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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35 views

Quarter-wave impedance transformer working principle

consider the following scheme: A transmission line of length lambda/4 has been put before the load ZL in order to get an impedance matching. But, I do not understand how it works. Precisely, by the ...
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1answer
73 views

what if the two wires of a single twisted pair are different in length?

For example, one wire of a twisted pair is longer than the other wire (imbalance starts from the middle of the twisted pair, everything is balanced before the middle point). What problems will it ...
2
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1answer
57 views

Radar and Standing Waves

I have a doubt about the working principle of a simple Radar. Consider a stationary object, which does not move with respect to our transmitter. We send an electromagnetic wave to it, and it will ...
4
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2answers
86 views

Why is the the permeability of a ferromagnetic material given as B/H not it's slope dB/dH?

I was going through my Electromagentics book by Sadiku where it was mentioned as a point that permeability of ferromagnetic material is given by the ratio of B(magnetic flux density) to H(magnetic ...
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4answers
126 views

Is the curl of a B field at a point on a wire infinity?

According to this text, curl is defined as a limit of the surface area approaching zero. If the point where the curl is evaluated at is near the wire, B is evaluated at a decreasing r value, and ...
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0answers
49 views

Magnetic lens supplier [closed]

What companies sell magnetic lenses? Google searching yielded no results for magnetic lens suppliers. My application is pricing out a TEM.
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2answers
191 views

Am I exposed to high levels of radiation at my job? [closed]

I made this post because I have a safety concern about my job as medical device tester. I was reading the user manual of the equipment I work with and found the next warning: “Per FCC regulations, ...
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1answer
43 views

demagnetising a magnet with a high frequency transformer

This is a theoretical question. Some elements described in the problem may be impossible/impractical, but I am just trying to understand the principles. It is kind of a physics question, but also ...
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0answers
12 views

HFSS SAR anlysis Calculation

I am calculating The SAR anlysis on a human head of a wearable antenna that i have made . I have added a waveguide port and after simulation it does not show the radiation pattern using the HFSS ...
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1answer
63 views

How to transmit a signal to a point [closed]

I have a signal generator (Digital Dual Channel Funktion Signal Generator) and want to generate two signals (530 and 550 Khz signal) and want to transmit these generated signals to the points on a ...
0
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2answers
69 views

Can a change in magnetic field change the impedance of a coil

I kept a coil in a linearly increasing magnetic field and calculated the impedance by measuring the induced current and voltage. When the maximum value of magnetic field was reduced (while keeping ...
0
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1answer
52 views

signal propagates in bending transmission line (unequal length between signal path and return path)

Suppose I have a square wave signal generated from a signal generator and its outputs are connected to the two terminals of a paired PCB traces (left side of the picture below). The other end of the ...
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0answers
20 views

How flux density increases in the dielectric medium?

The above figure shows a polar dielectric medium in an external electric field which is normal to it's surface. From the equation of D(electric flux density) we see that flux density increases but ...
2
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1answer
90 views

Inconsistent readings between oscilloscopes

I have a circuit that pulses a high frequency EM field at a rate of 2Hz. I'm trying to see the accuracy and precision of the circuit, but I see very different readings on two oscilloscopes I'm using: ...
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0answers
26 views

Antenna Polarization understanding

I am trying to design a Circular polarized Antenna. We know that the criteria for a circularly polarized E-field : The E field should have to components The two components should be equal in ...
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1answer
18 views

PEC-backed dielectric material

For the paper named "Antenna Miniaturization and Bandwidth Enhancement Using a Reactive Impedance Substrate" the statement "PEC-backed dielectric material", so what is the meaning of this statement? ...
1
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1answer
37 views

Lorentz force of a conductor loop

I have a task to solve in electrodynamics, I have really no clue how to solve. Would be very thankful if someone could help! There is a live conductor loop L, which is situated in a magnetic field B. ...
2
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3answers
235 views

Making a electromagnet

Can a insulated wire be used to make a electromagnet? Will there be any difference in strength of the magnet if I use an uninsulated wire instead? By uninsulated wire I mean this:
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1answer
28 views

Field geometry of external magnetic core?

If there is a coil with an external core, would the polarization of the magnetic field inside it be the opposite of an internal core? For example, in the image: If DC current were applied to the ...
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3answers
172 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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0answers
21 views

current transformer and primary positioning inside window

I am designing a setup that is a little convoluted. but it's on purpose. The point is to make a toroidal current transformer act as an electromechanical pickup. Just for musical experimentation and as ...
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0answers
74 views

How can I measure the actual magnetic strength of my electromagnet to compare against my calculations?

