Lorentz force Definition and 193 Threads

David J. Griffiths Introduction to Electrodynamics page 460: Lorentz force equation invariance leads to different Lorentz force values in different inertial frames. Is this a problem for conservation of momentum? More specifically conservation of angular momentum?

I know that the magnitude of the velocity can't change because the only force acting on the charge will be the Lorentz force which does not do any mechanical work. The tricky thing is finding the final angle of the particle. If we try to just imagine how the particle would move, then as it...

Hi! I am developing a fusion reactor simulator and when a proton spins in a perpendicular magnetic field the Lorentz force qv×B is applied at a right angle, however whenever you add a value to a vector in this way its magnitude increases, which contradicts that the velocity of the proton should...

Hi, reading Griffiths - Introduction to Electrodynamics I'm confused about his claims in section 7.1 My point is that the job of electromotive force ##f## is actually produce the "movement/drift" of free charges against the electromagnetic field, so ##f## should not be given by the Lorentz...

If a charged particle moves with velocity V over a perpendicular margnetid feild B then the particle experiences lorentz force F = q(V x B). This force eventually results in what is called circular motion where the magnetic force becomes centripetal. However if the Lorentz force results in...

My question is about item (b). For item (a) we have uniform circular motion in the regions with uniform magnetic field. $$\vec{F}_{B_1}=qv\hat{\theta}_1\times B_1(-\hat{k})=-qv_1B_1\hat{r}_1=-mR_1\theta'^2\hat{r}_1\tag{1}$$ $$B_1=\frac{mv_1}{R_1q}\tag{2}$$ A similar calculation for the...

I know that ##∇(A⋅v)=(A⋅∇)⋅v+(v⋅∇)⋅A+v×(∇×A)+A×(∇×v)## The third term ##v×(∇×A)## simplifies to ##v×B##. I'm just now sure how to "get rid" of the other terms. I tried checking for some vector identities but couldn't make any headways. Any guidance?

Hi. Maxwell's equations tell us how charges and currents act on electric and magnetic fields. However, when we conversely want to investigate how EM fields act charges and currents, we need this very different thing called Lorentz force. This all looks so asymmetric to me because those laws...

Background: is the equation of Lorentz force for the force acting on a moving charge in electric and magnetic field. For the magnetic field only it is : F=qv×B. Question: For magnetic field only why is the force not F=q(v×B) = F=qv×qB

I am searching online for resources regarding studies done on the effect of the Lorentz force due to short circuit faults in capacitors. Although a DC-link capacitor only sees the ripple, there would be high current during a fault. Since F=(qE + JxB), I am curious what the effects of the high...

It is mentioned in the book "Ampere-Neumann Electrodynamics of Metals", Peter Graneau, that Carl Hering in 1923 operated furnaces by passing high current through the molten metal pool. He observed molten metal flow due to the currents. How is the conductor motion explained?

In Q.E.D., the electrical part of the Lorentz Force between unlike and like charged particles is realized through the absorption and emission of photons. How is the magnetic part of the Lorentz Force realized in Q.E.D. via photon activity? As always, thanks in advance.

Suppose the E-field is ##-E_y\hat y##, and B-field is ##B\hat z##. Mass is ##m##. z | |_____x / y ##m(\ddot x \hat x + \ddot y \hat y) = q(-E_y \hat y + (v_x \hat x + v_y \hat y) \times B \hat z)## By grouping terms with ##\hat x## and ##\hat y## together, ##m\ddot x = -qv_yB##...

Here the 3 set of equations we know, the Maxwell Equations, Lorentz Force, and Coulumb Force, actually I doubt a lot what set of equations represent all the electromagnetic aspects, I try research over the internet and I found a lot of contradictions in the answers, someone says we can get the...

So as the summary suggests, I am studying Electromagnetism, magnetic properties of matter and Magnetization vector in particular. As a first example and to introduce the Magnetization vector (M), my textbook shows a ferromagnetic substance in a uniform magnetic field (B). Then, every atom of...

Hello. I am trying to do a basic experiment to demonstrate I⊗β≈ƒ or current cross magnetic field results in a force perpendicular to the plane of the other two. But every time I test this out, it appears I get a force in the same direction as the magnetic field. Here is my experiment: Strong...

