For questions that utilize the concept of magnetic fields (commonly denoted by the letter B), or for questions whose answers likely involve magnetic fields. More specific than the [tag:magnetism], as questions about the phenomenon & theory of magnetism do not necessarily involve the discussion of ...

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Mutual inductance theoretically decreasing while EMF is increasing in 2 square coil system

I have a quick question regarding electricity and magnetism. I am measuring the induced emf in a square coil of wire with an inductance of 439uH (the other coil is also 439uH and is the same shape). I ...
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0answers
23 views

Aurora borealis forecasting, some technical details

I have an idea to make a software tool (with some really user friendly interface) for predicting auroras on any place on Earth. I do know some physics behind the phenomenon, but only basics, like it ...
2
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0answers
16 views

How to measure the permittivity of a gas sensor? [on hold]

I looking for a simple method to measure the permittivity of a gas sensor silicone.
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1answer
42 views

Transformers - Why more coils in second coil causes more voltage [duplicate]

I am learning about magnetic induction and transformers. I have coil1 which uses AC to create an oscillating magnetic field. I have ...
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0answers
14 views

Direction of CMB and magnetic fields?

Measurements show the CMB is warmer to the North. Could more photons coming from that direction of the sky, cause metals in the Earth to move in that particular direction? As the Earth orbits the ...
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0answers
17 views

How the magnet moves without pushing? [duplicate]

I video on Youtube represents that it can move through a coil without providing any external force and it seems that the force arises from the lines of forces generated in the coil. How can we ...
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1answer
29 views

Formula for Magnetic field due to current loop

I need expressions for $B$ field off the axis due to current loop. The ones I came across on the internet aren't very convincing. I verified them with Mathematica, and none seems to be correct. I'm ...
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1answer
24 views

Magnetar field energy density

According to Wikipedia a Magnetar... Earth has a geomagnetic field of 30–60 microteslas, and a neodymium-based, rare-earth magnet has a field of about 1 tesla, with a magnetic energy density ...
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3answers
36 views

Currents induced by rotation of a coil about magnetic field lines

If the coil on the left is rotated about the magnetic field lines, will there be an induced current? I know that the flux concerns only the component of the magnetic field perpendicular to the ...
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0answers
18 views

Applications of the study of Hamiltonians with constant magnetic fields

I am interested in understanding possible applications for the study of quantum systems with constant magnetic fields. For definiteness, consider the Landau Hamiltonian $$H_{0} = ...
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1answer
27 views

Does a rotating DC motor near a TV affects the signals coming in the TV?

In my TV cable the signals were quite noisy so i cut the wire and hanged both the wire parallel to each other. Then the signals became very clear and everything was going alright. Once I was ...
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1answer
15 views

What will happen to permanent magnet, if we keep same magnetic poles of two magent for long time?

What will happen to permanent magnet's magnetic field or magnetic ability, if we keep same magnetic poles of two permanent magnet for long time? Will any magnetic loss happens over the long period ...
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1answer
48 views

Magnetic force and frames of reference

I'm having a hard time trying to understand the next situation: Suppose that I have a magnet that creates a quite uniform magnetic filed $\vec B$. In the vicinity of this magnet there is a particle ...
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4answers
62 views

Does a magnetic field do work on a moving rod?

In a case such as this one, my textbook says that I might be tempted to think the magnetic force is doing work (against the moving rod). It then says this isnt the case because "charges move ...
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2answers
74 views

Is Magnetism and Electromagnetism the Same Thing?

I keep hearing everywhere that magnetism and electromagnetism are different but is seems to me that when a current is moving and it creates a "magnetic field", it is just electrons repulsing other ...
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1answer
22 views

Does the Magnetic Flux change (at a point) If the wire which causes it was cutted into a half?

