Questions tagged [electromagnetism]

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31 views

Implications of different LCD tecnology

https://www.techspot.com/article/2322-display-tech-compared/ I appreciate that IPS panels use a parallel alignment of crystals and they rotate, while VA panels use a vertical alignment and they tilt. ...
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2answers
51 views

Angle of incidence in concave mirrors

What happens when you change the angle of incidence(normal to the mirror)? How does the angle of reflection change? Is it invariant?
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3answers
101 views

Magnetising a needle with static electricity using silk cloth

A nautical navigation textbook on my table says that we can magnetise a non-magnetised needle by rubbing it with a silk cloth. I decided to cross check on the internet, and found some experts calling ...
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13 views

Stepdown transformer core magnetizing

I am looking to get better understanding of transformers as I would like to connect a Variac to the primary of a step down transformer to create a linear variable dual rail test power supply for audio ...
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30 views

Clarification on number of poles(magnetic) and induced/output voltage

I get that turning a loop of wire across a pair of magnetic poles induces a magnetic field. But I don't really understand how frequency plays a role in this. I've read a bit and saw that frequency is ...
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30 views

Insulated Wire - Radio Signal

I am looking for a relativity inexpensive wire for consumers whose insulating jacket will prevent radio signals from leaking. We are installing a pet radio fence at home. If you are unfamiliar with ...
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58 views

Why isn't power going into my apparatus

I am using a LightingWill Waterproof IP67 LED Power Supply: https://www.amazon.ca/gp/product/B07T1WRQ4H/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 to power a magnetohydrodynamic drive with a ...
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1answer
55 views

How this synchronous motor works and how to modify them?

I have the following synchronous motor ripped out from an old range hood in my kitchen. I used new electrician tape to cover up the coils that should form the electromagnet--the old cover is too oily....
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39 views

magnetic levitated tower - magnetic fields and tensile strengths of materials [closed]

I was considering a system made from a stack of electromagnetically levitated platforms and wondering how you would go about comparing its tensile (and or compressive) strength to that of a solid ...
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30 views

What is the most efficient way to convert shaking/vibration to electrivity?

What is the most efficient way to get electricity from shaking? I am thinking about something like shown in the picture below (the magnet is going inside the coil), but maybe there is a better design ...
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43 views

How to send true digital data in discrete values?

To my understanding signals in any form sent through empty space is in the form of electromagnetic waves. This implies that it is never discrete two values but it can be modulated. Looking at this ...
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1answer
23 views

Linear solenoid mount

I have a linear solenoid with a tapped M3 hole at the end of the plunger, like this: I need to connect this plunger to a lever, so I want to add a mount which has a connection something like this: ...
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1answer
32 views

Use magnetic levitation to lift a carousel capable of turning 9000lbs [closed]

Allow me to describe my current situation. I have a 18 ft (5.486 m) carousel that is assembled using steel beams that are bent into two circles, an outer and an inner. And there are steel spokes ...
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1answer
30 views

Can you shape a magnet and how would it effect its field [closed]

Long story short im playing with mental designs of an electric motor and I'm not sure on some things regarding magmets/magnrtic materials and my designs are in flux do to these variables. I'm ...
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28 views

Calculate the temperature stability of wavelength demultiplexer

Hi ive been given this question: A wavelength demultiplexer (DMUX) used in a DWDM communication system has a channel spacing of 100 GHz. The operating pass band of each channel is 50 GHz. The ...
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1answer
66 views

Can waste heat in specific environments be collected into photons and converted to electricity?

This question is a repeat of another post on the physics board Here and here show the possibility to combine photons of lower energy to higher energy. Thinking of an application, it could be used to ...
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1answer
55 views

Ripple tank simulation for simulating light waves? [closed]

Can anyone help shedding some light on how ripple tanks are programmed? example I'm looking to simulate light waves, to perform theoretical calculations, as opposed to for just visual effect. The ones ...
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54 views

Is there an analogy between mechanical vibrations and electromagnetic waves

Recent questions about analogies between mechanical and electrical systems and about electromagnetic waves from a conductor made me wonder whether there is an analogy between the mechanical vibrations ...
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1answer
25 views

Is there a way to quantify the amount of radiofrequency interference?

Is there a way to quantify the amount of radiofrequency interference? Do any units exist that quantifies how much radiofrequency interference is there?
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3answers
83 views

What Goes Into Making a Variable Field Magnetic Motor?

