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 ...
- 91
14
votes
7
answers
4k
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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 ...
- 161
0
votes
0
answers
16
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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 \...
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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 ...
- 89
1
vote
2
answers
36
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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 ...
- 117
0
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0
answers
21
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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, ...
- 103
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 ...
- 11
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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 $\vec{F}=q \...
- 959
1
vote
2
answers
120
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How can two observers agree on the force between 2 moving charges?
I'm having a hard time figuring this out. This question has been asked before, I saw the answers, but I'm still struggling with this. So I decided to ask.
I want to calculate the same force for both ...
- 11
3
votes
4
answers
87
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Is the Lorentz force applied to bulk objects?
Assume that a bulk uniformly charged ($+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 ...
- 2,503
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=...
- 33
1
vote
1
answer
132
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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 ...
- 2,456
2
votes
1
answer
292
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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
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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 ...
- 2,503
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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 ...
- 2,327
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 ...
- 23
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votes
1
answer
58
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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 ...
- 25
29
votes
11
answers
6k
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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 ...
- 719
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1
answer
57
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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 ...
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2
answers
165
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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 ...
- 97
0
votes
1
answer
60
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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", ...
- 393
1
vote
2
answers
102
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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 ...
user342647
1
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3
answers
250
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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 ...
- 213
0
votes
1
answer
544
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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 ...
- 137
1
vote
1
answer
205
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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 ...
- 11
1
vote
0
answers
26
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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
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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
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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 ...
- 151
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1
answer
823
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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 ...
- 29k
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?
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