Magnetic force Definition and 398 Threads

Suppose a charge is moving towards another charge at rest. At a given instant of time, The electrostatic force applied by either charge on the other is same, but only one is applying magnetic force on the other. Doesn't this violate Newton's third law?

Hello everyone, I try to calculate brake force for primitive eddy current brake, but I have problem with determining the frequency (skin depth) and characteristic length (magnetic Reynolds number). I attach the equations and a scheme of the model.

If you have many free electrons forming a cloud they wouldn't last too much as they would be repelled from each other due to electromagnetic forces. Gravity wouldn't help since it is much weaker than electromagnetic force, so electrons would still fly away However, can they be stabililized by...

Hi, I am struggling to get the right answer for this question. My first thought was that I should consider to what direction does each segment of wire have a force towards. I found the direction to be in the following (see red arrows): My past attempt was: Floop = [FONT=book...

This answer is incorrect when I try submitting it.

these notes on magnetic field from MIT OCW's 8.02 course. There is the following snippet on page 10 At this point it is still not clear to me exactly what a magnetic dipole is. I've done all the calculations for a current-carrying rectangular loop, so I will assume that a magnetic dipole is...

Question: Can we ultimately atttribute no work or net zero work done by a magnetic force to the closed magnetic field lines that results in Divergence zero of a magnetic field? That is, is it a misconception to say that closed magnetic field lines imply magnetic force will always result in no...

I know the easier method/trick to solve this which doesn't require integration. Since parabola is symmetric about x-axis and direction of current flow is opposite, vertical components of force are cancelled and a net effective length of AB may be considered then ##F=2(4)(L_{AB})=32\hat i##...

I'm looking for calculation for proportional solenoid force (constant force for some working stroke) using magnetic reluctance based on equivalent magnetic circuit by networking method. I was reading a book Elektromangnate by Dr Kallenbach which discussed such method but for switching solenoid...

A current carrying conductor experiences magnetic force in a magnetic field. F=BILsinθ Where, B = Magnetic flux density I = Current L = Length of conductor and θ = Angle between magnetic field and current This force is due to free electrons moving in a...

The situation is as follows. We have two disk magnets. One is fixed on the ground, table, or surface and has the north pole facing up. Then we have a metal plate fixed on the vertical axis rod or something similar such that it can't move up or down, but only rotate horizontally with as less...

I am getting a wrong answer for part b, however part a and c both are correct : a. 0 N b = -2.91E-3 N (WRONG) c. 1.4E-4 N

so with a Hall Voltage, you have positive current traveling upwards in a wire in the +y-direction and a magnetic field into the screen in the -z-direction. the right hand rule has positive charge deflecting to the left. now if you look at the drift velocity of electrons moving downward in the...

I understand the iron fillings become little magnets all pointing in the same north south direction similar to the spin aligned electrons in the permanent magnet. Similarly, a compass near a wire traces out the magnetic field lines ie North/South. My question is how do I reconcile the fact that...

I am having problems understanding point (b) so I would like to know if my reasoning in that part is correct and/or how to think about that part because I don't see how to justify the assumption ##v_y=0\ m/s##. Thanks. I set up the ##xyz## coordinates system in the usual way with ##xy## in the...

d(ɣmv)/dt = qvB (dɣ/dt)mv + ɣm(dv/dt) = qvB Substituting gamma in and using the chain rule, it ends up simplifying to the following: ɣ^3*m(dv/dt) = qvB Now, I am confused on how to solve for v.

Plug in the elementary charge for q, 1000 m/s for v, 50 microtesla for B and 90 degrees for theta and I get about 8e-21 Netwons. But apparently this is wrong, anyone know why? Thank you.

So I'm familiar with the magnet falling through a copper tube demonstration that shows the induced magnetic fields slowing the magnet down. I know that this experiment is also possible with a conducting coil as long as the coil forms a closed circuit. I'm trying to find a way to calculate the...

How can I calculate the force from magnetic field of a solenoid, grabbing a small iron ball? I want to use the good old simple F=ma formula in order to calculate the ball's acceleration. But can't find a formula to somehow convert the known field quality (in unit Tesla) to Force (in unit...

Hi, The problem I am working on requires me to work out the the pressure on the outer conductor of a coaxial cable due to the current on the inner one. This cable carries a dc current of 5000 Amps on the inner wire of radius 2 cm. The outer cylindrical wire of radius 5cm carries the return...

Hello, In the section of Magnetic Force on a Current- Carrying Conductor in the book of College Physics by Serway, it is written that the Current- Carrying Conductor in a magnetic field deflects because the magnetic force on the electrons transfers to the bulk of the wire due to the collisions...

a) On QP, the force is zero. On PR, the force is directed inside the plane, and its magnitude is ##0.8IB##. On QR, the force is direction out of the plane, and its magnitude is ##1IB\sin(\arctan(0.8/0.6))=0.8IB##. b) ##0.8IB-0.8IB=0##. d) It will rotate outside of the page. c) I know that the...

Hello! The magnetic force is to the right. ##I_c## is the moment of inertia of the cylinder. For the net force on the centre of mass, I have the frictional and magnetic forces ##F=F_B-f##. I know that ##F_B## is ##IdB##. I also know that ##rf=I_c\alpha=I_c\frac ar##, so that...

Surely a tough one, I am doing it from the basics. This is the diagram i tried to draw showing the Force and current I The Length L is the tangent to the circle. The Force F is pointing upwards at ##90 Deg## to the ##\vec B## and also perpendicular to ##\vec L##. I am considering a small...

The beam of protons are directed towards the axis of the cylinder, perpendicular to the direction of the field. While traveling through the cross-section of the cylinder, the proton beam experiences a magnetic force, which tends to move the beam in a circular orbit of the radius given by: r =...

