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Questions tagged [electromagnetism]

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Is there an inward (radial) force acting on a magnet inside a magnet?

With a magnet inside another hollow magnet, for example an iron rod in a hollow cylinder, the iron bar placed inside the cylinder with poles attracted to opposite poles of cylinder (likes repel ...
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1answer
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In induction heaters why do metal pieces levitate in center of radial axis?

In induction heaters metal seems to levitate in center of radial axis, as well as longitudinal axis (see video). Is by any chance the reason for that like in this schematic, that magnetic field lines ...
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Iron bar inside solenoid, do magnetic field lines repel at sides?

Based on the closed loops rule, an iron bar inside a solenoid that has its poles aligned with the solenoid magnetic field, will have magnetic field lines around it along the sides that flow in ...
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1answer
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Are the magnetic field lines flowing from north to south _inside_ a bar magnet as well?

It seems based on the magnetic field of ring magnets like the magnetic field lines of a bar magnet actually runs from N to S also inside the magnet, yet schematic images tend to show the field lines ...
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Diametrically magnetised ring magnet, opposite poles on the inside?

I am wondering about the magnetic field on the inside of hollow magnets. As an example, will use a ring magnet. In a diametrically magnetised ring magnet, does the magnet have the same pole on the ...
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Are stator magnets in brushed DC motors radially magnetised?

In an electric motor like this one, are the stator magnets radially magnetised, as in, each of the two magnets has opposite poles on the inside and outside diameter?
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1answer
42 views

Can two-pole brushed DC motors have a ring magnet stator?

Is it possible to build a brushed DC motor with a ring magnet stator, instead of a stator with gaps as shown in the GIF below?
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1answer
14 views

What is the material requirement for Van der Graff generator sphere?

I would like to make a Van der Graff generator for my science fair project out of aluminized mylar. Do you think this might be feasable or do I need to use thick stainless steel ball? Is there some ...
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1answer
13 views

How to contain air ions inside a chamber without loosing their charge?

I would like to create an experiment where I would hold ionized air molecules. Most likely negative O2-1 ions. I am looking for the most appropriate enclosure so that the ions do lose as little of ...
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1answer
71 views

Can a Foucault's current brake be used on the rails themselves to brake trains?

Your typical Foucault's current brakes operate on a disk, which is placed in an electromagnetic field in order to transform kinetic energy into heat without friction. The problem is that the disk ...
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1answer
49 views

Is there a motor design where a rotor gradually moves into a stater?

I was wondering if there is a motor/generator design where the rotor moves gradually in and out of the stator along the axis of rotation, or the stator over the rotor. If so, I'd like some resource(s)...
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1answer
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Magnetic treatment of hard water to prevent scale and corrosion? How does this work?

I ran across this company at their booth at a Tradeshow (2018). They claim to have a chemical free (and as far as I can tell - a power free) treatment method for hard water to minimize scale and ...
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2answers
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Can you use an electromagnet to break the connection of a permanent magnet?

At first, I had a particular goal, but I'm starting to doubt feasibility which has led me here. Original Goal: Create a small (3in²) electromagnet with 100% duty cycle capable of holding at least ...
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1answer
40 views

Can magnetic stripes be read wirelessly with lasers or other technologies?

I know that magnetic stripes used in credit cards and audio tapes are typically read by a magnetic reader head. But is it theoretically possible for the stripe to be read by a laser in a similar ...
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1answer
27 views

Can a electromagnet find a tube underground?

I was seeing how an electromagnet could attract a car when it's destroyed, and I was wondering, because I have to find the water tubes in my house (20/40 cm depeer), if I can put a wire inside the ...
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Restricted Rotation using electromagnets

I was wondering if I could restrict the rotation of a part over another in one direction alone using an electromagnet but allowing me to have a continuous rotation if forced (maybe by using some ...
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Is it possible to protect electronics on a cubesat from 100-1000g of acceleration

I am currently researching the feasibility of setting up a coilgun that launches Cubesats for a paper.
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1answer
42 views

Difference between permanent magnet and electromagnet exciter generator in principles wise?

I searched about this, but couldn't find any helpful explanations. All it says is that magnetic field is generated by either permanent magnets or electromagnets. In both cases, how does the exciter ...
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1answer
24 views

DC relay relation with resistance

Is there any method or formula that can be used to find the operating voltage of a coil using the resistance of the coil? If so, is it also applicable to AC coils or any other technique?
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What are the strengths and limitations of the antenna design of the Montjuïc Communications Tower?

The Montjuïc antenna is an interesting design for an antenna. I presume the design is principally an antenna, but perhaps it is not? If the ring + mast is an antenna, how does the ring work to ...
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0answers
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Method to simulate a dipole antenna in salt water?

I am looking to simulate the radiation pattern of a 2.7Ghz half-wavelength dipole antenna immersed in salt water. I've been using Altair FEKO software to try and accomplish this. I've tried two ...
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1answer
61 views

Cheapest way to produce 200-1000 pieces of 0.2 mm copper plates

I want to build a strong electro magnet. I came to the conclusion that the smartest arrangement would be something like hundreds of thin sheets of 0.2 mm copper with PTFE isolation. This reduces ...
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2answers
47 views

Compensating for a magnet in a device with a magnetometer

I'm working on a device that relies on data from a magnetometer. Unfortunately, the device also needs to have a fairly powerful magnet on it. Given that the design is fairly flexible, and within ...
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Transistor and diode on induction cookware

Will a 1 kW induction cook top damage a transistor which is kept on its surface? If yes, what is the mechanism? Is it electromagnetic induction?
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1answer
28 views

Induced voltage in an arc of wire

We know that time varying magnetic field produces voltage in a coil. But what if the wire forms a semicircle or an arc instead of a complete loop, will such magnetic field produce voltage between the ...
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0answers
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Can AC carrying coil be used to destroy electronics?