Hi guys, I'm being introduced to magnetism, and the direction of the Lorentz force is quite confusing since it's involving a vector product. Which method would you recommend me in order to easily deduce the direction?

I'm trying to understand how the Lorentz force can explain why magnets attract and repel. The explanations that I have found have mostly involved the magnets moving in a way that decreases the forces between them ( ) but I have not been able to find any intuitive explanation involving the...

When deriving the Maxwell Stress tensor, the Lorentz formula is converted from point particle: F=qE+qv x B Into current and charge density: F=ρ E + j x B However an argument can be made that we can't "fieldify" both q and E at one step, and thus, a "coercion" of the field to a value is...

If you take a bar magnet and place a wire with current a short distance from the end, Lorentz's law can be used to accurately predict the location and magnitude of the resulting forces. The same is true if you use a large volume uniform magnetic field to create an induced field in a bar ferrite...

If the mu of the ferrite is high, as suggested, the B field on that section of wire is zero, and therefore there is no force on the wire. Instead there is a comparable force on the ferrite itself. But suppose you allow the ferrite to have different values of mu. If mu=1 the force is just...

A solution of equations of motion for charged particle in a uniform magnetic field are well known (##r = const##, ## \dot{\phi} = const##). But if I tring to solve this equation using only mathematical background (without physical reasoning) I can't do this due to entaglements of variables...

Two charges are moving mutually perpendicular to each other in space with constant velocities. The moment one charge crosses over the line of path of second charge the force on 1st charge (located just behind the 2nd charge moving away from it) appear to be zero (Magnetic field due to 2nd...

I am working on derivation of Lorentz force. (I know that Lorentz force is in some sense definition of fields, but still there is nontrivial dependence on velocity). I want to derive that the force is linear in components of velocity, so for example $$F_x=q(E+Av_x + Bv_y + Cv_z ),$$where ##A...

Hi everyone, in school we recently learned about the Lorentz Force, which says that when charged particles move through an electric field (perpendicular to the field lines), a force is excerted on them (called the Lorentz Force), which goes perpendicular to both the magnetic field lines and the...

I setup an experiment to detect a magnetic field due to the Lorentz force acting on a current. It is a hollow conducting cylinder with a magnet at one end. With current flowing in the cylinder I approach the negative end with the north pole of the magnet. Using the left hand rule I expected the...

Hi. In order to explain the motion of an (accelerating) electromotor, we need the Lorentz force which itself is not one of Maxwell's equations. Conversely, if we use the same electromotor inversely to generate electricity, Faraday's law (which is a Maxwell's equation) and the resistance of the...

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.

Homework Statement Suppose we have an isolated, long, narrow straight wire with low electrical resistivity. A constant current ##I## is sent through this wire. We know that if an electron is sent on a path which is perpendicular to the wire, towards it, with an initial speed ##v_0##, and the...

Homework Statement A proton moves with a speed ##v = 3 \cdot 10^5 \frac{m}{s}## in the parallel direction to ##i+k##. A magnetic field of ##1T##, in the ##i+j+k## acts over it. Which electric field must we apply in this region so that the Lorentz force over the proton is null? Homework...

Magnetic Lorentz force is the force experienced by any charged particle moving in a magnetic field.i want to clarify some doubts regarding this topic of Magnetic Lorentz force.some of them are: 1. Is it the Lorentz force that is actually responsible for the phenomenon of electromagnetic...

What happens to the velocity? Say we have a piece of space debris in free fall. It has a particular velocity at a given time. Then say at some later time it's bombarded with ionic gas or something that causes it to become charged. Does the velocity change? My guess would be yes, because the...

We can find the force by finding the E-field on the charge first, then applying Lorentz force formula. However, it isn't obvious to me at all how to find the E-field. If the charge were on top of the hemisphere I would be using spherical coordinates, but here I don't know which coordinate system...

I need to write a code to calculate the trajectory of the particle under lorentz force.Since the position depended equations are hard to solve I ll use a code, how can I appraoch this problem. I should use veloctiy-verlet algorithm or any suggestions ? You should consider that lorentz force is a...

