1
vote
3answers
72 views

Protons and Electrons Occupying the Same Space

When it comes to atoms electrons can't fall into the nucleus, which besides the off hand uncertainty explanation, I'm not sure which force prevents them from falling into the nucleus. I thought I ...
0
votes
2answers
31 views

How to express magnetic field vector in terms of force on current

I am preparing for an exam and one of the questions I have come across asks: Define the electric field $\mathbf{E}$ and the magnetic flux density $\mathbf{B}$, in terms of the force on charges and ...
1
vote
0answers
61 views

Currents and magnetic fields produce forces that affect things they're not touching?

I was doing this past paper and am a little confused by question 5) part c)ii) I correctly calculated that the force acting on the rod due to the magnetic field is 0.016N but I can't see how ...
-1
votes
1answer
50 views

How do magnetic objects exhibit attraction/repulsion across empty space?

Magnets will attract or repel over a distance before physically touching each other. What makes this effect possible? My best guess is that the forces generated by the angular momentum of the ...
7
votes
2answers
143 views

Why don't black holes form from forces other than gravity?

Gravity is the weakest of the fundamental forces, so what is so special about gravity that it can form an inescapably strong field while a force like the EM force cannot? It seems to me that if there ...
2
votes
1answer
149 views

Does a current-carrying wire running through the centre of a solenoid experience force?

Imagine looking at a solenoid from above. Current passing is through it in a clockwise direction. The direction of the field lines therefore is towards the bottom of the solenoid. Now pass a straight ...
2
votes
1answer
102 views

Contradicting forces on a circular loop under current in magnetic field?

I have the following general conceptual concern. Think of a thin conducting loop of radius $R$ placed in the $x$-$y$-plane at $z=0$. There is a homogeneous current density $\vec{j}$ running through ...
1
vote
2answers
109 views

How far could one fire a charged particle in space?

I've wondered how far would be able to send a concentrated beam of electrons in space. The reason is would we be able to launch a magnetic ring with an electron absorbing material on one side and just ...
0
votes
1answer
45 views

Does the Lorentz force applied to a current carring wire by a magnetic field act in the negative or positive direction of the right hand rule?

If I say that I am calculating the Lorentz force $F$ applied to a wire carrying a current $i$ at a point $P$ in a magnetic field $B$, would the actual force be opposite of that given by the right hand ...
1
vote
1answer
57 views

Cause of radiation resistance

I was reading Radiation Damping and light scattering from Feynman's lectures on physics. The following excerpts are from chapter 32, Vol I What is this radiation resistance due to? Let us take a ...
3
votes
2answers
362 views

Do two magnets stacked on top of each other repel/attract stronger than just one magnet?

In designing a switch, I made it such that it "springs" back via two neodymium magnets (one in button repelling one in switch). I've found the magnets are too weak and don't spring back. I've resorted ...
3
votes
2answers
113 views

Classical electrodynamics formulated in terms of forces

The Newton's law of universal gravitation is described in terms of a force, which is produced by an action at a distance. It also can be described using the concept of a field, and that would be an ...
0
votes
0answers
68 views

Calculating repulsion due to eddy currents?

I have a conductive particle moving at a known speed through changing magnetic field (Permanent magnets attached to a rotating drum alternating north/south). These particles will have induced eddy ...
0
votes
2answers
139 views

Does the magnitude of an electrical field change with frequency?

I am trying to model the frequency response of a force (dielectrophoresis) that is based on gradient of an electric field. One of the components is the CM factor which has a frequency component, but ...
0
votes
1answer
32 views

Want to achieve maximum magnetic force & find out the max point [closed]

Hi Sir/ Madam Want to achieve maximum magnetic force & find out the max point for this setting, want to know is the strongest magnetic force must in the 'dot' area ( middle poin of setting ) ...
2
votes
1answer
988 views

Force between two bar magnets

I need to know how to calculate force between two bar magnets. I searched and found an answer on Wikipedia, but I don't really trust Wikipedia, a lot of crazy stuff is posted there. So I searched ...
2
votes
2answers
690 views

Do electric and magnetic lines of force physically exist?

