Questions tagged [electromagnetism]
The kind of magic without which all of this wouldn't be possible. This tag should be used for questions about the **physics** of the fields that charged particles create and how these fields interact. It should not be used for all questions involving electromagnetism; that would be everything on the site.
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How much magnetic force is required? [closed]
How much force in Newtons is required to attract 1 gram of stainless steel (AISI 304 type 20% Cr) with a cross-sectional area of 0.2 mm from an electromagnet if the separation distance is 0 and if ...
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Slowest Possible Speed of Electron [closed]
What is the slowest velocity/speed (in km/s) at which we can fire a single individual electron, especially in vacuum, considering our current technological level?
Note - I am asking for speed which ...
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What would be the effects of a -1000 nanotesla geomagnetic storm be on modern electronics?
After reading the Wikipedia article on geomagnetic storms, I'm curious about what the effects of a -1000-nanotesla-minimum geomagnetic storm would be on modern military and consumer electronics, as ...
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Difference between a flared and not flared rectangular waveguide antenna
Someone can explain to me the difference in terms of performance between a flared rectangular waveguide antenna (precisely a pyramidal horn) and a not flared rectangular waveguide antenna?
In horn ...
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What is happening at the gate of a JFET to cause an electric field?
I am reading "Practical Electronics for Inventers" 4th edition and came across this circuit.
As I understand, for a JFET, current will flow from drain to source for a n-channel (opposite ...
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Is there any way to wind this 4 pole motor to behave as 2 or 8 poles properly?
I got an induction motor in a junkyard, a WEG motor made for an Electrolux washing machine.
It is a single-phase 1/2 hp 4 pole motor. It runs in 127 V and has a 40 uf capacitor feeding the auxiliary ...
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Why are capacitors more dangerous than batteries?
It seems decent size capacitors can electrocute you when it's charged. Somewhere I read capacitors don't have internal resistance therefore, current is NOT limited unlike the batteries with internal ...
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Nominal current for my design using AA battery
I am designing an electromagnet and I'm deciding on the wire gauge to wrap my coil in. It's going to be powered by 6V batteries (using 4 AA 1.5V batteries).
The problem is that I used a current of 0....
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What happens if two wires intersect [closed]
I'm pretty sure electric currents don't interact like this but if I were to make a NOT gate, with a wire, where one point is where current comes from and the other point be an output and the wire is ...
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Finding the ideal parameters for a homemade electromagnet
I am making an electromagnet and I was watching some videos on designing one. I just have some misunderstanding about power calculations of electromagnets and I have some questions about it.
Q1)
1.1) ...
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Electromagnet design and powering it up? (Fault prevention of DC supply for a small coiled Electromagnet)
I want to create an array of multiple electromagnet which I will be controlling using a microcontroller.
I will have around 100 such magnets lined in a squared grid 10x10. Only three or five at a time ...
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How do steel laminations reduce eddy current losses in a transformer?
All online materials I have read so far state that laminations reduce eddy currents but how is this so? I mean why would currents be smaller this way than having a big block of unlaminated iron core ...
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Phase angle difference between the induced EMF in the rotor and the rotating magnetic field in three phase induction motor
I have been studying the three phase induction motor and in the process I could not exactly understand the EMF generation in the rotor.
From figure(2) below, it is understood that the maximum EMF is ...
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Shielding bottom of PCB in THT design
I'm designing a PCB where I could use one layer as massive groundplane and shield. Do I have to make some form of shield for THT part pins, or are they small enough to not pickup a lot of ...
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How can I calculate the current induced in the copper coil that is wrapped around a single phase of an 11kV, 2616A distribution line?
Aim: To develop an alert system for power outages in the distribution line, informing electricians of their occurrence.
Working Principal:
Fuse Monitoring: The Arduino measures the status of the power ...
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Does the law of reciprocity hold true for the phase response of an antenna?
I know that an antennas spectral transfer function should be the same in both transmit and receive due to the law of reciprocity, however does this law hold true for the phase response (AKA phase ...
