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Identifying and designing coils for generating parallel magnetic fields with smooth gradients

What is this coil called (see image) (blue line is field, blue circle is clockwise oriented coil, red circle is counter-clockwise oriented coil), and are there any tools that help design it? ...
user1402154's user avatar
2 votes
3 answers
131 views

Measuring magnetic fields in the 1-10 Hz range

I apologize in advance but I am a chemist just venturing into the world of electrical, so you may need to explain to me like a 5 year old. I have a chemistry project that involves the use of AC ...
LeviB's user avatar
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1 vote
1 answer
134 views

Why is resistance (inversely) proportional to area instead of circumference?

TL;DR From the Veritasium-vs-ElectroBOOM debate about the 1 m / c question, it seems to me that most properties about conductors depend only on surface charges. So shouldn't quantities like resistance ...
eccentricOrange's user avatar
4 votes
3 answers
1k views

Why is it not standard practice to integrate the output of an antenna?

This is a follow up question from my question answered here: Why does a loop antenna not measure the differential magnetic field? Essentially I just found out today that we are actually measuring the ...
Christian's user avatar
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1 vote
2 answers
131 views

How does electricity flow if circuit is not complete? [closed]

https://youtu.be/oI_X2cMHNe0 What is he saying at 13:20? How can bulb glow if the circuit is not complete?
Shubham Singh's user avatar
2 votes
3 answers
435 views

Does infinite magnetic permeability (e.g. for an ideal transformer) violate conservation of energy?

The ideal transformer is supposed to have infinite magnetic permeability. Creating infinite magnetic field lines from a finite applied field sounds like... a violation of conservation of energy or ...
artist_and_not_EE_by_training's user avatar
2 votes
3 answers
1k views

Building a solid state regulator for a vintage 6 V dynamo

There was a great discussion back a few months ago on building a regulator for a dynamo. I have a similar challenge except the vintage motorcycle I'm restoring is a racing machine - neither lights not ...
clairefromperth's user avatar
0 votes
3 answers
220 views

Contradiction in Gauss's law?

I have a question that my teacher was explaining but the question seemed to contradict the real world. I know it has got to be my understanding that is flawed but I cannot seem to get it. So here goes:...
An aspiring Scientist's user avatar
0 votes
1 answer
94 views

Trouble with body effect physics

I’m struggling to understand why a negative voltage applied to the bulk contact of an n-type MOSFET increases the threshold voltage. I read other similar questions and I get that the negative voltage ...
ale_zec's user avatar
  • 15
0 votes
1 answer
600 views

BLDC Hall Sensor Angle Offset

I'm running a BLDC motor and I'm working on my own Software. I want to run the BLDC Motor with field oriented control, that's why I need a precise electrical angle. I'm using three hall sensors in the ...
xone's user avatar
  • 1
0 votes
2 answers
157 views

Is this circuit measuring the electrical field?

I have found the following circuit on the web (https://electroclinica.org/2018/03/23/fabricacion-de-un-sencillo-medidor-de-campo-de-rf-diy/) which claims to be an "RF field" detector/meter/...
78dtat78da's user avatar
2 votes
1 answer
541 views

Calculate the active and reactive power of the connected load after field increase in synchronous generator

A 3-phase synchronous generator connected in Y configuration has the following given parameters \$V_L=38kV, R_a=0.3\Omega,X_s=2\Omega, S=360MVA, cos{\phi}=0.83\$ Where the parameters correspond to ...
Ανδρέας Παπαευριπιδης's user avatar
0 votes
0 answers
179 views

Helmholtz coil - I don't understand the circuitry

I work in a testing laboratory. We recently introduced in our repertoire a testing method using Helmholtz coils to generate a magnetic field. In order to have a magnetic field I need to have current ...
i33SoDA's user avatar
  • 91
-1 votes
2 answers
268 views

Why is the magnetic field not blocked by the copper wires in a current transformer?

When I want to protect an electronic board from a magnetic field generated by a transformer, I put a circle of vias (as a jail grid) connected to GND planes to stop the magnetic field. How does a ...
zian's user avatar
  • 37
0 votes
1 answer
106 views

Help understand the role of an inductor and its value (educated guess)

This circuit is a part of a field strength meter circuit in an old magazine, the value of inductor J1 is unknown (due to a print error in the magazine.) The circuit works like this: With S1 open and ...
gino's user avatar
  • 489
0 votes
2 answers
598 views

How many newtons are there in one coulomb of charge?