As per my imagination any thing can't impose force on the other by not giving even a touch(i,e action at a distance). So I thought there must be some physical existence of lines of force. Although ...
4
votes
2answers
403 views

Why is the voltage drop across an ideal wire zero?

I'm having trouble conceptualizing why the voltage drop between two points of an ideal wire (i.e. no resistance) is $0~V$. Using Ohm's Law, the equation is such: $$ V = IR \\ V = I(0~\Omega) \\ V = ...
0
votes
1answer
121 views

what is in the electrostatic field that makes the word done independent of path taken?

I am trying to understand how is it possible for electric force to behave like this (path independence)? I am repeatedly failing to get an intuitive meaning behind its (electric field) nature of ...
2
votes
0answers
74 views

Consistency of equation with special relativity?

The following is the equation which, I want to know, if it is valid in relativistic domain. Consider two equal charges moving in same direction with velocity $v$ and charge $q$ at a separation of ...
1
vote
1answer
209 views

Dielectric slab counter-intuitive formula?

For the calculation of force on one of the two equal(in magnitude, opposite in sign) point charges separated by $r$ with a dielectric slab of dielectric constant $K$ and width $d$ in between, the ...
2
votes
1answer
271 views

Two electron beams exert different forces on each other depending on frame of reference?

I am sure there is a simple explanation for my confusion, but I am a little puzzled: We are dealing with two parallel electron cannons that each produces a straight beam of electrons. They are placed ...
0
votes
0answers
35 views

Viscous force in a conductor

I was told that in a conductor there is a dissipative force and if Ohm's Law is valid for a component, the component has to be dissipative. I'm trying to prove it, but I have some problems. I know ...
1
vote
0answers
727 views

Calculation of magnetic force magnitude from a parmenant magnet

I was wondering how strong a magnet should be in order to be able to horizontally attract 0.2 Kg of pure iron at a distance of 0.3 M. Since I know nothing about magnets, I started looking for ...
3
votes
1answer
137 views

Is there any potential associated with magnetism

Can anybody please tell me if magnetism is a conservative force or if there is a field associated with it? How to reason? One thing I know is that the work done by a magnetic force is $0$.
2
votes
1answer
93 views

Magnetic Force on a Loop and number of turns

Suppose we have a rectangular current-carrying loop with current $i$, then we know that the magnetic force on each side can be found as: $$F=iL\times B$$ Where $L$ is the vector in the direction of ...
2
votes
1answer
66 views

Falling through the ground [duplicate]

I do not know much about physics but I know that according to Newtons third law of motion when we walk we are pushing the ground down but the ground is pushing us up. What force is making the ground ...
7
votes
2answers
218 views

Forces as One-Forms and Magnetism

Well, some time ago I've asked here if we should consider representing forces by one-forms. Indeed the idea as, we work with a manifold $M$ and we represent a force by some one-form $F \in ...
0
votes
0answers
22 views

Some basic questions about electric field & nucleus [duplicate]

I am not good in physics.You can say I am beginner in this field. I have some basic questions. I ju st want to know that [1] If there is repulsive force between same charges proton-proton then why ...
4
votes
2answers
446 views

Relativistic Lorentz force law

If we consider the the relativistic Lorentz force law: $$\frac{d}{dt} (m\gamma \vec{u})=e(\vec{E}+\vec{u} \times \vec{B})$$ How can we deduce: $$\frac{d}{dt} (m\gamma c^2)=e \vec{E} \cdot \vec{u}$$ ...
2
votes
4answers
201 views

Why in $F = iLB$, $L$ is a vector but $i$ is not?

I learned $F = iLB$ recently. However, I don't understand why $L$ is marked as a vector but $i$ is not. For a normal rod, how should I define the direction of length vector $L$? And if I reverse the ...
2
votes
1answer
193 views

Reason behind cohesive and adhesive force

What is the real cause behind the cohesive and adhesive forces?
0
votes
0answers
327 views

How to calculate the force between two different magnets?

I'm doing an experiment and I need to calculate the force between two magnets with different stats, different sizes and flux density. I learned physics in high school so I know all the terms. In my ...
1
vote
1answer
437 views

Gravity force strength in 1D, 2D, 3D and higher spatial dimensions

Let's say that we want to measure the gravity force in 1D, 2D, 3D and higher spatial dimensions. Will we get the same force strength in the first 3 dimensions and then it will go up? How about if ...
1
vote
3answers
204 views

So do I use this Lorentz's law or which law do I use?

