All Questions
144
questions
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47
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What happens when both magnetic field and electric field is applied to a charged particle?
Now what exactly happens when magnetic field and electric field is applied perpendicularly? What happens when they are not perpendicular?
In the question, it says that a magnetic field and electric ...
14
votes
7
answers
4k
views
Why does a charge need to have a velocity to experience force in a magnetic field?
While studying magnetism, I learned that force on a charged particle inside a magnetic field is
$$\mathbf{F}=q(\mathbf{v}\times\mathbf{B})$$
where all symbols have their usual meaning, which implies ...
0
votes
0
answers
16
views
What is the physical meaning of the torque term involving the magnetic displacement force?
In Zangwill's Modern Electrodynamics the magnetic torque is derived in Eq. 12.63 to be
\begin{equation}
\mathbf{N}(\mathbf{r}_0) = \mathbf{m} \times \mathbf{B}(\mathbf{r}_0) + \mathbf{r}_0 \times \...
0
votes
0
answers
28
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Force on an iron ball in a homogeneous magnetic field [duplicate]
Just a simple question. If I have a homogeneous magnetic field and I put an iron ball into this field, it would be attracted to the source of the magnetic field. But how do I calculate the force that ...
1
vote
2
answers
36
views
Force between two current carrying conductors
lets say I have two wires. each has a magnetic field due to its current. this magnetic field is present in the other wire causing a force in that other wire. Now I understand that changing the current ...
0
votes
0
answers
21
views
Maximum force of a metal ball going trough coil
I've been trying to figure out the maximum force of a metal ball going trough a coil.
I have:
$$ m=\chi_m V B \qquad B=N \mu_0 I R^2 \frac{1}{2(x^2+R^2)^{3/2}} $$
Also that $F=(m\cdot B)'$. However, ...
1
vote
1
answer
35
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Getting the force somehow using magneticfield force (tesla)
First off, sorry if not everything makes sense, english isn't my first language so some scientific terms may sound weird if they're in English. For a project we are making a coil gun. So we get a ...
0
votes
1
answer
85
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The magnetic force is conservative when the magnetic field is static, what is its potential function then?
The magnetic force $\vec{F}$ can be conservative when the magnetic field is a static. That is $\vec{\nabla} \times \vec{F}=0$, so it follows that there is a scalar function $f$ such that $\vec{F}=q \...
1
vote
2
answers
120
views
How can two observers agree on the force between 2 moving charges?
I'm having a hard time figuring this out. This question has been asked before, I saw the answers, but I'm still struggling with this. So I decided to ask.
I want to calculate the same force for both ...
3
votes
4
answers
87
views
Is the Lorentz force applied to bulk objects?
Assume that a bulk uniformly charged ($+Q$) nonconductive sphere is set in motion inside a uniform magnetic field. Is it correct to claim that the trajectory of the bulk sphere inside the magnetic ...
1
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4
answers
208
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What's the difference between $f= i (l × B)$ and $f= (i∫dl )× B$?
for any current carrying conductor of any arbitrary shape in uniform magnetic field experiences a force given by F = i (l × B) where l is length between end and start points of the conductor and in f=...
1
vote
1
answer
132
views
Ratio between electric and magnetic forces
Suppose I have two beams of electrons moving at speed $v$ separated by a distance $d$. I can work out magnetic and electric forces between them...
For the magnetic force, we treat the two beams wires ...
2
votes
1
answer
292
views
Can a current carrying loop experience force due to its own magnetic field?
In my opinion, the wire must expand due to the magnetic force acting radially outwards on two diametrically opposite ends of the loop as a result of the equation:
F = I(dl × B)
Where B is the ...
-1
votes
2
answers
260
views
U-shaped magnet and the moving charge: Where is the origin of the Lorentz force from the viewpoint of the moving charge?
Assume that a charge $+q$ is located at rest between the poles of an infinitely long U-shaped magnet, which is laid along the $x$-axis. If the charge slowly accelerates to a velocity $v$ along $x$ and ...
0
votes
0
answers
49
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If magnetic force is perpendicular to the direction of motion, does that mean the direction of motion prior to the magnetic force doing anything?
I want to make sure I'm understanding this correctly:
My understanding is that magnetic force can do no work because it can never change the speed of an object -- instead it can only cause ...
1
vote
1
answer
116
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Magnetic force calculation for parallel wires using Maxwell stress tensor. Issue with shear forces
I am trying to calculate the forces in between permanent magnets and ferromagnetic surfaces with the Maxwell stress tensor using image theory and the Biot-Savart law. However I discovered a weird ...
