# Questions tagged [magnetic-fields]

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 [magnetism] tag, as questions about the phenomenon & theory of magnetism do not necessarily involve the discussion of fields.

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### Angular Acceleration of a wire in a magnetic field

My physics book presented me with this question: A copper wire with density $D=8960 \;\text{kg}\,\text{m}^{-3}$ is molded in the shape of a circular spire with a radius of $r=0.50\;\text{m}$. The ...
1answer
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### Hysteresis curve in ferromagnetic materials

Suppose I have a ferromagnetic material that is inside a chamber where you can somehow control the magnetic field. The image represents its magnetization in function of its applied magnetic field. a) ...
0answers
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### Is the magnetic field at the centroid of a closed loop connected at two different points to a battery always zero?

Given a closed 2-dimensional conducting loop, the terminals of a battery are connected at any two points on the loop (but not the same point). As an example, consider a circle of radius $R$; the two ...
0answers
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### Line current above conducting plane

Question: If you have a line current in the z-axis with current I and a conducting plate parallel to it at distance d. The magnetic field is zero inside this plate, as is for every perfect conductor, ...
3answers
32 views

### Why is there no conduction current $i_C$ through a surface between capacitor plates?

The image is from Young and Freedman's University Physics with Modern Physics, Chapter 29 (Electromagnetic Induction). The image shows a parallel plate capacitor being charged where the current ...
0answers
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### Will close-loop increase magnet force?

If I have two magnets, and I use an iron to make it a close-loop magnet with a gap. Will the close-loop magnet force at gap stronger than the force of two separate magnets?
0answers
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### Torque of a three phase synchronous motor

I'm searching a way to express the torque of a three phase synchronous motor with permanent magnet in function of the current. I took as the magnetic field of the stator this expression : \$\vec B(M,t) ...
0answers
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### Can we interchange the quantities involved in Fleming's left hand rule?

Fleming's left hand rule states that If we stretch the thumb and first two fingers of left hand in mutually perpendicular directions such that forefinger points along B (Magnetic field vector) and ...