(I feel it is necessary to mention that I am not an electrical or mechanical engineer; I just like to build fun things.) I've already got a good explanation of the concepts involved in a variable ...
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66 views

DC and AC Simulation on Ansys Maxwell for calculating the core and winding losses in an Inductor

I want to simulate the core and the winding losses in an inductor using Ansys Maxwell when imprinted with a triangular pulse(positive RMS Current). I am doing a DC simulation to get the inductance ...
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2answers
30 views

Is VLF-EM scanning for fractures a valid way to find groundwater for a well?

I need to choose where to drill an agricultural well. I am trying to get as much water as possible (at least 100 gpm). I am considering hiring a guy who claims to be able to find water using a device ...
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49 views

Solenoid with 3mm stroke and ~1ms response time possible?

I need to extend and retract a needle as fast as possible with dwell time while retracted, while one option I really like would be to use Scotch Yoke with dwell. However that would mean the stroke and ...
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16 views

Determining the magnetic reluctance of a straight flux path

Currently I run into an issue understanding the following. The bottom part of this magnetic circuit is made from steel which has a finite relative permeability. However, the flux paths is made out of ...
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1answer
77 views

Can be used a lab on a chip device as a nuclear fusion device? [closed]

This is what a lab on a chip is https://en.wikipedia.org/wiki/Lab-on-a-chip I ask if could be used as a nuclear fusion device , that could rise the number of nuclear fusion per atom, knowing that ...
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1answer
131 views

Why are the synchronous reluctance motors not self-starting?

I have been studying synchronous reluctance motor since a month. I am curious to know why is this motor not self starting? If used with an inverter, this motor can be made self-starting. Or by adding ...
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1answer
30 views

Utilizing solenoids in electric motors

I have seen videos of solenoid engines but there were claims that they were inefficient unlike DC motors. I was wondering what would be the most efficient use of a solenoid in an electric motor. ...
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1answer
96 views

Building oscillating magnetic field circuit

I wanted to create an oscillating magnetic field using an electromagnet which is rated for 12V continuous duty. I was thinking that I need an arduino to control the electromagnetic circuit by using a ...
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1answer
49 views

Why don't car manufacturer's use a combination of disc brakes and electeomagnetic brakes to reduce braking distances?

It many be due to costs or that the brake discs would have to be made out of aluminium/copper for the electromagnetic braking to be effective or there may not be a significant reduction in braking ...
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33 views

BLDC Motor underwater ; weird behaviour

I recently was riding my e-bike (with a bldc hub motor) and decided to cool the motor (it -the stator- was approx 100-150 celcius I think) in the river. The controller is on the top of the bike and ...
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1answer
46 views

Protect equipment against electromagnetic radiation [closed]

They say that in the near future high cosmic radiation is possible. In addition, the Earth’s magnetic field is likely to weaken. I want to create something like a camera that would protect against ...
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2answers
531 views

Why does this magnetic charger cause short circuit when it sticks to the metal leg of my table?

Recently, I have bought this product. It is basically a USB cable, with a magnetic end, and a tiny attachment that goes into the mobile device. I plugged it into my laptop cooling stand (which has ...
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233 views

Please explain this flatbed microwave design

Here is a Galantz flatbed microwave The waveguide is smaller than a wavelength. 1)Usually apertures of less than a wavelength are considered to block EM wave but not here, why ? 2)The width of the ...
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143 views

ElectroMagnetic Pulling Force fdropoff with distance

I am looking make a quick and dirty test ring using an off the shelf electromagnet. My force needs are small, less than a pound but I need to do so in a non contact manner. I know these magnets are ...
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50 views

DC motor Magnetic axis of armature winding vs EMF

When considering the cross section of a DC motor we have: I notice that the Magnetic axis of the armature winding is aligned with direction of the EMF that will cause the rotation. Is there a ...
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1answer
65 views

How do old wind turbine towers pickup magnetism overtime?

I was conducting some robotics tests on a old wind turbine today, and noticed strong magnetic fields around the steel tower. This magnetic field does not exist on other modern wind turbines at the ...
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2answers
344 views

How do maglev trains turn given that they seem to have more than two bogies per car?

All of the images of maglev trains that I've seen seem to have a continuous drive mechanism along the entire length of each car: I assume this must be articulated some how, or the train wouldn't be ...
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1answer
59 views

What emits more radiation, cell network or wifi?

I've researched in the Internet but can't find any conclusive answer. When will your phone emit more radiation, downloading 1 Mb of data from a cell network (3G, 4G) or downloading the same amount of ...
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39 views

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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2answers
139 views

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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3answers
237 views

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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1answer
234 views

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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1answer
133 views

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
142 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
63 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
21 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
155 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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2answers
143 views

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

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 moves over the rotor. If so, I'd like some ...
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1answer
65 views

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
146 views

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 ...