Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [electromagnetic]

Electromagnetism, or the electromagnetic force is one of the four fundamental interactions in nature. This force is described by electromagnetic fields, and has innumerable physical instances including the interaction of electrically charged particles and the interaction of uncharged magnetic force fields with electrical conductors.

0
votes
3answers
59 views

The role of solenoid's wire diameter?

I'm not an expert in the electromagnetic field and need to design a solenoid actuator with 1 kg force approx. I am wondering if I change the wire diameter of the coil, what happens in solenoid's ...
0
votes
0answers
14 views

Can torque angle of motor be positive?

For any motor text say that, the rotor field follows the stator field with a certain torque angle. And in case of generator, the stator field follows the rotor field with a negative load angle. The ...
1
vote
3answers
153 views

Physics of Dirty Electricity? [closed]

I've been reading about "dirty electricity" lately and while I know there's much controversy whether it causes adverse health effects this question is not about that subject. I'm simply trying to ...
4
votes
1answer
45 views

Total current in a closed loop using Ampere's Circuital Law

I would like to reassure my concept on this question: I have 2 different ways to solve this question: Determining the direction of current in the loop using right-hand solenoid loop and adding ...
0
votes
1answer
45 views

Two modes of electrostatic force with charged capacitors?

During a charged state of a capacitor (Regardless of the type of capacitor), Simple parallel plate: .png Parallel plate with dielectric material in the gap: ]3 Supercapacitor: How is the ...
0
votes
0answers
24 views

Moving a capacitor in a time varying or non-time varying magnetic field?

1) If a simple parallel plate capacitor connected to a circuit, and discharging, were to move in an exterior magnetic field, what would happen to the interior region? Interior region components: ...
2
votes
2answers
101 views

Is it possible to convert the audio signal from a smartphone's headphone jack into radiowaves? [closed]

I was watching a video of someone using his smartphone and a custom designed coil to make a metal detector. The smartphone was connected to the coil via headphone jack. I couldn't understand how he ...
4
votes
1answer
72 views

Supercapacitor and an applied exterior magnetic field?

I'm curious of the effects of an exterior magnetic field to a Supercapacitor, in both states of charging & discharging. If the Supercap. is placed inside an area where an exterior magnetic field \...
0
votes
1answer
39 views

An electromagnetic wave incident on a closed loop

Consider the following diagram : Both the electric and magnetic fields will induce a voltage in this circuit. In more details, the component of the electric field that is in the plane of the circuit,...
0
votes
1answer
52 views

Electromagnetic Repulsion Coil Calculations

We have a 3x3 mm circular thin plate, which is made of copper, aluminium similar materials and thickness of the plate is 1 mm i.e. a very light and small piece of metal. To lift this plate about 2 mm ...
0
votes
0answers
38 views

Is there risk to using magnets on an enclosure that would have 1-2A wire assemblies leaving the enclosure

Would there be a reasonable risk to using magnets to close a large enclosure panel which has 3 motor drivers with wire assemblies that leave the enclosure to drive stepper motors? The motor drivers ...
11
votes
3answers
4k views

Do square wave exist?

If we send a square waveform through an antenna, will we get square electromagnetic waves with electric and magnetic fields looking like squares? Also, since there is an abrupt/almost jump in ...
0
votes
1answer
33 views

Coil output from variable magnetic field

If I put a coil with X Henry value and N turns in a variable magnetic field of Y Tesla peak value (coming from another coil excited by A sin(wt) signal), how to calculate the output voltage across the ...
2
votes
1answer
42 views

Transmission Line (shielded dual stripline )

Evaluate and illustrate: equipotential contours and a vector electric field distribution for . I got this result: and . I want to ask that, is the direction of the Electric field lines are correct?
0
votes
0answers
15 views

finding polarization of radiated far-zone electric field

I am given a question in which I have to find the polarization of the radiated far-zone electric fields when phi is 0 and 90. Why are the following formulas used respectively? For phi = 0 $$ E_\...
0
votes
1answer
110 views

Not able to levitate magnet for magnetic levitation project

I am following a hackster project on magnetic levitation here - https://www.hackster.io/jsirgado/magnet-levitation-with-arduino-eeeee4 However, I have followed everything but still, it's not working. ...
2
votes
0answers
89 views

Why is energy maximized in an air gap?