0
votes
1
answer
58
views
Why the magnet travels through solenoid faster if we connect a bulb to a solenoid
When a magnet travels linearly through a solenoid at a fast enough velocity if the ends of solenoid are connected to each other, the induced EMF generated and Lenz Law the solenoid opposes the motion ...
29
votes
11
answers
6k
views
Is there a more "physically mature" way to think about the right hand rule with electromagnetism?
I've always found using the righthand rule to remember how forces, B-fields, and particle velocities to be intellectually cheating myself a bit. It feels like being able to multiply numbers by using ...
0
votes
1
answer
57
views
Does a levitating Superconductor experience reistance to motion from the magnetic field if a force is applied?
If one has a superconductor that's being levitated on a track and you apply a force through its c.m. completely parallel to the track it's on (perpendicular to gravity), would there be any kind of ...
0
votes
2
answers
166
views
Is force perpendicular to magnetic field in a bar magnet?
Recently I started this topic. My lecturer used
$$F_{B}=q_{n}B$$
I have two questions in this topic.
By this equation both the magnetic field and Force are in same direction. But aren't they supposed ...
0
votes
1
answer
60
views
Can a net propulsive effect occur between phase shifted antennae?
So this question centers around an electromagnetic thought experiment suggested by the patent titled "Efficient RF electromagnetic propulsion system with communications capability", ...
1
vote
2
answers
102
views
Does the force between two magnetic poles ever reach zero?
If we hold two magnetic like-poles together and start to move them away, would the repelling force reach absolute zero at certain point?
In that scenario, as a layman, I think that there is something ...
1
vote
3
answers
250
views
Why is the cross product used in electrodynamics [closed]
For example, $F = I \times B$. Why would the force be perpendicular to both the magnetic field and the current? Why would the resultant force be totally unlike its 2 sources; this could be likened to ...
0
votes
1
answer
544
views
Formula for Force between two Solenoids
Given two identical solenoids (with appropriate core) $S_0$ and $S_1$ with length=$L$, radius=$R$, number of turns per unit length=$n$. Let these two solenoids be held with the two poles facing each ...
1
vote
1
answer
205
views
Force acting on a negative particle in a magnetic field
I have recently learned about magnetic fields and particles. The recent one I have learnt is the right hand rule. The force F acting on a negative particle is always opposite to the force we get from ...
1
vote
0
answers
26
views
Why does a magnet arranged in a magnetic accelerator propogate a wheel forward?
My question is related to an interesting video i saw on magnets. The link of the video is here https://youtu.be/iyv9GhaITNE , in this video at 1:52 of the video we see the wheel is moved forward but i ...
0
votes
1
answer
226
views
Doubt regarding $ F = BQv \sin \theta$
In $ F = BQv \sin \theta$, is $v$ velocity acquired by charged particle after entering magnetic field or is it already moving with $v$ m/s and $F$ force acts on it after it enters magnetic field?
1
vote
1
answer
92
views
Magnet A exerts an magnetic force $F_1$ on magnet B, B exerts a Reactive force $R_1$ on A, B exerts an magnetic force $F_2$ on A, is $R_1=F_2$?
Let's suppose there are 2 magnets, A and B, that are within the magnetic field of each other. Then A will exert a magnetic force on B (let's name it F1), and, due to the 3rd law of Newton, every ...
0
votes
1
answer
823
views
Can magnets really repel water (liquids) like this?
I have read this question:
However, in a small number of solids the outermost electrons of the atoms line up parallel with each other and their magnetic moments reinforce each other to give the solid ...
3
votes
3
answers
398
views
Detect reaction force to Lorentz force
If a charged particle is deflected in a magnetic field due to some magnet, is there any experiment that shows (or measures) the opposite reaction force (due to Newton's third law) on the magnet?
0
votes
1
answer
111
views
Direction of magnetic force
Does magnetic force act along the line joining the centres like gravitational and electric forces do?
Are the directions of magnetic field and magnetic lines of force the same? I have read that the ...
-2
votes
0
answers
71
views
Magnetic force is pseudo? [duplicate]
Is magnetic force pseudo
Magnetic force exist only if charge is moving , so it must be pseudo . Imagine , a positively charged man who has the same speed as electron (charge). So , he doesn't feel any ...
-2
votes
3
answers
404
views
Is magnetic force pseudo?
Is magnetic force pseudo
Magnetic force exist only if charge is moving, so it must be pseudo.
Imagine, a positively charged man who has the same speed as electron (charge). So, he doesn't feel any ...
0
votes
1
answer
59
views
How to calculate the force applied by a magnetorquer on a piece of a perfect ferromagnetic material?