An air core coil carrying AC current of frequency f will produce an oscillating magnetic field of max amplitude say b inside it. If an electronic devices or component say transistor is placed inside ...
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0answers
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Does the Hyperloop One suspension require constant current through copper windings?

As a follow-up to How does the pressurized suspension of the Hyperloop not affect the tube pressure?, I believe (though I can't find where I read it now) that the Virgin Hyperloop One implementation ...
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1answer
37 views

A radar that is not an OTH detection distance

Let's say that we have a radar that is not an OTH on a boat, and it is placed 30 meters above the ground. Is there a way for it to detect an offshore platform 152 kilometers away from it, since the ...
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0answers
43 views

Dynamic magnetic field Vs electronics [closed]

It seems dynamic magnetic field may damages electronics components like diode, transistor etc, probably via electromagnetic induction. How much strength and what frequency magnetic field is ...
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0answers
54 views

Differences between shell type and core type transformers

What is the advantage of a shell type transformer over core type and which one has smaller flux leakage?
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0answers
39 views

Coefficient of Friction, Passive Magnetic Bearing

While comparing magnetic bearings to others ceramic bearings, a rough first point maybe to compare would be the two different bearings' coefficients of friction. This is just a thumbnail comparison ...
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1answer
45 views

Generating practical power without an iron core, but with high RPM

Here's what I'm proposing - a small turbine directly coupled to a permanent magnet that's spinning at, say, 150k RPM. The magnet is enclosed one or several wire loops parallel to the axis of rotation. ...
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0answers
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Can an antenna damage an iPhone?

I am currently attending a radio technology course. We continuously work on radio sets that are sometimes used as manpacks by the Army. In order to learn how to operate them we work in close proximity ...
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1answer
64 views

Quantifying Static Electricity Hazard with High Explosives

In the making of firework explosives, the explosive mixtures are handled with great care to avoid static electricity induced detonation of the explosives. Is it a good idea that they store the ...
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1answer
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Should we use ELF or ULF for very deep metal detection and which specific frequency?

We are trying to design a metal mineral deposit detection system using low frequency radio waves. I am not sure on the physics of why the ultra low frequency electromagnetic radiation can penetrate ...
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How would an electromagnet function within an MRI? [closed]

For the purpose of this situation. Lets say there are 4 small electromagnets within a MRI. All of them activate at the same time. The entire setup is comprised up of non ferrous metals. The metals ...
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1answer
32 views

Steel surface welding with high-frequency current

High-frequency currents induce skin-effect resistance that is used on some applications to weld metals. Assume you have two steel rectangles of dimension $h_0, w, l$ and $h_1, w, l$ placed together ...
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2answers
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Is there any material that blocks a static magnetic field?

Is there any material that blocks a static magnetic field? So that if I put it between a magnet and a piece of metal, they won't interact with each other?
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1answer
64 views

Using electromagnetic induction to fire a neuron

In order to make a neuron fire via an external electrode, the electrode must input some electrons in the extracellular space(just outside of the neuron). Imagine a straight conducting wire touching a ...
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1answer
272 views

Moving carbon nanotube in a magnetic field

When a metal wire moves across a magnetic field, voltage is induced across it, which is equal to $BLV$, where $B$ is strength of magnetic field, $L$ is the length of wire and $V$ is its velocity. Will ...
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1answer
104 views

Effect of arc welding on nearby electronic devices [closed]

Will an electronic device,say a smartphone or wifi router, get damaged if there is an arc welding going on in the vicinity? I am not talking about damage from direct contact with the fire/spark, but ...
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1answer
72 views

How much does human tissue attenuate radio frequency signal of a given frequency?

Attenuation of radio frequency (rf) signals in a medium depends upon medium characteristics and frequency of the signal. How much does human tissue attenuate rf signal of a given frequency?
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2answers
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Can a wireless signal of sufficiently high energy damage a wireless transceiver?

A wi-fi router works at 2.4GHz. Can a wireless signal of 2.4 GHz or any other frequency, of sufficiently high energy, damage the device?
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How do brass models work (radar)?

A common practice in naval research is to construct brass models of ships to study the reflectivity of a vessel. This can (supposedly) be used to understand the way it reacts to radar and the way ...
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2answers
165 views

How to split mercury with a magnetic force?

Do you think, one could split a mercury drop into two drops with the magnetic force? Mercury is a liquid metal, hence if I put a current through it, it will become a electromagnet (a wire with a ...
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1answer
51 views

Defining camera as a passive radar

Is it possible to define any camera without "flash" (sensible to any band of radio wave) as a passive radar? If so, where could I find references to that? I've been looking all over the place and ...
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0answers
111 views

How to simulate Ground Penetrating Radar system?

We have a project which requires Ground Penetrating Radar(GPR). We got a student license of NI AWR software and Ansys HFSS (high frequency structural simulator). Are those the correct software for ...
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0answers
35 views

using a coil for an electrochemical reaction

I wish to calculate the amount of energy required for electrolysis through induction, instead of electrodes. If there is a crucible metal core with solution inside and the coil wrapped around it. Can ...
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1answer
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How is it possible electromagnets keep a heavy maglev train levitating without forcing anything metallic to be flinged away?

I always wondered how it is possible to have electromagnets so strong that they keep a heavy maglev-train levitating without forcing anything metallic to be flinged away or to be pressed against the ...
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0answers
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How powerful should a magnet be to be able to pick the cans from the floor?

I bought a 4 W Electromagnet to collect aluminium cans laying on the floor. A can weighs around 0.015 kg. I read aluminium is only paramagnetic. And playing manually with the current magnet, ...