# Tagged Questions

2answers
37 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 ...
0answers
69 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 ...
0answers
15 views

### 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 ...
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 ...
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 ...
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 ...
0answers
23 views

### 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 ...
0answers
34 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, ...
2answers
105 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.
2answers
82 views

### 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?
1answer
74 views

### 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 ...
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 ...
2answers
163 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 ...
1answer
61 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 ...
0answers
79 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 ...
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 ...
0answers
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 ...
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 ...
1answer
114 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?
1answer
112 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 ...
0answers
20 views

### 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 ...
4answers
293 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. ...
1answer
54 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 ...
4answers
103 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 ...
1answer
397 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 ...
0answers
49 views

### 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 ...
2answers
129 views

### 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. ...
3answers
228 views

### 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 ...
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?
1answer
81 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? ...
1answer
176 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 ...
0answers
41 views

### 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 ...
0answers
106 views

### Why are magnetic lines of force invisible?

We can very well feel the magnetic field around a magnet, but we can't see it. Why is that so? Also, can we cut a portion of the field and use it?
0answers
21 views

### Rosenberg-Coleman effect

I know only that it states some variations of the Sun's magnetic fields. What is the Rosenberg-Coleman effect specifically?
0answers
72 views

### Is there an equation for the magnetic field of a conductor attached to a magnet?

Let's say I have a hollow conductive rod, 10mm diameter (O.D.), and I place a magnet of known strength 50mm up the shaft. What is the microTesla (mT) or Gauss (G) of the magnetic field (or flux ...
0answers
60 views

### Would an aluminum cup placed around the back and sides of a disc magnet increase the field strength at the front?

I have read that certain materials, specifically ones with distinct magnetic properties, can influence the way magnetic field behaves around a magnet. If you were to place a disc magnet inside an ...
1answer
107 views

### Linear dependence of magnetic potential on current density

I'm a mathematician learning physics to provide some background for my mathematical work (especially pde's!). I have been reading through Jackson's Classical Electrodynamics (3rd edition), and I was ...
1answer
56 views

### Is it possible to determine astronomically/astrophysically whether other planets have ever encountered polarity reversal?

We know of geomagnetic flip in Earth's history by studying geologic data. Given other planets in the system also possess a magnetic field leads to the assumption that such polarity reversal may not be ...
1answer
288 views

### Physical meaning of magnetic length

What is the physical meaning of magnetic length $\ell_B=\frac{\hbar c}{e B}$ in 2D electron system under magnetic field? When $\ell_B \longrightarrow a$, where $a$ is the lattice constant, does that ...
1answer
131 views

### Point where resulting magnetic field is equal to 0

I am trying to solve the following task Given 3 infinitely long current carrying wires, as shown on image ($I_1=I_2$ , $I_3=2I_1$) and $r=5 cm$ calculate the point between them (in the same plane; ...
1answer
88 views

### How does a magnet work?

I'm having trouble understanding how a magnet (not the field that is generated as a result but the material itself) work. The particles are aligned in a specific direction to give rise to force but I ...
0answers
68 views

### Changing the charging properties of an inductive charging coil

I am attempting to modify an existing inductive charging coil (Palm Touchstone) so that it outputs the correct magnetic flux for a different wireless charging standard (Qi). I am doing this as an ...
2answers
118 views

### Force on a bar magnet

A bar magnet is freely falling vertically inside a conducting ring placed in horizontal plane. Will it fall with an acceleration equal to g, less than g or greater than g?
1answer
237 views

### Mutual Inductance and the Dot Convention

Can anyone please explain me, the dot convention in coil systems (Mutual and self inductance) with some related images to understand..?
2answers
2k views

### Why does electricity flowing through a copper coil generate a magnetic field?

Can some one please explain to me why electricity flowing though a copper coil generates a magnetic field or where I could possibly find that information? Are there other materials that produce a ...
2answers
403 views

### Mechanism by which electric and magnetic fields interrelate

I read that force due to electric field on some particle in one reference frame can exhibit itself as force due to magnetic field in some other reference frame and that electric and magnetic fields ...
1answer
109 views

### Separation of solids from liquids using magnetic waves

Using magnetic forces, I want to separate solids from liquids in a solution as a centrifuge would do. Is there a way to hit a volume of liquid and get it to separate liquids and solids with heavy ...
3answers
664 views

### How to make a small tokamak?

$\require{mhchem}$I made a fusor once, like the easy science project: deuterium-deuterium ones, but they're really inefficient. I was wondering if it would be possible to make a small tokamak; not one ...
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