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.

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88 views

How can I generate a noisy environment to test my PCB?

I am developing a PCB project but i want to use the PCB in noisy environments (which usually contains 7.5-45 kW multiple motors with frequency inverters and also ignition transformers). I made some ...
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Why is it said that for efficient transmission of radiation, antenna size should be comparable to wavelength of the radiation? [closed]

I have found it across many texts but I am confused about the reason why is it so? Is this related to radiation resistance?
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Can we apply the equivalence principle in electromagnetics to multiple regions simultaneously?

Setup 1 An object \$(\epsilon, \mu)\$ occupies volume \$V_1\$ and is enclosed by surface \$S_1\$. It sits in vacuum \$(\epsilon_0, \mu_0)\$, denoted by \$V_0\$. In \$V_0\$ there is an electric field \...
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19 views

High speed switching electromagnet control circuit

I am not very familiar with high speed switching magnets, and need help finding a control circuit that has adjustable frequency and duration for High Rate Switching Electromagnets, with a digital ...
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50 views

DC Chopper Operation in SMES Design

I'm reading a paper on a superconducting magnetic energy storage (SMES) power control system. One large superconducting inductor (L1 in the figure below) is charged up by a 10kA power supply. Once ...
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2answers
88 views

Why is magnetic field not accounted for in the theory of CRO

I’m reading the chapter on Oscilloscopes in Cooper’s Electronic Instrumentation and Measurement Techniques. Nowhere in the theory of the working of CRO (like deflection sensitivity) does he take into ...
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66 views

Momentary Over-Excitation Voltage Circuit

I want to control an electromagnetic brake (fail-safe brake) used along with servo motor. Microcontroller will control the trigger signal for the electromagnet coil. Electromagnet Requirements: ...
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81 views

How am I supposed to calculate the half power beamwidth of antenna (HPBW) from radiation intensity?

I know we should set the U equation = 1/2. But am I wondering should we just set the cos^4(theta) = 1/2 or the whole equation including the constant number 200 i.e. 200cos^4(theta)=1/2 to solve for ...
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Guided propagation in transmission lines

Can you help me on understanding why we may say this transmission line the propagation is guided and there is not any radiation? It is a 2-conductors transmission line, in which the conductors are ...
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19 views

Power Radiated by an antenna

I have read that the power radiated by an antenna is equal to the flux of the Poynting vector through any closed surface that includes the antenna. This fact is for instance exploited to calculate ...
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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 ...
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Avoiding signal interference in a cable that carries video signal and sensor signal

I am using a 6 core shielded cable. In this 3 wires are used for a sensor and 3+1(shield) is used for a analog camera. All the cores take DC supply. Sensor(3 wires) (+)24 volt supply, (-)minus, ...
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Microstrip propagation mode

I have a trivial question about EM propagation in a microstrip line. Why do the electric and magnetic fields have the following lines? Which are the physical laws (Maxwell etc) for determining them? ...
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Why is a clamp meter unaffected by nearby wires?

I understand a clamp meter works by measuring the magnetic field generated by current flowing through a wire. It's well known that clamping 2 wires carrying the same current in opposite directions ...
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Steel vs iron for linear solenoid plunger

How much more force would an iron plunger provide than a steel plunger? From what I’ve read it seems like it would be much better, but I have no idea where to buy an iron rod. Also, how much of an ...
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Marchand balun layout

For this marchand balun schematics in ADS, how to instruct the ADS layout generator to use coil shape (for area saving in IC) ? Besides, anyone have any experience with planar layout of marchand ...
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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 ...
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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 ...
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216 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 ...
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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 ...
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1answer
66 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 ...
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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: ...
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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 ...
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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 \...
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40 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,...
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70 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 ...
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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 ...
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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 ...
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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 ...
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49 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?
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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_\...
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118 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. ...
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107 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 ...
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116 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 ...
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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/...
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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 ...
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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 ...
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4answers
69 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 ...
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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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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 ...
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109 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 ...
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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 ...
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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 ...
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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 ...
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115 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 ...
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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 ...
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1answer
161 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 ...
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2answers
48 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 ...
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1answer
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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 ...
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“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 ...