The magnetic-fields tag has no wiki summary.
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Why the magnetic flux is not zero?
According to Maxwell's equations the magnetic flux over a closed surface must be zero, why in this case does not happen?
Thanks for your help
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Is it possable to create a magnitive field genarator, over the magnitive field [closed]
I had this dream that I was working on this machine. It looked like a donut shaped magnet and it was over the poles of the magnetic field. There was no electric motors to get it started , but the out ...
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2answers
81 views
Can a current carrying loop or wire produces no magnetic field?
A current carrying wire produces magnetic field around it. We can find the direction by Fleming's Right hand rule. We know change in electric filed produces magnetic field and change on magnetic field ...
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59 views
Do all known planets and moons have magnetic field?
In this Wikipedia article it is stated, that magnetic field of Earth is caused by currents in her core. The same origin is for Jupiter magnetic field.
For Moon (article) there is a magnetic field, ...
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76 views
Easy question about magnetism?
I have to build a simple electric motor by attaching a magnet to a battery, extending the terminals of the battery (with stiff wires so they could act as supports), and placing a coil of wire on top ...
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Row of pivoted magnets and energy scale
This question is about a system involving a horizontal row of length L of equally spaced pivotable magnets, each with a pole at either end. These magnets will often be referred to as units.
So each ...
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1answer
51 views
What causes the collapse of a Magnetic Field?
It's theorized that Mars once had a magnetic field which collapsed at some point.
There's also lots of speculation that a similar process will eventually happen to Earth. More recently has been the ...
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1answer
66 views
Difference between electromagnetic radiation (EMR) and Electromagnetic Field?
I'm a freshly graduated electrical engineer. One course that I really struggled with was Field Theory, because it was a lovely assortment of vector calculus and things that were explained to me well ...
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1answer
30 views
A simple electromotor?
I have to build a simple electromotor in the following way: I attach a permanent magnet to a battery, connect some metal supports to the terminals of the battery, and place a coil of wire on the ...
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1answer
68 views
Purcell and the Magnetic Field
When showing that the magnetic field derived from the curl being proportional to current and the divergence being zero is unique, Purcell says that at some sufficiently remote enclosing boundary the ...
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31 views
Magnetic Field versus Line Charge
Isn't a magnetic field basically an electric field originating from a line charge, but as seen in a boosted frame? I mean, that's where the relativistic explanation comes from right?
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4answers
59 views
North and south of magnetic field
The current I is flowing upward in the wire in this figure. The direction of the magnetic filed due to the current can be determined by the right hand rule.
Can we determine the north and the south ...
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1answer
58 views
Magnetic Field and the Speed of Light
Is it just a historical choice that both magnetic field and the Lorentz force equation include the speed of light?
I figure that whoever wrote up the equations (in cgs!) could have put both factors ...
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1answer
82 views
Liquid benzene magnetic susceptibility
In a solid state physics problem, I'm asked to make a rough estimate of the contribution to the diamagnetic susceptibility of the outer electron of each carbon atom. The wavefunction of these ...
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Cause a change in the magnetic field detectable by a smartphone Magnetometer
I hope someone can shed some light or point me in the right direction.
I have a smartphone that has a Magnetometer built into it. I'm exploring some ideas
of how I might be able to use it. I want to ...
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36 views
Magnetic field of a Ferromagnetic cylinder [closed]
I have been stuck on this problem for hours and have no idea how to go about this problem.
You have an infinitely long cylinder made of linear ferromagnetic material of relative permeability Km, ...
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35 views
Magnetic field due to a rectangular wire [closed]
I have a infinitely long rectangular wire with width = 6cm, height = 0.1cm. A point P is 27 cm away from the center of the wire. I wanna know the magnitude of the magnetic field at this point. The ...
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1answer
54 views
What is the Earth's magnetic field in space?
I have looked around a bit, but haven't found a simple answer. At an altitude between 100-1000 km,
Is the magnetic field B still around $\sim 10^{-5}\ T$? Is there a simple equation that would provide ...
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2answers
106 views
Cancel out Earth's Magnetic field
Is there any tools except helmholtz coil to cancel out earth's magnetic field to calibrate magnetometers in practice.
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Difference between electrostatic and magnetic field [closed]
In this, F (the force set by the field) is perpendicular to the speed of the particle. In which case does F change the absolute value of V? Why or why not?
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How to design a AC/DC generator and motor? [closed]
Through electrodynamics mechanics learning, it is possible to design a simple and elegant design for the following four machines:
1. AC generator
2. AC motor
3. DC generator
4. DC motor
I have some ...
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1answer
65 views
Movement of the particle in a magnetic field
This is the numerical question.
A particle having a mass of 0.05 mg carries a charge of $5\times10^{-6}C$. The particle is given an initial horizontal velocity of 5000 m/s, what is the magnitude ...
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2answers
166 views
Effects of a very large magnetic field on the human body
Ever since reading about the NHMFL I have always wondered about this and asked several people without getting a good satisfactory answer. My question is, considering the simplest case let's say a ...
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1answer
62 views
A good theoretical approximation for a magnetically damped pendulum
In a laboratory course we had to perform an experiment with a pendulum (just an iron weight on a wire) and play around for some time with its wire's length and so on.
This was quite boring and we ...
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80 views
Equation of motion of charged particle under effect of magnetic field
A charged particle with specific charge q/m diverges from the origin [to the first quadrant] by angle X with x axis and with velocity v. To bring the particle back to the x axis, a magnetic field B is ...