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Problem acquiring B-H curve
I'm trying to acquire the BH curve of a toroidal current transformer in saturation, having the primary and secondary current.
The formulas I am using are:
B = (1/NsS) Integral(Vs(t)dt)
H = (Ip*Np)/l
$...
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Why does my in-wheel BLDC motor have sinusoidal back emf (line to line) when rotated by external system?
I have an in-wheel BLDC motor with 46 poles (permanent magnet) on the rotor and 51 slots in the stator. When I used an external machine to rotate my in-wheel BLDC motor, then measuring across two ...
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Signal diode to protect high speed data lines
I don't understand this. Could someone explain this to me? I have a hard time imagining how it works. Why would the signal line be protected by connecting the diodes this way?
If you get an ESD event ...
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How to connect a 12V electromagnet to 220V power adaptor
I'm not very familiar with electronics, but I want to create a basic automatic pet feeder for my outdoor dog house. My idea is simple: a wooden box with a floor that drops at a set time, controlled by ...
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Reverse electrowetting on dieletric using air bubble displacement for electricity generation
I read this research paper and it uses bubbles to change the electrolyte and electrode interface, thus causing a change in capacitance as the bubble forms and exits the electrolyte.
For reference: ...
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Yagi antenna with 16 dBi gain, is it bottle necked by the power input?
I want to expand my PC's WiFi range, but the NIC delivers only 5 W. When I connect the antenna, not much more range is achieved. Is the antenna not the right one, or is the output of 5 W not enough? ...
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Electromagnetic Energy Harvester
It was suggested I make a new post since the topic was growing in complexity.
I am looking into constructing an inductor to utilize electromagnetic induction near a high voltage transmission line. If ...
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Direction of current in a wire connecting two conducting loops placed concentrically in a time varying magnetic field which is into the plane of paper
Figure shown plane figure made of a conductor located in a magnetic field along the inward normal to the plane of the figure. The magnetic field starts increasing. What will be the direction of ...
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Expression vectorial to magnetic field \$\vec{H}\$ in infinite semi-plane conductor
I have some difficult to figure out the second expression about the contribution of magnetic field as you see below:
Problem:
A wire conductor, infinite long (Z axis), conduct a current constant equal ...
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Magnetic interaction between resolver & motor windings?
Scenario: Synchronous electric motor whose rotor position is measured by a resolver.
Won't the magnetic field created by the motor stator & rotor, link with the primary & secondary windings ...
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How can I read a high frequency PWM falling edge with Arduino interrupts?
My project is about a Magnetic Levitator. I control the electromagnet with a high frequency PWM signal which I use on the MOSFET gate to give to it enough current.
The thing is that I use a linear ...
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Building an MRI safe video camera (e.g. webcam)
I would like to use a small camera inside an MRI. The eye-tracking cameras that are commercially available are both too expensive and also not suitable for my purposes.
How would one go about making a ...
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Does the bremsstrahlung radiation size depends on the size of the accelerator?
According to this, HERMES III, a 16 terawatt pulsed power accelerator at Sandia National Labs, which fired electron beams with peak energy at 22 MeV and 730 ka current that later converted into ...
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Electromagnetic Pendulum Pulse Driver - Having Trouble Getting Circuit Running
Now I'm not super well versed in circuits though I've dabbled a bit in some circuit building in the past. I'm working on an electromagnetic driven pendulum for a clock I'm building. The Schematic I'm ...
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The electric and magnetic components of far field EMR and shielding thereof
This is a newbie question. I'm pretty sure of the answer, but I would like confirmation. I found this thread in this forum that came close to what I was looking for, but I think my question is ...
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Energies carried by electric and magnetic fields in plane waves
This is a newbie question. I'm trying to understand what I think must be a very basic concept with an obvious answer, but I want to be sure.
Do plane wave electric and magnetic fields of equal ...
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Energies of the fields in a plane wave, attenuated and unattenuated
This is a combination of two of my previous questions (question 1 and question 2) which are related.
