Tagged Questions
1
vote
0answers
43 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
106 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
28 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 ...
0
votes
0answers
47 views
electrostatic repulsion [closed]
Consider a homogeneous ring of radius $R$ made of a thin wire of cross section $A$ with $R^2≫A$. A charge $Q_1=10\mu C$, uniformly distributed over the ring, broke it apart due to electrostatic ...
2
votes
1answer
34 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 ...
0
votes
2answers
52 views
Electrical force as a replacement for Gravitational force [closed]
Suppose the force between the Earth and Moon were electrical instead of gravitational, with the Earth having a positive charge and the Moon having a negative one. If the magnitude of each charge ...
4
votes
2answers
82 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
20 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
144 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
121 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
54 views
Reason behind cohesive and adhesive force
What is the real cause behind the cohesive and adhesive forces?
0
votes
0answers
220 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 ...
0
votes
0answers
32 views
How can I determine the magnetic nature of three sealed boxes? [closed]
For my Physics class my partner and I have to do a lab assignment where we have to determine the magnetic nature of contents of three sealed boxes. My question is how can I write this information down ...
1
vote
1answer
223 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
128 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
197 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
466 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
128 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
76 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
218 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
210 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
159 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
160 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 ...
7
votes
4answers
805 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
144 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
3answers
148 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
372 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, ...
4
votes
1answer
296 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 ...
3
votes
3answers
1k 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
630 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 ...
2
votes
1answer
470 views
How does one calculate the force applied on an object by a magnetic field?
I've tried very hard to find an answer to this question, and every path leads me to an abstract discussion of fundamental forces. Therefore, I will propose two very specific scenarios and see if they ...
7
votes
3answers
2k views
What is the cause of the normal force? [duplicate]
I've been wondering, what causes the normal force to exist?
In class the teacher never actually explains it, he just says "It has to be there because something has to counter gravity." While I ...
1
vote
3answers
349 views
What was meant by the 'ponderomotive force' as understood by Minkowski?
Skimming through Minkowski's famous 1907 paper, he uses the term ponderomotive force.
What does he mean by this?
1
vote
2answers
220 views
Pollen Particle Attracted to TV due to Which Force?
A pollen particle has no charge so I cannot understand how the Lorentz force $\bar{F} = q \bar{E} + q(\bar{v} \times \bar{B} )$ could explain the event. I speculated that it is because of the electric ...
3
votes
1answer
120 views
3 current loops with non-conservation of momentum, when one specifically considers SIGNs
Thought experiment I.
Consider two loops of wire, 2 small dipoles B and C , with a common axis z (facing each other) and (say) 30 cm apart B to C. At the speed of light, information (including a ...
3
votes
4answers
276 views
existence of other forces obeying inv square law
Is there any restriction in what we know of physics to the existence of other type of forces that obey the inverse square law in 3 dimensions.
I mean other than electromagnetic and gravitational.
...
0
votes
1answer
330 views
How is a magnetic field translated into physical force?
Related to this question
Where do magnets get the energy to repel?
If I have a magnet repelling another, eg one in my hand, the other being pushed along the desk, how do the each of the magnet's ...
8
votes
9answers
6k views
What's the core difference between the electric and magnetic forces?
I require only a simple answer. One sentence is enough... (It's for high school physics)
7
votes
3answers
497 views
How can we make an order-of-magnitude estimate of the strength of Earth's magnetic field?
The source of Earth's magnetic field is a dynamo driven by convection current in the molten core. Using some basic physics principles (Maxwell's equations, fluid mechanics equations), properties of ...