Consider a coil perpendicular to the ground falling with gravity. Under it, there is a magnetic field also perpendicular to the coil. When the coil starts penetrating the magnetic field there will be an induced current and therefore a magnetic force upwards. This magnetic force will reduce...

Since the magnetic field is pointing down, I can derive that the magnetic force is into the page. With this, I can't really imagine how the particle can move in a circular motion as I cannot visualise how the centripetal force will look like when the force is into the page (instead of usual...

I'm not so sure how to begin with this problem. I was thinking of usign superposition. I think that the field on the conductor due to the parallel segments of the coil is zero, since Ampere's Law tells us that the field outside the solenoid is zero, right? For the perpendicular segments, I used...

How can I measure the levitation forces between the magnets and a type-II superconductor (YBCO superconductor)?

In a paper I am reading, it reads, "For these orbits the electric force ##-e E_r## almost balances the magnetic force ##-e \left ( v/c \right ) H_0##." where ##-e## is the charge of the electrons, ##v## is the speed of the electrons, ##H_0## is a homogeneous magnetic field, and ##c## is not...

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This is how I visualize the problem (of course I am drawing this as if it is in the z-y axis); I don't know what will be the next step. Anyone please help me. Thank you

8000 0 0 5 -4 3 F = (5 x 10^-6) * up (sorry can't write a materix here) F = (5 x10^-6) {0i - 24000 j - 32000 k) F = -0.12 j - 0.16 k Mag of F = 0.2 (I feel that there is something wrong in the question; I don't know)

I just need to confirm my intuition that the magnetic force on the wire carrying I2 is 0. Basis for my intuition: * Right above the center of the loop carrying I1, the magnetic field lines are in exactly the same direction as the piece of wire carrying I2, so [a] x [B1] = 0. (photo from...

Let's say we have a wire and a circuit is closed the magnetic field start to spread with speed of light c. Then we would have a place " out of range " at which the magnetic field doesn't exist.What is the equation that connects magnetic force with distance with its prorogation of speed of light...

Does the metal being attracted make a difference? How would you find the force on the metal knowing the field strength there? How would you even calculate the field strength of an electromagnet with a core? In my case, it is one of those junkyard electromagnets. thanks

I am writing about the nature of force in classical mechanics and what does really imply, in terms of change in motion. I am using as an example a circuit, on which we exert a force. I am trying to justify the following scheme (concretely, ##f_{mag}##): The thing is that I am wondering how...

(a) Let's say the loop has fallen ##y## from its initial position. Then the magnetic flux is ##B_{0}w(h-y)## and the induced voltage is ##\mathcal{E}=B_{0}wdy/dt##. Since this voltage is positive, the current flows clockwise. (b) ##I=\frac{\mathcal{E}}{R}=\frac{B_{0}wv}{R}## (c) The force on...

Homework Statement A proton moves through a uniform magnetic field given by B=(13.7i−22.9j+23.5k) mT. at time t1 v=(vxi +vyj+1.68k)km/s and the magnetic force is given by F= (4.22e-17i + 2.52e-17j). What are vx and vy Homework Equations F=q(v x B) The Attempt at a Solution First I converted...

I have a question for my E&M assignment (I'm not putting it in the homework thread since I just need more of a concept check) that involves a straight wire with current through it. If you have a wire with a current through it, and you have a rectangular wire also with current, to the right of...

When the two current carrying wires (with identical current directions) attract each other, it seems that the magnetic field of wires do work while we know that magnetic force is perpendicular to the velocity of charge. I would like to know whether the the two wires get closer or not? What about...

Can someone provide me with some original experiments conducted which verified the Lorentz magnetic force : F = q(v X B). Google does not give me any links except to explanations of the Lorentz force law.

Dear helpers, I working on an projekt for the University and for that I have to calculate forces between different magnets. The question that I have is: "Is there a way to calculate the force between two magnets if one is completely known and the other unkown. But you know the B-field of the...

Homework Statement The question askes about the path of the electron. I need to know if I am doing it correctly whether it was asked for a proton or an electron. Homework Equations F=QV⊥Bsinθ The Attempt at a Solution I answered it C. Because it is an electron, I used my left hand. My thumb...

Firstly, please note that I am talking about the period BEFORE electricity and magnetism were unified. So I am NOT seeking for answers based on Ampere atomic current model of magnets. I have read the following statement about the property of magnets at two different places. One from here: and...

Hi all, Not a question about completing homework here, but I'm a teacher looking to create a realistic engineering question for an assignment. I have an engineering scenario I've set for the assignment which is a junior engineer working for a marine engineering company so all of the questions...

Homework Statement Two straight rods 60 cm long and 2.0 mm apart in a current balance carry currents of 18 A each in opposite directions. What mass must be placed on the upper rod to balance the magnetic force of repulsion? ## \mu_0 = 4 \pi * 10^-7 ~\frac {T * M} {A}## ## g = 9.81 ~m/s ##...

1. The problem statement, all variables, and given/known data Assume the Earth’s magnetic field is 52.0 mT northward at 60.08 below the horizontal in Atlanta, Georgia. A tube in a neon sign stretches between two diagonally opposite corners of a shop window—which lies in a north-south vertical...

Homework Statement A rod of mass 0.720 kg and radius 6.00 cm rests on two parallel rails that are d=12.0 cm apart and L=45.0 cm long. The rod carries a current of I=48.0 A in a direction that makes it rolls along the rails without slipping. A uniform magnetic field of magnitude 0.240 T is...

<Moderator's note: Moved from a technical forum and thus no template.> So there was this question An electron that has velocity (2*10^6 i +3*10^6 j)m/s moves through the uniform magnetic field (0.03 i - 0.15 j) T (a) Find the force on the electron due to the magnetic field. (b) Repeat your...