I'm trying to learn both how energy is carried in the electric and magnetic components of a plane ...
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Why does magnet wire need to be insulated?
What is it about having multiple coils that enables the magnetic field? Why can't I just have one big wire or threaded wire on a motor? Sorry, it's kind of a baby question but I couldn't find the ...
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Converting air compressor to gas but leaving ac motor on
I have a compressor with the crankshaft being the the front part of the shaft of an A/C motor's armature.. The rear of the AC motor's armature has enough protruding shaft to put a pulley on it and ...
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Undesired oscillation in an electromagnet control system causes the levitating object to fall
I have been struggling with a college project, being so close but yet so far from making it work succesfully.
I have designed an electromagnet control system that has to control the position of an ...
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Are E and B fields in phase in electromagnetic radiation?
I recently wrote this answer, in which I said:
Radio waves are electromagnetic radiation. Electromagnetic radiation contains of two components, one electrical and one magnetic. These components ...
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How is the holding force of this electromagnet so large?
I am designing a system that uses the magnetic force to fix an object in its place. I plan to connect an I-core to my object and fix it to a fixed C-core by letting a magnetic flux flow through both ...
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Placing a reed switch behind a metal plate
If put a reed switch behind a metal plate in plastic casing and have the bar magnet sweep across the plate in parallel, would the reed switch activate? I would try it myself but the reed switches that ...
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Troubleshooting thermionic emission
I am attempting to make an electron beam device work. The setup is very basic - a wehnelt in a vacuum chamber connected to an AC filament heater source and a DC high voltage source as pictured below. ...
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Derivation of electric field intensity for Line charge
These snapshot is taken from Principle of Electromagnetics by Matthew N.O. Sadiku.
In this derivation I don't understand the highlighted step. In previous step we are defining a position vector R ...
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Increase magnetic power from a coil
I'm building a project which basically consists of the electronics inside a lucky cat: a coil that generates a magnetic field to make a permanent magnet move, which is attached to a swing. Check this ...
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Example of computation of S matrix
Let's consider the slide 1 of this material.
I have understood the computation of S11, but not that of S21.
I do not understand:
- why there is the circuit with V and two impedances Z0 and there is ...
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H Field in a Rectangular Loop Carrying Constant Current
Question: A rectangular loop carrying 10A current placed on \$z=0\$ plane as shown in figure. Find \$\vec H\$ at i)\$(2,2,0)\$, ii)\$(4,2,0)\$, iii)\$(4,8,0)\$, iv)\$(0,0,2)\$.
I just tried to draw ...
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Question about RF waves and it's effect on electronic devices
Could a let's say 50 W RF wave (2.40 GHz and 5 GHz) cause disturbance in nearby devices like Laptops? (Data corruption, random opening of applications and programs, random commands, etc.)
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How to optimise wire gauge selection for electromagnetic applications?
Disclaimer: Hobbyist "maker" with limited experience and no relevant education. Please considerate and answer in detail. Feel free to skip to "Question".
Context
I have an ...
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How to Limit Current Using L293D?
I’m designing a circuit to control 4 electromagnetic coils and subsequent orientation of a sphere (pic attached below). I’m new to EE but thanks to this forum I’ve learned what and how to utilize PWM ...
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Reflection coefficient of a transmission line with discontinuity
I have a question, let's say that we want to calculate the Reflection Coefficient that we see by watching from left to right of the red-line this circuit:
Let's say that:
Za= Equivalent Impedence of ...
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Electromagnet doesn’t have power [closed]
I have so problem with an electro magnet, I mean it seems a little weak to me. What could I do to improve it’s power? Battery: 3.7V 8800mAh
Also, I had the wires in small parts so that’s the reason ...
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Energy regenerative snubber for flyback converter
I am trying out the regenerative snubber design in https://core.ac.uk/download/pdf/215381319.pdf page 13. The circuit configuration is shown in the figure below:
I am unable to derive the following ...
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