Or, I should have said, how many newtons of force does one coulomb of charge exert? At a distance, presumably, of one meter? Since N/C is supposedly equivalent to V/m? P.S. What are the values for a ...
Kurt Hikes's user avatar
10 votes
4 answers
1k views

Construction for a homogeneous field using permanent magnets

Please let me describe what I am trying to achieve and I will pose my question in the end. I am trying to design a small chamber which can have a uniform magnetic field inside. I want to see if a ...
tony31's user avatar
  • 103
7 votes
1 answer
2k views

Sewing machine motor repair

I'm a sewing machine mechanic, trying to increase my electric motor knowledge. I have a Bernina 830 sewing motor where the carbon brushes ran down and the wire damaged the commutator and ran a groove ...
Billie's user avatar
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0 votes
1 answer
617 views

How to detect a magnetic field from a distance?

I want to detect a magnetic field, like those of small neodymium magnets, from at least 6 inches away (the further the better, I'd like at least a foot but I won't ask for too much). I'd like to do ...
Slade W. Cooper's user avatar
2 votes
2 answers
2k views

A very basic question about PLC field input switches

Below shows two simple ladder logic examples written for a PLC: As far as I understand, the -| |- and -|/|- above are the symbols we write for the PLC not the actual input switches. But we also need ...
ty_1917's user avatar
  • 1,006
2 votes
1 answer
641 views

Does this sensor measure electrical or magnetic fields (with oscilloscope)

I want to measure electrical and magnetic fields of the frequency 50Hz to 1MHz with my oscilloscope. For electrical fields I learned that any bunch of metal will work. For magnetic field derivation ...
Hansebenger's user avatar
0 votes
2 answers
251 views

Magnetic field of a coil composed of stacked coils

Basically my question is that if you have a coil with N turns with its ends connected to a source of current (I), and you have another coil which is N number of single coils stacked on each other with ...
Tom's user avatar
  • 507
1 vote
1 answer
1k views

Interface conditions and surface current density

let's consider the interface condition for magnetic field strength: 1) I do not have a clear idea of what js represents. If I have understood it correctly, it is a linear density ([A/m]) of a surface ...
Kinka-Byo's user avatar
  • 3,510
0 votes
1 answer
149 views

Does a pcb as patch antenna isolate itself?

I'm currently working on a prototype patch antenna for UHF. Since I'm out of copper at the moment, I used empty PCB's as base material (don't mind the PCB in between, it's only a spacer): So now my ...
Essigwurst's user avatar
1 vote
1 answer
335 views

Magnetic Monopoles and Magnetic Current Densities

I see that in electronic engineering the Maxwell equations are written with also some terms which represent the magnetic charge and the magnetic current densities. I was told they are inserted only to ...
Kinka-Byo's user avatar
  • 3,510
0 votes
0 answers
257 views

Alternator field winding VS equivalent inductor

I have a question which I know is going to be more opinion biased than factual. I know this isn't the purpose of the forum, but I would really appreciate some extra opinions so I'm going to ask it ...
David777's user avatar
  • 1,492
1 vote
0 answers
190 views

Should I daisy chain start connect or wire separately?

This is related to field wiring schemes and interference. Sometimes tens of transducers are needed to be coupled to a single-ended data acquisition board's analog input channels where the transducers ...
user1245's user avatar
  • 4,215
4 votes
1 answer
1k views

Detrimental impact of magnetic field on PCB and battery?

We are developing a small consumer electronics product consisting of a small 4-layer PCB along with a few PDM microphones and BLE chip/ an antenna, as well as a LiPo battery. We are locating a small ...
T. Chains's user avatar
-1 votes
3 answers
6k views

What is the SI unit of magnetic force?

As derived from F = qvB sinθ, what is the unit of magnetic force, and why? Edit: I mistakenly asked about magnetic field before. -- I'm asking the magnetic force.
Vyun's user avatar
  • 27
1 vote
1 answer
53 views

What determines the direction and cause of electric field exerted on test charges?

-I understand when there is an on-going electric field, if it is produced by a positive charge, the direction of electric field is away from it etc. And, if we get a +ve test charge, it repels it, and ...
Vyun's user avatar
  • 27
0 votes
1 answer
705 views

Enhancement type MOSFET - channel formation

In an enhancement type MOSFET (an n channel one assumed here), when a positive gate to source voltage is applied, the holes of the substrate near the gate move deeper into the substrate away from the ...
Curiosity's user avatar
  • 171
0 votes
1 answer
1k views

Question on MOSFET - small signal model

In the small signal model of a MOSFET, the current from the drain to the source (for an n channel MOSFET) is a function of the gate to source voltage only. But, if a positive voltage was not applied ...
Curiosity's user avatar
  • 171
0 votes
1 answer
99 views

E fields and M fields in Near Field

I am reading a textbook that mentions that small loops with high dI/dt on a PCB tend to produce predominantly magnetic waves and stubs with high dV/dt tend to produce predominantly electric waves in ...
EasyOhm's user avatar
  • 4,649
0 votes
0 answers
92 views

What is the direction of electric field inside a battery?