Suppose we have an air gap problem like in the picture above. Now the induced MMF will clearly move the object in the negative x direction. It will do this because energy is maximized. Due to coenergy ...
0
votes
2answers
114 views

Why is wireless charging safe for phone circuits? [closed]

Wireless charging is done by electromagnetic induction, by continuously changing magnetic field in a coil, i.e. by passing AC current through it. I have always been told by others to keep magnets ...
0
votes
0answers
41 views

Find force pull solenoid

Sorry for the previous post that was wrong. I want to knowF=(NI)^2*μ0*A/2L^2 A What is the cross-sectional area? NewRef.https://www.researchgate.net/publication/...
2
votes
0answers
42 views

How does a electropermanent magnet work?

I’m trying to wrap my head around electropermanent magnetism. I read this wonderful PhD Thesis by Ara Knaian as well as details the history of this concept as well as Kyle Gilpin, Ara Knaian, and ...
3
votes
1answer
42 views

What's the circuit diagram symbol for a variable reluctance sensor transducer?

I know I've seen the symbol before, it's something like a circle with an open triangle facing in the direction of current flow with a line through the middle. I'm specifically thinking of the ...
1
vote
4answers
67 views

How is electromagnetic interference possible when measuring voltage difference?

This question is primarily concerned with audio but it's probably applicable to other areas as well. As far as I understand, EMI is caused by electromagnetic waves adding power to wires as they ...
16
votes
4answers
4k views

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 ...
2
votes
1answer
82 views

Why does adding more coils make my electromagnet weaker?

I've built a couple of simple electromagnets, using a nail (not sure of the material) and copper wire connected to a 1.5V AA battery. I'm really confused because the electromagnets with less coils are ...
1
vote
1answer
103 views

Treadmill causes nearby electronics glitch

I don't know if it is right place to ask, if not correct/guide me. I recently have built treadmill workstation, where I could walk and work (rather than just sitting). But as soon as I turn on ...
0
votes
2answers
69 views

How do I convert the units of a moving magnetic field to volts?

Copper wire wrapped around an iron core produces current when a strong magnet is moved in its vicinity. I gather the "magnet movement" part is expressed in units of "weber" (kg⋅m2⋅s−2⋅A−1) or perhaps ...
1
vote
0answers
22 views

Which power converter topology has higher benefit of EMI/EMC?

Which power converter topology can be best suited for EMC compliance for small power converter to be used in LED lighting products. In my context I'm using a 5W non-isolated AC-DC converter which is ...
0
votes
1answer
57 views

Magnetic material demagnetization through Curie temperature

It is known that some materials lose their permanent magnetic properties when they are heated above certain temperature known as Curie temperature or Curie point. As those materials are cooled down to ...
0
votes
4answers
103 views

Sinusoids represented using Euler's formula notation, confusion

EM plane waves are represented using the equation (ignoring amplitude) $$E(x,t) = e^{j (wt - kx)}$$ They are also represented in this form: $$E(x,t) = \cos(wt - kx)$$ I want to get the electric ...
1
vote
2answers
63 views

Learn how information is transmitted

Maybe this is not the right place to ask this, it is so, please tell and I will delete this question. I want to learn how information is transmitted using radio and TV. I want to learn that because I ...
2
votes
1answer
145 views

How to generate a high energy electromagnetic wave? Using high voltage or high current?

I am about generating an electromagnetic wave which should be powerful enough. So I should manipulate its electric field and magnetic field simultaneously. As far as I know E amplitude depends on the ...
0
votes
2answers
45 views

Magnetic Flux loss in PM Motors

The PM motors specially BLDC or PMSM they get their armature energy from the permanent magnets on their rotors unlike the Induction Motors in which the armature gets its energy from the Stator ...
2
votes
1answer
93 views

Contradicting ideas about differential signal route, confining fields vs Increasing impedance

By initial sense I think we must: keep pair intra-distance as close as possible for field cancellation. Fill surround of pair with GND plane and have via near to it to confine the fields, prevent ...
2
votes
2answers
96 views

“Electromagnet 5kg DC 3V 5V 6V 12V” - what do these multiple voltages mean?

