All Questions
Tagged with electromagnetism forces
524
questions
26
votes
14
answers
4k
views
Explaining how we cannot account for changing acceleration questions without calculus
For context, I am a high school physics teacher.
I am teaching students about the basics of electromagnetic force between two point charges. The equation we use is $F=\frac{kq_1q_2}{r^2}$.
This gives ...
0
votes
0
answers
24
views
Cgs to Si with Force
So i just have a Problem with the transition from Cgs to SI. I want to Calculate the Force of the Plates of a Capacitor. The Formula is the following:(k=1,2,3 and Einstein Notation is used and T is ...
- 381
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 ...
- 11
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
0
answers
152
views
How friction, tension, spring forces are derived forces from electromagnetic force?
I always imagined friction force causing due to some irregularities in the plane like this,
but lately I am having a hard time thinking "How it is a derived force from electromagnetic force?&...
- 15
0
votes
2
answers
100
views
Inverse relationship data not producing a constant
This is a high school question, so apologies if it's dumb.
I have data from an experiment in which I placed two vertically aligned bar magnets ($N$ to $S$) at various distances, with the bottom one ...
- 3
1
vote
1
answer
390
views
Alternative way of deriving the Abraham Lorentz force equation?
In Griffiths ("Introduction to Electrodynamics"), he motivates the Abraham Lorentz force (i.e. the radiation reaction force) by considering the energy emitted by a particle due to radiation ...
- 115
2
votes
1
answer
46
views
Force on electric charge
What would the force on an electric charge in some ponderable media be, if the electric field due to the charge is not negligible compared to some external electric and magnetic field. I feel like it ...
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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 ...
- 256
3
votes
0
answers
62
views
Why we can stand on the floor? [duplicate]
Feynman (Volume 1, 38-4) seems to explain the normal force of a floor acting on a table as quantum mechanical, arising from the Pauli Exclusion Principle and also, the Heisenberg Uncertainty Principle....
- 1,548
1
vote
0
answers
21
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Force on a moving charge in front of an infinite conducting wall
Let's say we have a charge $q$ at position $\vec{x}=(x_0,y_0,z_0)$ in front of an infinite conducting wall at $z=0$. If the charge is not moving, this problem can be easily solved by the method of ...
- 4,827
0
votes
1
answer
71
views
Do all forces of nature produce opposite force when they move?
I am not sure if I understand it right but as I see it any two moving charge particles must repel each other like they are not moving relative to observer that moving at the same speed as they moving,
...
- 149
1
vote
2
answers
192
views
How does interaction between forces work in special relativity?
Assume a capacitor where upper/lower plate has negative/positive charge. An 1D spring is attached to lower plate, and the bottom of spring is connected to ground. At the beginning everything is at the ...
- 1,350
0
votes
1
answer
1k
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Electromagnet with a hollow core [closed]
For a project, i want an electromagnet with a hollow cylindrical space of 60mm(something Iike as shown in attached image) which can produce a force of 1000N inside this hollow space on a ferromagnetic ...
- 19
0
votes
1
answer
27
views
Is the charge static or not and which field does it apply to in the Lorentz force?
Is it on a static charge on a magno-ecletric field? or on a moving charge on an electric field only or magnetic field only?
Thanks in Advance!
- 3
0
votes
1
answer
779
views
Calculating force on charges using Maxwell stress tensor
In Griffiths' Introduction to electrodynamics, chapter 8.2.2, if you want to calculate the force on charge bounded by V volume, it is said to choose an area that encloses that volume (surface area of ...
- 1
1
vote
1
answer
159
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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:...
- 261
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 ...
- 19
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 ...
- 7,980
0
votes
2
answers
102
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Do closed line integrals need to be evaluated in "the line's" rest frame?
I've seen it said that the definition of emf requires that the integral be carried out in the circuit's rest frame.
\begin{equation*}
\mathcal{E} =\oint \mathbf{f} \cdotp d\mathbf{l}
\end{equation*}
...
- 15
1
vote
2
answers
278
views
Magnetic dipole moment because of spinning electron
We always consider only the spin of electron. But protons are spinning charges as well. So what about the magnetic dipole moment caused by them?
- 453
1
vote
3
answers
954
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 ...
- 453
0
votes
1
answer
94
views
Where can pressure gradient force be classified?
I know that there are four fundamental forces of nature, and they govern everything that happens in the universe. And all the forces which we experience is one among them. But I could not figure out ...
0
votes
1
answer
24
views
Increase force exerted by a body's weight using electricity
I would like to ask if there is any mechanism that can increase the weight force of a body using electricity. For example, this mechanism is enclosed in a box which normally weighs 1kg but when ...
1
vote
0
answers
47
views
Unstable Equilibrium of hinged rods
I conjured up a scenario where there are two rods free to rotate about a hinge connected by their ends by spring of spring constant $k$,both their masses are $m$ and length $l$ and mass is uniformly ...
3
votes
3
answers
149
views
Shouldn't We modify the field in force equation $\mathbf{F}=q\mathbf{E}$?
Consider charge particle $q$ in electric field $\mathbf{E}$. The force on the charge is given by
$$\mathbf{F}=q\mathbf{E}$$
Now we know that charge $q$ will also produce an electric field. Due to this ...
- 11.9k
1
vote
1
answer
200
views
Generalised Lorentz force expression from Classical Mechanics by Goldstein
I am reading chapter 7 in the 3rd edition of Goldstein's Classical mechanics textbook and the expression for the Lorentz force is confusing me. I cannot scan it so I am just going to write it out ...
5
votes
1
answer
642
views
What is the mechanism that causes forces to get unified at high energies?
There are a lot of questions and answers on this site about the unification of forces, and all of them univocally say that at high energy levels, all the forces get unified. But none of them answer my ...