Homework Statement Solve the Lorentz Force Equation (Find ##\vec{r}(t)##) under constant ##\vec {B}## and ##\vec {E}##. İnitial Velocity: ##\vec{v_i}=<0,0,0>## İnitial position: ##\vec{r_i}=<0,0,0>## (##\vec {B}## and ##\vec {E}## are given values) Homework Equations Lorentz Force: ##\vec...

Lorentz transformation of electromagnetic field gives the relation ##E'=\gamma(E+v\times B)##. Lorentz force per unit charge is given as ##F=E+v\times B## without ##\gamma##. Don't we need coefficient ##\gamma## for F?

I have a picture below please have a look at it. The guy is using two conducting rods placed parallel to each other and placed below it are magnets. When battey is connected to rods and a conductor is placed over them it starts to move.That works according to flemmings left hand rule. I was...

I'm not sure if this belongs in special/general relativity or in this subforum. I'm currently trying to refresh and strengthen my E&M, and I remembered that one thing that bugged me when I first learned about magnetism was the velocity in the Lorentz force, $$\vec{F} = q\vec{v} \times...

Hello all, I've been pondering a problem with a current carrying wire in a magnetic field. The Lorentz force is easy, ILB, with a velocity 90 degrees to the B field. So let the force accelerate the wire. Assume only one segment of the wire that has current in one direction, say up, is in the...

Homework Statement The Lorentz Force can be used to sort ions (atomic or molecular) based on their charge to mass ratio. This configuration has been used to separate isotopes and as a mass spectrometer. A beam of Strontium ions Sr+ is accelerated through a potential of 500 V and injected into...

I've dissected several hard disk drives to scavenge the "linear" motors which move the read-write heads across the disk platens. At first glance these look simple enough. There is a pair of high energy permanent magnets in a yoke which provide a circular sector shaped high magnetic field in a...

We know that Lorentz Force is a centripetal force so: $$qVBsenx=m\frac{v^2}{r}$$ and the value of V is constant (but not the direction) But if we write: $$qvBsenx=m\frac{dV}{dt}$$ we obtain that v is exponential. What is wrong ?

Homework Statement Particles of mass ##m## and charge ##q## are initially traveling in a beam along the ##z## direction with speed ##v## when they enter a long magnetic quadrupole lens, where there is no E-field and the magnetic flux density is ##B = Ay\hat{i} + Ax\hat{j}##, and where A is a...

A current loop has a wire starting at its center. The wire terminates at the inside of the loop. The loop and wire have 150 and 15 ohms of resistance respectively. Both have 4 volts of potential across them. Looking at this I understand the the wire will experience a lorentz force because the...

Let's say I have a charge q which is viewed from its rest frame. So it's velocity v is 0. So the so-called magnetic component of its Lorentz force, which is q v x B, is 0. But I can have a magnet moving in this frame of reference. Let's say the velocity of this magnet according to the charge's...

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...

In Jackson, the following equations for the vector potential, magnetostatic force and torque are derived##\mathbf{m} = \frac{1}{{2}} \int \mathbf{x}' \times \mathbf{J}(\mathbf{x}') d^3 x'## ##\mathbf{A} = \frac{\mu_0}{4\pi} \frac{\mathbf{m} \times \mathbf{x}}{\left\lvert {\mathbf{x}}...

Homework Statement Hi everybody! I am struggling with an old exam problem, could someone maybe help me out to figure it out? Here is how it goes: A rod with resistance ##R = 0.1 \Omega## lays over two parallel tracks (resistance ##\approx 0 \Omega##, ##l=10##cm). A battery is connected...

Homework Statement Show that the Lorentz Force Law, \frac{dp^{\nu}}{d \tau} = -q U_{\mu} F^{\mu \nu}, is consistent with P^\mu P_\mu= -m^2. Here U is the 4-velocity, F is the Electromagnetic Tensor, and p is the 4-momentum. (Minkowski Space) Homework Equations As stated above. The Attempt at...

I have some confusion about the Lorentz force. First of all, I found that there are two equations for the Lorentz force: one of them is F = qE + qv × B , and the other one is just F = qv × B . What's the difference between them and how do you know which one to use? My other question is: Is the...