. Work done moving charge near a line of charge

Homework Statement How much work (in J) is required to bring a charge of 2 microC from the point {2*6.8,-7,2*1.1}cm via the point {10,20,1}cm to the point {-3*6.8,3.4,-3*1.1}cm, in a medium with relative permittivity of 3.7, near a line charge along x=6.8 cm, z=1.1 cm, with charge density +329...
33. Work done by moving charge from one sphere to another?

Homework Statement Consider two metal spheres, sphere 1 having radius R1 = 20 cm, and sphere 2 having a radius R2 = 10 cm. The two are rather close to one another, separated by a center-to-center distance of only 80 cm. Suppose now that they are connected to each other by a thin wire that is...
34. Magnetic field of a moving charge

Homework Statement A negative charge q = −3.20×10-6C is located at the origin and has velocity υ⃗ =(7.50×104m/s)ι^+((−4.90)×104m/s)j^. At this instant what is the magnetic field produced by this charge at the point x = 0.230 m , y = -0.300 m , z= 0? Give the x, y and x components Homework...
35. Moving charge magnetism explanation

I'm from a country in Africa where I didn't have the privilege of learning the Standard Model, so I'll try and rephrase my question here: https://www.physicsforums.com/threads/why-is-the-electromagnetic-field-not-a-charge-field.857927/#post-5384284 In a way where my ignorance doesn't outrage...
36. Calculating Minimal Distance between Two Protons in Motion

Homework Statement A proton is moving at speed v from infinity toward a second stationary proton, as shown below. Determine the minimal distance between them. http://s27.postimg.org/lmw3d21j7/Untitled.png Homework Equations W = \frac{kq_1q_2}{r} E_k = \frac{mv^2}{2} The Attempt at a...
37. A fixed charge at origin and a moving charge repelled

Homework Statement [/B] A charge of +3.37µC is held fixed at the origin. A second charge of 3.37µC is released from rest at the position (1.15 m, 0.590 m) . (a) If the mass of the second charge is 2.90 g, what is its speed when it moves infinitely far from the origin?(b) At what distance from...
38. [Electromagnetism] Force on a moving charge expression

Homework Statement [/B] The total force on a moving charge q with velocity v is given by \mathbf{F}=q(\mathbf{E}+\mathbf{v}\times\mathbf{B}) Using the scalar and vector potentials, show that \mathbf{F}=q[-\nabla\phi-\frac{d\mathbf{A}}{dt}+\nabla(\mathbf{A}\cdot\mathbf{v})]Homework Equations...
39. Determine the angle through which the moving charge is deflected.

Homework Statement A Particle of mass m and chargeq oves at high speed along the x axis. It is initially near x=-infinity and it ends up near x=+infinity. A second charge Q is fixed at the point x=0, y=-d. As the moving charge passes the stationary chrge, its x component o velocity does not...
40. Does a Magnetic Field Emerge from a Moving Charge with Constant Angular Speed?

If I write the lagrangian for a moving charge with constant angular speed, would a magnetic field be emergent? I would do the math myself, but I'm nowhere near pen and paper.
41. Charge's Frame: Electric Field of Moving Charge

We all know that in the lab frame observing a charge moving along x-axis, we see an electric field ##E = \frac{Q}{4\pi \epsilon_0 x^2\gamma^2}##, picking up an extra factor of ##\gamma^2## at the bottom. Assuming no external fields are present, what would the charge see in its own rest frame...
42. Sketching equipotentials for a moving charge

Homework Statement A point charge remains stationary at the origin for a long time but then, at time t = 0, is displaced, at uniform speed c/2, to a new position R, where it stops. Sketch with care the equipotentials of ##\phi## at a time t = R/c, and then again at time t = 4R/c. Your...
43. Validity of application of Coulomb's Law with moving charge?

Hi there, I'm trying to brush up on some of my E&M and am comparing treatments of Coulomb's Law in introductory calculus-based texts with higher level material. My understanding was that Coulomb's Law (and by extension, calculation of the electrostatic force on a charged particle using F = qE)...
44. Relative Magnetic Fields: What is Reality?

According to page 61 'Einstein' by Andrew Robinson an electric charge at rest produces no magnetic field. But: For an observer moving East with uniform motion the charge will appear to be moving West uniformly and B, using a sensitive compass, will detect a magnetic field around the 'moving'...
45. Four-potential of moving charge

Homework Statement (a) Find the four-vector potential of a moving charge (b) Find source time and z-component of electric field (c) Find electric potential to first order of x and hence electric field[/B] Homework EquationsThe Attempt at a Solution Part(a) [/B] \phi = \frac{q}{4\pi...
46. Do magnetic fields tend to align? (moving charge & other B)

When a moving proton travels through a magnetic field, doe's it's magnetic field (that it's giving off) naturally align with the outside magnetic field (due to a magnet or something in the environment)?
47. Force on moving charge in ELECTRIC field

Homework Statement The diagram shows the path of a charged particle through a uniform electric field, having vertical field lines. (the iamge has been attached) What could give a path of this shape? A a positive charge traveling left to right in a field directed downwards B a positive charge...
48. Electric Charge and Magnetism: Constant or Varying Magnetic Field?

If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
49. Does a Constantly Moving Charge Produce a Constant Magnetic Field?

Homework Statement A charge moving with constant velocity, does it create a constant magnetic field or varying 1?? Homework EquationsThe Attempt at a Solution
50. Maximum magnetic field from moving charge

Looking at the fields that result from a uniformly moving electric charge, derived from the Lienard-Wiechert potentials, you find that an observer at a right angle to the direction of travel will see a magnetic field proportional to ##\beta (1 - \beta^2)## suggesting a maximum field at ##\beta =...