I have difficulty understanding exercise 24 in this document: Two parallel wires I and II that are near each other carry currents i and 3i both in the same direction. Compare the forces that the ...
0
votes
1answer
411 views

What kind of force is it when you push a door shut? [duplicate]

Possible Duplicate: How can I stand on the ground? EM or/and Pauli? It probably seems like a silly question to a physicist, but I'm from a pure maths background and don't know an awful lot ...
3
votes
4answers
1k views

Are the field lines the same as the trajectories of a particle with initial velocity zero

Is it true that the field lines of an electric field are identical to the trajectories of a charged particle with initial velocity zero? If so, how can one prove it? The claim is from a german ...
1
vote
1answer
220 views

Calculating the direction of the force acting on a source of magnetic field

I do not know how to calculate the direction, or unit vector of the force that appear between two magnetic field sources. For example, let's assume I mean a current-carrying-wire by 'source of ...
2
votes
0answers
94 views

The force exerted by a ~10 Tesla magnet on a C13 isotope?

How much force would a ~10 Tesla magnet exert on a weakly magnetic C13 isotope? If I made a molecule of diamond with $N$ C13 atoms, how large would $N$ need to be for me to pull on it with something ...
2
votes
2answers
364 views

Demonstrate magnets adhere to conservation of energy pursuant to the laws of thermodynamics

I am looking for a way to demonstrate that magnets adhere to the laws of thermodynamics, in particular the requirement that energy in a closed system be conserved. To adhere to the requirement that ...
0
votes
1answer
613 views

How positively charged protons remain glued to each other while they should repel each other out of nucleus? [duplicate]

Possible Duplicate: Protons' repulsion within a nucleus How positively charged protons remain glued to each other while they should repel each other out of nucleus?
2
votes
2answers
209 views

Interaction speed between electric charges and magnetic materials

Einstein said that the speed of a matter in universe cannot exceed the speed of light. Is it correct for electric force transmission speed from one electric charge to other one? What is ...
3
votes
2answers
262 views

Does constraint for speed of Electric and magnetic fields violates Conservation of momentum or Newton's third law?

I'm just a beginner so bear with me. Consider two frames at rest wrt to each other separated by distance enough for light to take a minute or so. At a given instant we create two large dipoles by some ...
8
votes
5answers
1k views

Is the EmDrive, or “Relativity Drive” possible?

In 2006, New Scientist magazine published an article titled Relativity drive: The end of wings and wheels1 [1] about the EmDrive [Wikipedia] which stirred up a fair degree of controversy and some ...
1
vote
0answers
193 views

Modeling the trajectory of a particle in an Electric field [closed]

[This problem has been resolved, sorry for posting in the wrong forum!] (I was trying to model the trajectory of a particle in an electric field.)
1
vote
4answers
214 views

Magnetic force and work

If the magnetic force does no work on a particle with electric charge, then: How can you influence the motion of the particle? Is there perhaps another example of the work force but do not have a ...
6
votes
1answer
712 views

Degeneracy Pressure, What is it?

There has been numerous question, some violent even in physics@SE regarding PEP and EM forces. But what baffles me is what is degeneracy pressure? I know there are 4 fundamental forces- EM, gravity, ...
5
votes
1answer
390 views

Lorentz force law in Newtonian relativity

I know that in special relativity Electric and Magnetic fields mix together in different reference frames, but my question is about classical mechanics. It seems weird to me is that the Lorentz Force ...
9
votes
4answers
2k views

Can the Lorentz force expression be derived from Maxwell's equations?

The electromagnetic force on a charge $e$ is $$F=e(E+v\times B),$$ the Lorentz force. But, is this a separate assumption added to the full Maxwell's equations? (the result of some empirical ...
2
votes
4answers
1k views

Work done by the Magnetic Force

The magnetic part of the Lorentz force acts perpendicular to the charge's velocity, and consequently does zero work on it. Can we extrapolate this statement to say that such a nature of the force ...