I wanna buy an electromagnet from aliexpress and many of them are lifter magnets and have 6V, 12V, 24V and 5kg. So if i choose the 6V option does that mean the magnet can lift 5kg at 6V? Why would ...
0
votes
0answers
52 views

Why aren't homopolar generators more commonly used?

In particular with the advent of HVDC(high voltage direct current). Using mercury(metal), the resistive losses can be greatly reduced. There has even been some experimental research into neon plasma ...
0
votes
0answers
27 views

Air core design

what is the appropriate air core design for inductive power transfer that is suitable for 30khz? I used 200 turns and 7 inches diameter.
0
votes
1answer
53 views

What happens in a generator so that we get a sinusoidal voltage as an output?

I read this online, " For a travelling magnetic field in a circle, the induced magnetic field in the armature of the generator will be sinusoidal. That's why the generated voltage is a sinusoid, ...
2
votes
0answers
69 views

What it the base technology used in electronic speaking pens?

I am interesting to learn more about the technology used in electronic speaking pens which can be found as education toys for small children. When the pen is placed over a book illustration or text, ...
-1
votes
3answers
135 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.
0
votes
2answers
212 views

Explain this circuit

I know this circuit is an oscillator circuit and it senses another signal of same frequency, but I don't understand the calculation behind it, and the reason for emitter inductor, 3.9k collector ...
0
votes
1answer
161 views

Practicality of using flat-spiral coil as electromagnet?

For my project, I'm using a 3D magnetic sensor to track the proximity of a local electromagnet at any time, no more than a finger length away. Ideally, I would like the the electromagnet to be: ...
-1
votes
1answer
31 views

How to determine direction of induction current (I inc) according to V emf?

In this question, I easily understand the solution. But I want to determine the direction of induction current (I inc) with the Lenz Law. I know how works Lenz Law, but I couldn't determine the ...
0
votes
2answers
63 views

Determining magnetic flux density of a closely wound toroidal coil

I am using David K. Chengs's Fundamentals of Engineering Electromagnetics book. In chapter 5/question 5.2, there is a given closely wound toroidal coil, and it asks what is the magnetic flux density ...
1
vote
1answer
85 views

How to convert A/m to dBμA/m?

Lets say I have -2 dBμA/m as a limit. How do I convert the magnetic field strength in A/m to dBμA/m? Is it as follows? $$20\cdot \log(\frac{ |H| }{10^{-6}})$$ Thank you!
0
votes
2answers
115 views

Why does my laptop emit electromagnetic radiation when charging (only)? [closed]

I have an electromagnetic radiation detector that I've been playing with recently, going around the house and testing various appliances, and I noticed something weird. When I charge my laptop (or ...
1
vote
1answer
77 views

Current flowing through copper wire?

I am a grade 12 student, working with electromagnets for a physics project. My equation requires me to measure the current of a 20-25 cm bare copper wire 18 gauge. The power supply would be an aaa ...
0
votes
1answer
119 views

Can a magnet cause a microwave oven to unsafely radiate energy?

I've already successfully warped the colors on a large old CRT Television by setting unshielded speakers on top of it. If I understand correctly, this was due to the deviation of the electro-magnetic (...
0
votes
1answer
414 views

Calculating number of coil turns for a generator

I'm building a generator for a school project. I'm planning to use N42 neodymium magnets with performance of 5100 Gauss, How do I calculate what diameter of copper wire I need to make the coils and ...
1
vote
1answer
55 views

Is EMF induced in a conducting loop moving in a uniform magnetic field with uniform velocity perpendicular to the magnetic field?

Due to the the magnetic force= q(v × B), the separation of charges must take place. One point must be at high potential than the other. So can't we just take the separation of the charges as the ...
0
votes
3answers
81 views

RFID: Why is inductive coupling used instead of EM waves for LF and HF systems?

Is it because of antenna sizes? At 900 MHz a 1/2 dipole has a size of around 15 cm. That would be far higher for 125 kHz, so instead we use coils to power the transponder and use load modulation for ...