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1answer
54 views
If I have a rectangular loop moving through a magnetic field, which way will it go?
If I have a rectangular loop moving through a magnetic field, which way will it go?
A uniform magnetic field (say it's pointing into the page)
A square/rectangular loop of wire moving into the field ...
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39 views
Magnetic field at a point [closed]
Find the magnetic field near a straight current carrying conductor of Length $L$ and current $I$, at point located along the perpendicular bisector of the wire a distance $r$ from the wire. Show all ...
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Is it possible to measure outside magnetic field from inside a car?
I know that I can detect a vehicle by using magnetic field. I can see obviously difference in signal when a vehicle pass. But I don't see that when measuring in a car.
Is it possible to measure ...
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1answer
50 views
B-field and Magnetic forces, speed of a particle
Let's say I have a particle moving perpendicular to a uniform magnetic field of magnitude $x \ T$, and it moves in circle with a fixed radius. How do I find the speed of this electron? Initially I ...
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1answer
118 views
Do magnets lose their magnetism/force when they attract/repel each other?
So yea, if two magnets attract/repel multiple times(A LOT) will they lose their magnetism? If they don't break during the whole process?
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1answer
114 views
Eddy current losses in electric steel by harmonics of a magnetic field
I am working on an model of a permanent magnet synchronous machine. Right now I am stuck with calculating the eddy current losses caused by the harmonics of the stator magnetic field in the electrical ...
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Is a Magnetostatic Approximation Appropriate for a Coilgun Application?
I have little experience with magnetodynamics. Any help would be greatly appreciated.
I have an overdamped RLC circuit as the firing mechanism of a coilgun. A small cylinder of iron (a nail or ...
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4answers
300 views
How do permanent magnets manage to focus field on one side?
The actuator of a hard drive head consists of two very strong neodymium magnets, with an electromagnetic coil between them. If you take that apart, the magnets attract each other very strongly. ...
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1answer
55 views
Possible to generate an electromagnetic field from moving an object through a magnetic field?
Is it possible to generate an electromagnetic field from a stationary rare earth magnet with a hole in it by passing an object through the hole?
By definition, a Lorentz Force is the force on a ...
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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 ...
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1answer
405 views
Magnetic Fields created by Current-Carrying Wires
The drawing shows two perpendicular, long, straight wires, both of which lie in the plane of the paper. The current in each of the wires is I = 5.6 A. What is the force and torque acting on each wire ...
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Calculating attracting magnets?
I have two identical bar magnets...
Each bar magnet can lift an object with 10lb of force.
When they attract each other, I believe that each magnet applies a force of 10lb to attract the other.
That ...
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2answers
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Should I use Coulombs law when magnets attract/repel?
When magnets attract to each other or repel.
Should I use Coulombs law? If not, why not?
Some would say that I shouldn't because: "Coulomb's law deals with static charges and force due to them. ...
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Effect of strength of magnetic field on the height of a levitating superconductor?
Quantum levitation, flux pinning -- basically, when a superconductor floats above a permanent magnet, is really fascinating. But does the strength of the magnetic field influence the superconductor's ...
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Induction cooker + superconductive pot
What will happen if I put a super-conductive object on an induction cooker, and turn the cooker on?
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1answer
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Why doe we not get a shock on induction cooker?
In induction cooking, eddy currents in cook-pot cause heat to be produced. But why do we not get a shock?
Also, why is it that current is converted to heat while it has a good conductor(say, steel) ...
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origin of magnetic field in a permanent magnet [closed]
I have a simple question. I hope I don't get a stupid answer. Where does the magnetic field of a permanent magnet comes from AND why is it permanent (are we dealing with perpetual motion)?
This is ...
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1answer
113 views
Is my electric power cord creating magnetic field when coiled?
Simple question. But I was wondering, does my mac power cord create a magnetic field when its all coiled?
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1answer
83 views
Force of electromagnet on piece of iron
I can find equations to give the force of an electromagnet on a piece of iron when the iron touches the electromagnet.
But what about when the iron is some distance from the electromagnet? ...
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52 views
Would a magnetic rod through Mars shield it from solar wind?
Would a magnetic rod going all the way through Mars shield it from solar wind?
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1answer
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Magnetic field line length
If I had a magnetic bar in space that was 2cm wide and 2cm high and was one Earth diameter long and had the same magnetic strength as the Earth, would the distribution of field lines be the same ...
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1answer
180 views
Basic magnet through a copper coil experiment - What if poles were rotated 90 degress
I was wondering what voltage or current, if any, would be produced if the basic magnet through a copper coil experiment had the poles rotated 90 degrees so north and south faced the top/bottom of the ...
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2answers
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Charged quantum particle in a magnetic field - choosing a different gauge leads to different wavefunctions
Consider a charged quantum particle confined to the $xy$ plane, subject to a magnetic field $\mathbf{B}=B\hat{z}$.
The Hamiltonian is:
$$ H = \frac{1}{2m} \left( \mathbf{p} - \frac{e ...
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What name would you give to the method of approximating an arbitrary magnet with many smaller dipoles?
Let's say I had an arbitrarily shaped permanent magnet, with total magnetic moment $M_{0}$. Ways to calculate the magnetic field of this magnet include an analytic solution (if one exists), as well ...
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Some questions regarding magnetism [closed]
We have a spring scale with a inductor hanging to it. The inductor has 100 loops, has a length of 2cm and a mass of 300g (see picture below). A homogeneous external magnetic field is perpendicular to ...