Magnetorquer are 3 axis electromagnets used in satellites for attitude control using Earth's magnetic field. How to calculate the force applied by a magnetorquer on a piece of a perfect ferromagnetic ...
1
vote
1
answer
246
views
What direction does magnetic dipole moment feel force in parallel magnetic field?
Suppose I have a magnetic dipole oriented vertically in the $\hat{z}$ direction so
$$ \vec{m} = m\hat{z}$$
And the position vector to it is $\vec{r} = z\hat{z}$. It's entirely on the z-axis.
We're ...
0
votes
0
answers
366
views
Magnet layout to maximize magnetic attraction along entire surface
We want to use permanent magnets to attract iron filings. For this, we have several neodynium magnets shaped as disks and we would like to lay them out to have the highest possible attraction along ...
0
votes
1
answer
55
views
Is there a mathematical limit to the summation of infinitesimal magnetic and electric field in the Lorentz Force?
The addition of infinitesimally small parallel electric and magnetc fields, irrespective of their origin or source, or physical feasibilty; seems to produce a seemingly impossibly large force. Or at ...
1
vote
3
answers
124
views
Is it possible to create a magnetic environment where it pushes and pulls at the same time, making the target “levitate”?
To better understand why I ask this, the backstory is I’m getting more and more annoyed by rolling office chairs rotating, hitting my ankles, hard to switch directions when wheels having ~90 degrees ...
1
vote
1
answer
287
views
How can I determine a direction of force which is made by magnetic field and current with a wire? Fleming left hand rule seemingly not works at here
Please assume that the conductor of wire exists , and the current flows from below left to above right like shown in the above diagram.
As shown in the above diagram , the uniform magnetic fields are ...
1
vote
0
answers
37
views
Does the Lorentz force change when an electric current is under a magnetic field with negative permeability?
Most applications of the Lorentz force depend on the electric current passing by a material with positive permeability, normally ferromagnetic.
How much would change were the electric current to pass ...
0
votes
1
answer
91
views
How to calculate/understand the Lorentz force of a continueous charge distribution
I know that the Lorentz force formula is $$F=\iiint \rho(E+J\times B)dV$$ for continuous charge distribution. But is E the electric field that creates the current (density) J, or this is another ...
0
votes
1
answer
161
views
Tesla to Newtons Over Given Distance
I have a Neodymium magnet, for example, that has a magnetic flux density of $1.25 \;\text{T}$ and is 1 inch by 1 inch by 0.44 inches. I have a steel ball with a diameter of 0.5 inches placed 3 inches ...
0
votes
1
answer
181
views
Lorentz force on objects
I've been learning about electromagnetism and recently saw the Lorentz Equation. I have questions that keeps bothering me and I could not figure it out by myself.
So when we put two different poles ...
1
vote
4
answers
568
views
Why isn't the magnetic field defined by the magnetic force on a particle moving through it?
A magnetic field describes the influence a charge (in motion) experiences. In other words, it is essentially a vector field that describes the force that a particle will feel at a given location. ...
0
votes
1
answer
977
views
Force on a current carrying loop in a non-uniform magnetic field
I was taught that a current carrying loop in a non-uniform magnetic field will always experience both a torque and a net force.
Is this always true? I can't think of any examples where the force would ...
1
vote
1
answer
159
views
Electric field on test charge due to dipole
In worked example 4.1 of Intermolecular and Surface Forces by Jacob Israelachvili, he is calculating the electric field on a test charge due to the dipole shown in the picture.
He assumes $r\gg l$ and:...
0
votes
2
answers
187
views
Electromagnetic force at a distance
Is it possible for an electromagnet of around 50mm diameter to produce a force of 1000N at 10mm distance far away ferromagnetic object (air between them) ? If yes, how much power (approx) will it need ...
1
vote
1
answer
37
views
Can you induce motion by changing magnetic field on a body which isn't magnetic?
In this video demonstration of Lenz's law, the narrator starts with a substance which doesn't respond to the magnetic field of a bar magnet yet when he moves the bar magnet in relative motion to the ...
1
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3
answers
955
views
Why is force on a circular current carrying wire zero?
I have a very silly doubt, and it's bothering me. Magnetic Force because of a line current is:
$$\mathbf{F_{mag}} = I\int\mathrm{d}\mathbf{l\times B}$$
However, in a constant magnetic field, for ...
0
votes
1
answer
64
views
Magnetic force on a stationary body
A charged particle near a current-carrying wire does not experience a magnetic force when its velocity is equal to $0$. So why does a compass needle kept near a current carrying wire experience a ...