I am interested in building small scale electromagnets and I wanted to measure their actual magnetic strengths to compare against my calculations. What are possible ways to measure the difference?
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0answers
48 views

Tuning antennas

I am working in a biomedical implant. I have to design an antenna for the wireless power transmission. The frequency that I am using is 13.56 MHz. I used some antennas found in some articles but when ...
0
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1answer
67 views

Eigenfrequency of a toroidal resonator

All units are in the SI I'm doing my task from vacuum electronics - for the given klystron with a toroidal resonator[ Resonator: I have to find the $h$ parameter, that will satisfy given ...
0
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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 ...
2
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1answer
59 views

Measuring the orientation sensitivity of a UHF RFID transponder, where do the deviations come from?

I measured the orientation sensitivity of a UHF RFID tag using a Voyantic Tagformance Lite RFID test device. I rotated the tag along the 3 axes using a stepper motor and a rotating table. The ...
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3answers
102 views

What happens in real and how is it modelled when electric and magnetic fields couple to this simplified circuit?

I’m trying to make the question clear by simplifying a single ended circuit as a constant voltage source is coupled to a measuring device such as a scope or an ADC ac below: The source V1 above has ...
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0answers
32 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: ...
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1answer
37 views

Leakage Inductance Coaxial Cable

I do not understand how a particular parasitic effect is model. I have read that on a coaxial cable there is a problem due to the fact that the external conductor's magnetic field crosses the air ...
2
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3answers
53 views

If a PEC surface completely reflects an EM wave, why doesn't an ungrounded shield work?

I was thinking about shielding and its effectiveness. An ungrounded shield doesn't work well for either inductive or capacitive coupling. However, if you think about plane wave theory, a PEC surface ...
3
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3answers
100 views

How to make a motor capable of resisting physical movement?

Is it possible to make a motor capable of resisting physical movement? For example, at the gym you control the resistance to movement by putting more load, more weight. Is there a way to control that ...
0
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1answer
69 views

Could shielding (not grounded) affect signal integrity?

I'm trying to shield 6 flat cables that give me some communication issues because I thought that there might be cross-talk or other sources of interference that cause the problem. The shielding is ...
4
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1answer
74 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 \...
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0answers
19 views

Design/Simulation and on-chip microfabrication of a 2D/thin-film bias tee with narrow bandwidth around 200 MHz

What is necessary and a possible design to realize a bias tee for on-chip integration and the AC electrical connection of two 200 MHz nano-rf-oscillators (both DC-fed with 1-10 mA) and creating an AC ...
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1answer
53 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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2answers
82 views

Is there a motor design where a rotor gradually moves into a stater? [closed]

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 over the rotor, but the primary motion is rotary,...
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3answers
66 views

Copper wire current ratings [duplicate]

I have seen a wide variety of different estimates for the maximum current rating for copper wire. For example, for 24-gauge copper wire, the Wikipedia article about "American wire gauge" claims that ...
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4answers
43 views

How do you drive a variable reluctance stepper/SRM as a generator?

I think I understand the principles, even if not the details, of operating a VR/SRM as a motor. But I don't understand, and can't find any good explanation online of, the principles for how to use one ...
0
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1answer
27 views

Is a one-stator reluctance motor possible?

Often when the magnetic field of reluctance is pictured, one sees a "flow" from one stator to another across the rotor. I'm wondering if it is possible to have a reluctance motor with only one ...
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0answers
30 views

How to stabilize the magnetic levitation system? [duplicate]

I have asked similar question before also but want to try again - Not able to levitate magnet for magnetic levitation project I followed everything from this project but still, the magnet is not ...
0
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1answer
42 views

Can I use a power supply to power a solenoid electromagnet?

I've got several unused coils of 14 gauge wire that have ferrite iron cores cut to the length of their spools. They have maximum current power transmission ratings of ~5.9A, and according to a ...
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0answers
40 views

Problem based on Laplace and Poisson's Equations. How to find the charge from electric field and potential?

In the above problem, I have found out the potential and the electric field in the medium between the two conductors. From here, how can I calculate the approximate charge per plate?
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0answers
64 views

Given the vector current density, determine the total current flowing outward through a circular band

Given the vector current density, determine the total current flowing outward through a circular band.: The answer should be 518A. It comes something around 3255 A. Where is the mistake?
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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/...
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1answer
75 views

What is the major difference between the Telegrapher's Equation and the transmission line equation?

I am confused on when you would use the telegraphers equations vs when you would use the transmission line wave equation. Telegraphers equations: Transmission line wave equations:
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1answer
55 views

Reflection of Electric field in open-circuited transmission line

Consider a parallel-wire or parallel-plate or coaxial transmission line, carrying TEM wave, which we model as E,H,V,I, each having a forward(+) and backward(-) wave. In terms of V,I, we define ...
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1answer
51 views

Different printed circuit layout for a transistor

The below figure shows a schematic for a transistor where there exists an external magnetic field : This schematic has two layouts to choose from. The first one is shown below : The second layout ...
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0answers
44 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
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1answer
43 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 ...
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3answers
56 views

Why current flows along a transmission line?

Say I don't have a ideal transmission line i.e resistance/length!=0. Also E-Field exists between the two conductor lines. How then current flows through the line? There is no E-Field along the line ...