If the electric charges move through a wire Does the generated Magnetic flux at any certain point chanage if this wire was cut into a half
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0answers
37 views

How to calculate the necessary magnetic induction to magnetize a certain ferromagnetic object and hold it

Well pretty much what I want to do is to build an electromagnetic coil with a nail inside of it for it to hold a steel ball. But I've come into some trouble, because I don't quite get how to calculate ...
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1answer
44 views

Why do Magnetic North and South Poles never exist by themselves? [duplicate]

As the title suggest, whilst I was reading I saw written that a 'Magnetic North or South Pole has never been found by itself'. And I was wondering why this was?
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1answer
37 views

Are magnetic orbits possible?

I have a small ball with lots of magnets embedded in it with all the north poles facing out and I have a big sphere with lots magnets embeded in it with all the south poles facing out. I set the ...
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0answers
26 views

Find magnetic field in a solenoid for different regions?

A steady current I flows along an infinitely long hollow cylindrical conductor of radius R. This cylinder is placed coaxially inside an infinite solenoid of radius 2R. The solenoid has n turns per ...
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2answers
37 views

Magnetic field at infinity

Does a magnetic field, generated by permanent magnets (for instance), vanishes "theoretically" (according to Maxwell's equations) at a very long (infinite) distance from the magnetizing devise? What ...
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1answer
26 views

Can two transformers used to make tesla coils?

Tesla coils seem to perform the same as a transformers: they use two coils and use magnetic field to transfer the energy. Doesn't using two transformers produce the same result? It doesn't seem to be ...
0
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0answers
25 views

What happens to a superconductor when a magnetic fields strength increases?

I'm curious about what happens when a HTS is locked in place above a magnet via the Meissner Effect and say another magnet is added. Would the superconductors height fluctuate? Or would the extra ...
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2answers
32 views

Magnetic Hysteresis

I'm a bit confused about when magnetic hysteresis occurs in ferromagnetic materials. Does it only occur with a rapidly changing external magnetic field or with a slowly changing field? Does the speed ...
6
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1answer
33 views

Spikes on ferrofluid?

What exactly are the spikes, or peaks and valleys, caused by in pictures such as these Wikipedia states that "From the point of view of magnetic energy, peaks and valleys are energetically ...
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1answer
21 views

energy in a current induced magnetic field

a mass of metal is near a current carrying wire, say a DC current. the metal feels a magnetic force of attraction and moves toward the wire overcoming some kinetic friction. the work done by the field ...
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1answer
40 views

Did the derivation of self inductance equation overcalculate winding number? [duplicate]

Let $L , I , \phi$ are self inductance , current and magnetic flux (created by each loop) of a solenoid with $n$ turns . $r$ is the radius of those loops . We have , $LI=n \phi = nAB $ [$A=\pi r^2$] ...
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0answers
38 views

Induced current created by a magnet falling in a copper tube?

One of the educational demos often shown in schools is to drop a high strength neodymium magnet down a length of copper tube. It takes a considerable time to exit the tube because as it falls it ...
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0answers
15 views

How can you relate magnetic dipole moment using bound current density?

This was on my midterm last week, the question ask us to use bound current density to compute magnetic dipole moment
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1answer
40 views

Closed and Open Electromagnetic Cores

I think I may understand this concept, but I haven't been able to verify with anyone that I'm going about this the right way. So when a wire is wrapped around a core that is a closed loop, like a ...
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0answers
29 views

Force and Torque being applied off-center due to magnetic forces [duplicate]

Say that I have two magnetic dipoles, one of which is rigidly attached to a freely movable inflexible body at some point that is not at the body's center of mass, while the other is fixed in space. ...
2
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1answer
35 views

About Right-Hand-Rule and Cross Projuct

In "Physics for Scientists and Engineers with Modern Physics - 8th Edition", p. 842, it gives the total magnetic force on the segment of current-carrying wire of length $L$ in a uniform magnetic ...
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0answers
19 views

How to find force acting on ferromagnetic material when it is placed in external magnetic field?

When we bring magnet towards ferromagnetic material ( like iron nails), then material gets attracted towards magnet. Since there is motion of material, there must be force acting on it. How to find ...
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1answer
31 views

Does zero free current entail zero $\vec H$?