Outside the battery, in the conductor it is in the direction of conventional current. But what about inside? Somehow linked: For p-n junction, at the depletion region which side is at higher ...
Sahil's user avatar
  • 145
2 votes
3 answers
1k views

Solenoid's field intensity calculation dependency on width/diameter of coil?

Textbook formula for field intensity in solenoid coil is H = (N * I) / l H magnetic field intensity in ampere-turns NI ampere-turns l is length between the coil ...
VladBlanshey's user avatar
0 votes
1 answer
125 views

How to excite a fluorescent lamp without connecting it?

I'm a newbie in electrical engineering, so this might be a silly question. But are there any standard ways to create an electric field over a volume of air, strong enough to excite a compact ...
Dorian Appeldoorn's user avatar
4 votes
5 answers
20k views

How does a capacitor resist changes in voltage?

I was reading about how capacitors work and two sentences confused me: "A capacitor’s ability to store energy as a function of voltage (potential difference between the two leads) results in a ...
DigiNin Gravy's user avatar
0 votes
1 answer
113 views

Strong H fields: electronic items susceptible to thier damaging effects and how to shield them

This is another question related to magnetic fields. I'm trying to determine the thickness of copper foil that would be required to shield common electronic items from H fields of about 133 A/m over ...
dcorsello's user avatar
  • 321
0 votes
4 answers
545 views

What is voltage exactly? [duplicate]

First, let me start off by saying that I have read the answers to this question (which is the same as mine), but the answers basically explain the different ways voltage is created or compare it to ...
Lew Rod's user avatar
  • 69
0 votes
3 answers
6k views

How does the range of bluetooth increases by adding an antenna?

I have seen too many tutorials on how to increase HC-06 bluetooth module range. They all involve cutting the on-board antenna and adding an external one (a piece of wire or a 2.4GHz antenna). I was ...
idk's user avatar
  • 3
1 vote
3 answers
3k views

Disposable camera EMP coil not producing any field

I recently took on this project: https://www.youtube.com/watch?v=WIMhraVcdTg Trying to use a disposable camera as an EMP generator. I wrapped my wire around a bottle, but it still won't do anything,...
techset's user avatar
  • 61
1 vote
2 answers
99 views

Electric Field electrical charge

Hey i dont know how to solve this. Can somebody help me? In the two-plate arrangement shown in the sketch, there is homogeneous electrical field strength $$\vec{E_0} = -\vec{e}_y * 10\frac{kV}{cm}$$ ...
otto's user avatar
  • 167
1 vote
1 answer
150 views

Is Work done to Transfer Energy?

The example below is for a perfect lossless circuit with no resistance for the sake of illustration only. In reality this does not exist, but again the purpose is for simplicity. If there is 1 Joule ...
Marc Striebeck's user avatar
0 votes
1 answer
81 views

Does my electric clearing field actually make ions?

I am using an electric clearing field of 15v/10cm (~150V/m) to remove ions from a test chamber, however I'm wondering to what extent the localisation of the field's reference voltage plays a role. ...
Matt Stedman's user avatar
1 vote
2 answers
631 views

EMI Field Strength

I tried to look up this kind of question in the archives but didnt find much usefull information. I also have another question in regards to EMI but I will ask this later in a seperate post. ...
user3689010's user avatar
1 vote
0 answers
177 views

Equipment to measure strong constant (in time) and slowly changing electric fields

I would like to measure the electric field in the vicinity of an object of interest. I would like to have decent spatial resolution (i.e. be able to pinpoint a measurement to a point in space within ...
Slava P's user avatar
  • 133
5 votes
3 answers
746 views

How does current flow inside a grounded coax shield?

I have been trying to reconcile the fact that current flows on the inside of a coax shield with the common practice of grounding the shield. These ideas seem contradictory at the moment. For a 2-wire ...
Ian_B's user avatar
  • 51
2 votes
3 answers
274 views

Help me understand electrical fields better

I have a hypothetical scenario that would help me better understand (I hope) electrical fields and propagation of electrical fields better. So let's have a super simple circuit with one voltage ...
StjepanV's user avatar
  • 255
-1 votes
2 answers
87 views

Would the Electric Fields of simultaneously transmitted waves affect eachther

If there are 2 waves, with different frequencies, wouldn't the Electric fields add up and impact both waves regardless of the frequency difference? I attached a picture of what I mean, when there are ...
Rain's user avatar
  • 211
0 votes
1 answer
74 views

Find error in mathematical proof of electromagnetic fields

This is wrong but I can't figure out what is wrong, could someone help me find the errors.
Tina Hurlburt's user avatar