- 29k
0
votes
1
answer
157
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Follow-up on "Derivation of Lagrangian of electromagnetic field from Lorentz force"
I have a follow-up on this post. The way I understand it, if one generally has a velocity-dependent potential $U(q, \dot q, t)$, then we can derive/define a generalized force $$Q_k = \frac{d}{dt}\frac{...
user248824
2
votes
2
answers
932
views
How is force transmitted across a body?
So I am leaning about various topics like physics like simple machines, center of mass, momentum, energy conservation, equilibrium but the more I study these "upper" level concepts the more ...
- 823
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 ...
0
votes
4
answers
1k
views
How to calculate the Force (in Newtons) produced by a solenoid?
How would I calculate the force on an object (in Newtons) that is under the influence of an electromagnetic field produced from a solenoid? I know it would involve using the equation $B=(μNI)/L$ to ...
1
vote
6
answers
253
views
If gravity were a "real" force, then how would I be able to tell if I'm falling or accelerating in space or on Earth?
Background:
I think it would be helpful for laypersons like myself to understand how, in practice, a "real" force differs from a pseudo-force. Virtually all explanations (eg, on this stack, ...
- 121
0
votes
0
answers
147
views
At what height does water need to fall to produce negative ions?
Research shows that waterfalls and apparently showers produce negative ions, is there a certain height or velocity for water to fall to produce negative ions?
- 17
0
votes
1
answer
74
views
Invisible Coilgun Propagation
Forgive me in advance for not being 100% accurate in my explanation. I am not an electrical engineer, nor have I academically studied physics, algebra, or anything of the sort.
So without further ado:
...
- 136
1
vote
1
answer
64
views
Contradiction in Faraday's law and Motional EMF
Consider two parallel conducting frictionless rails in a gravity free rails parallel to x axis. A movable conductor PQ( y direction) of length $l$ slides on those rails. The rails are also connected ...
- 517
0
votes
0
answers
34
views
Why doesn't a conducting wire in a constant magnetic field experience a force in the direction of the magnetic field?
Instead of using the wire's magnetic field for deriving using Newton's third law can't we do the opposite using the magnetic field produced by magnet ?
I mean why doesn't the wire simply move in the ...
1
vote
1
answer
167
views
Movement of Particle in Electromagnetic Field
I'm a high schooler who just finished learning Maxwell's Equations. I'm trying to visualize the movement of a charged particle in a field.
I have an infinite sheet of positive charge oriented on the ...
- 313
6
votes
4
answers
224
views
Action-reaction pairs with electromagnetic waves
Suppose that a tower is releasing radio waves. These waves are received by an antenna. The radio waves apply force to the electrons in the antenna. My question is that by newton's third law, every ...
- 71
3
votes
3
answers
793
views
Lorentz Force on a Current Carrying Wire
Does the Lorentz Force on a Current Carrying wire given by the equation
$$\mathbf{F} = I \int \text{d}\ell \times \mathbf{B}$$
constitute an action reaction pair? That is, if i have two arbitrarily ...
0
votes
1
answer
178
views
Derivation of $F=πB\sin θ$?
I was searching for a formula for the magnetic force on a current-carrying conductor, and though I am accustomed to the formula $$F=IlB\sin θ$$ where $I=$ current, $l=$ length of conductor, $B=$ ...
- 3
0
votes
1
answer
314
views
Newton's third law between moving charge and stationary charge
Between two stationary charges, Newton's third law holds. But what if one of the charge is moving? Like, in moving charge, electric field is different with the field generated by stationary charge.
...
- 254
0
votes
2
answers
357
views
How can Lorentz Force be defined for charges at rest as well as charges in motion?
We know that Electric field or electric force acts on charges at rest and magnetic force acts on charges in motion. But when we combine these two we get what we call as Lorentz force. So I want to ...
- 15
0
votes
1
answer
36
views
Magnetic field and frame of reference [closed]
A charged particle moves with a velocity near a wire carrying an electric current,and suppose I see the particle from a frame moving with same velocity in the same direction . I will see the charge at ...
- 99
1
vote
1
answer
93
views
Vectors in Force experienced by a current carrying wire? [closed]
My textbook lays out the following explanation of Force experienced by a current-carrying wire:
My question is where did the negative sign of the charge on electron go? How did Drift velocity go from ...
0
votes
0
answers
39
views
Determine magnetic force at a pole?
So my friend took a physics exam and one of the questions on it has me confused (It has been a long time since I have taken physics). The question was worded very badly (I had to translate from ...
- 101
1
vote
0
answers
61
views
Why does the term $-\frac{q}{c}\frac{d\vec{A}}{dt}$ play no part in the Lagrangian of a charged particle in an electromagnetic field? [duplicate]
A common derivation of the Lagrangian of a charged particle in an electromagnetic field starts with the Lorentz force that is rewritten in terms of the electromagnetic potentials $\Phi(\vec{x})$ and $\...
- 353
0
votes
2
answers
87
views
Does a magnetic field (moving relative to the charge) act on a stationary charge? [duplicate]
Does a magnetic field moving relative to a stationary charge act on it?
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5
votes
3
answers
851
views
Conceptual question about special relativity in electrodynamics
I‘m currently taking Physics II and I have a conceptual question about SR in edyn.
Suppose I have two electron beams with linear charge density $\lambda$ paralell two each other in a resting system $...
0
votes
1
answer
48
views
Force exerted by a charged ball on another one [closed]
Consider two charged balls in space with radii $R_A$ and $R_B$, and total charge $Q_A$ and $Q_B=\rho_B\space V_B$. They are separated by a distance $D = \|\overrightarrow{AB}\|\geq R_A + R_B$.
I was ...
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