There are two kinds of magnetic fields (different authors give them different names), $\vec B $ and $\vec H$ which are related by the equation $$ \vec B = \mu_o (\vec H + \vec M)$$ where $\vec M$ is ...
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3answers
113 views

Do mobile phones produce radiation harmful to humans? [closed]

What are the health effects of mobile phone radiation (if any)? Does using a mobile phone without an SIM card change the answer?
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1answer
37 views

Can I tear apart a pipe with magnetostriction? And how big field should I use?

As I know, with magnetostriction we can "stretch" its unit cell. The stronger is the field, the more it expands the cell. Using alternating current in coils that induce magnetic field we can stretch ...
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4answers
172 views

How any material can provide electrostatic and magnetic shielding

Several metallic objects like Iron, Copper etc can provide electrostatic shielding (one should remain inside the car during thunderstorm) and several superconductors like HTS (High Temperature ...
2
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2answers
48 views

Divergence of Magnetic Field in an Electromagnetic Wave

In many text books of physics (especially those coping with Electromagnetic Theory), we see that an electromagnetic wave (EMW) is drawn as an electric field varying with a sinusoidal form and exactly ...
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1answer
88 views

Why does Earth behave like Natural Bar Magnet?

What is the reason for the Earth to behave like a bar magnet and have poles (North and South poles)?
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0answers
48 views

Magnetic field derived from a scalar function

Question: Show that $\mathbf B = \hat r \times \nabla g(\mathbf r)$, where $g$ is an arbitrary scalar function, is a plausible magnetic field. What current density $\mathbf J $ can produce ...
2
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0answers
90 views

Field at the tip of a rotating cone. Is (THIS STEP) in my solution right? [closed]

** Edited: I'm going to CLARIFY where and what my question is. Problem: A hollow cone(like a party hat) has vertex angle $2\theta$, slant height $L$, and surface charge density $\sigma$. It spins ...
2
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1answer
70 views

How does the electric field pulse propagate during a change in the magnetic vector potential?

The electric field in terms of the electric scalar potential, and the magnetic vector potential is: $E = -\nabla\phi - \frac{\partial A}{\partial t}$, where $A$ is such that $B = \nabla \times A$. ...
3
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1answer
31 views

Why are the poles of a magnet reversed when a magnet is split into two?

This question may be odd, but today i noticed something when my little magnet split into two pieces. The poles reversed, so they could not get into "one piece" again (because the poles was ...
0
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1answer
34 views

Mimic Magnetic Repulsive Resistance through a spring

I have two identical magnets and I push them towards each other so that they are repelling. Is it possible to accurately mimic this repulsion effect (magnetic energy) just using a metal spring ...
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2answers
134 views

Magnetic force as a relativistic effect?

There is something I am confused about when it comes to the force between two parallel wires carrying current, specifically why when they carry current in the same direction the wires are always ...
0
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1answer
27 views

Magnetic interaction of wire and rectangular loop

In this video, Prof. Lewin shows an infinitely long wire and a rectangular loop at a distance $r_1$ from each other, each carrying a current. He then calculates the magnetic field resulting from the ...
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0answers
11 views

Strongest Magnet Material - Theoretical Limits?

In terms of field strength the current best (AFAIK) is NdFeB with small magnets capable of producing strengths on the order of one Tesla. Is there a theoretical upper limit on the field strength of ...
1
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1answer
86 views

Magnetic levitation frog example

I'm trying to figure out the strength of the magnetic field needed to levitate the frog, assuming it's spherical, has mass $5$kg and diameter $20$cm. I also assume $\vec{B}$ is uniform. Since it's ...
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1answer
30 views

What is the magnetic field on surface of a current carrying conductor?

Biot Savart's law says there should be none as the current element is along the displacement vector, hence as $\sin \theta = 0$, so, the magnetic field must be zero. But, as per Ampere's loop rule ...
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3answers
183 views

Why in a solenoid, do the magnetic field lines resemble that of a bar magnet?

Each loop in the solenoid will have its own magnetic field wrapped around it. In that case it won't resemble the magnetic lines formed by a bar magnet...; but we see that it is the same. Why is that?