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.
44
questions
0
votes
6
answers
594
views
Transient analysis of inductor circuit and back EMF
In a lecture exercise from a circuit course, I encountered the following circuit with only an inductor and a voltage source. The \$v\$ vs \$t\$ and \$i\$ vs \$t\$ graph is as follows:
-The KVL ...
- 149
27
votes
13
answers
41k
views
How does an inductor store energy?
I know that the capacitors store energy by accumulating charges at their plates, similarly people say that an inductor stores energy in its magnetic field. I cannot understand this statement. I can't ...
- 783
15
votes
3
answers
4k
views
Does Shielding "Electrically" shield "Magnetically" too?
I know it sounds like a newbie question but I can't wrap my mind around it. An electromagnetic field is electric + magnetic field.
So this means that when shielding an equipment offensively, for ...
- 191
2
votes
6
answers
1k
views
Magnetron Working Principle
I was reading this simple description of magnetron working principle.
Can you explain me why when electrons go near the cavities, they start to resonate at microwave frequency? I do not see the link ...
- 3,580
0
votes
1
answer
288
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. ...
- 15
8
votes
5
answers
3k
views
Are there types of standard coaxial cable with a propagation velocity of 0.9c? What would be the application?
Reading this answer I was surprised to hear that there are "excellent" kinds of coaxial cable with a propagation speed of 0.9c; 90% the speed of light.
The bargain basement number is about 2/3c, and ...
- 3,459
4
votes
4
answers
632
views
Electromagnetic shielding and EMP
I've asked several related questions, but I'm afraid that some of the answers that I received, while great answers, might be skewed because of incorrect assumptions or unclarity in my questions.
The ...
- 321
4
votes
5
answers
3k
views
How can a DC spark create EM waves?
I have a question please about sparks used in the early history of radio. I have read the similar questions but I still need your help please.
I have learned from sources such as https://neurophysics....
- 71
4
votes
3
answers
1k
views
Can a slanted magnetic field be created with this insulated stranded wire arrangement?
I am considering building a small-scale experimental coil gun because I have an idea of how a magnetized projectile could be rotated while it is traveling through the coil(s), similar to how a bullet ...
user301910
3
votes
1
answer
8k
views
Difference between a magnetic field sensor and a hall effect sensor
I can't understand the difference between a magnetic field sensor and a hall effect sensor, to me are both the same.
I have a voltage detector pen that I can use when I troubleshoot my house I ...
- 1,547
3
votes
2
answers
1k
views
Propagation 'speed' of EM waves in air versus through conductive material
This paper I was reading said: "At a high level, the propagation speed of EM waves through conductive materials is SLOWER than their speed in air".
Don't conductive materials intrinsically have less ...
- 55
3
votes
2
answers
600
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 ...
- 31
2
votes
2
answers
261
views
Why does a loop antenna not measure the differential magnetic field?
I am making the assumption that a loop antenna is essentially an inductive loop and behaves as such, please let me know if this is incorrect.
Knowing that the voltage (emf) across an inductor is ...
- 107
2
votes
1
answer
723
views
Meaning of reflection coefficient in English
So I know a reflection coefficient of 0.5 angle 30 at the load (k=0m) means "At this point, 50% of the incident wave is reflected and has a 30 degree phase shift." But what does it mean in ...
- 199
2
votes
2
answers
10k
views
Is the resistance in a DC Motor constant if the voltage is?
Is resistance in a DC motor constant if both the load and voltage are constant as well?
- 25
1
vote
1
answer
5k
views
Homemade Electromagnet from Microwave oven transformer
I want to make an electromagnet in order to perform this trick
I have taken the following parts from a microwave oven, and following some instructions i have made the following electromagnet:
I have ...
- 113
1
vote
4
answers
297
views
Voltage on a Transmission Line with Ideal Conductors
Let's consider a transmission line with Perfect Electric Conductors.
We know that if an external AC source is applied, we get a voltage waveform between the conductors which is function of the ...
- 3,580
1
vote
2
answers
4k
views
How to increase an electromagnet's magnetic field size?
I made this electromagnet out of a microwave oven transformer by taking out the secondary coil. It very strong but it can only attract the metals if I bring it really close. How do increase the ...
- 13
1
vote
1
answer
1k
views
How to make the electromagnet of a magnetic-levitator?
I saw pictures of magnetic-levitators on the internet. That's amusing.
I wanted to make one of those. So I started searching in Google.
And I found out that these devices have a big electromagnet ...
- 818
1
vote
1
answer
234
views
Designing AC kick solenoid lock
I am making a kick solenoid lock with AC.
I designed the circuit to run on 220 V, 50 Hz (household plug.)
The inductor (coil) is air core
500 turns, 150 meter (500 ft) in length with inductive ...
- 69
1
vote
4
answers
456
views
Is ferrite core inductance similar to iron?
My 0.5" (1/2 inch) iron core inductor did not have a high inductance due to (I assume) eddy currents.
Theory seems to suggest that ferrite cores are the ticket to increase inductance.
I ordered ...
- 137
1
vote
2
answers
971
views
How is the current induced in this circuit?
Rectangle FBCE is the conducting wire. The circle is where magnetic field exists.The perimeter of the circle is NOT a conducting wire. R1,R2,...are different resistances.
If the magnetic field(B) is ...
- 115
1
vote
1
answer
307
views
Slow solution of LTSPICE electric-magnetic model for transformers
I am trying to model a transformer using coupled electrical and magnetic circuits. SPICE has many advantages in assembling these circuits. I was able to model properly for an transformer with no load, ...
- 1,380
1
vote
5
answers
881
views
Detecting a low pulse from an electromagnet induction
I am designing something similar to a coil gun. So what I have is a magnet passing through/adjacent to a coil. Due to the electromagnetic induction, I do get a pulse(triangular) across the coil. ...
- 2,386
1
vote
2
answers
239
views
Is .95J worth of work within 1 second Equivalent to .95W of Power?
This is a question that has two parts to it divided up into two sections. It is similar to the "Is Work done to Transfer Energy?" question but has been refined to include the conversion from Joules of ...
- 159
1
vote
1
answer
151
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 ...
- 159
1
vote
1
answer
290
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 ...
- 550
1
vote
1
answer
105
views
What are the mechanism and effects of non-linearity in an attenuating barrier in the presence of a high-strength EM field?
It's my understanding that in electromagnetics, if an attenuating device is functioning linearly, it means that 1) input and output signal strengths are proportional; and 2) input f = output f. How ...
- 321
0
votes
3
answers
261
views
Strength of a pulsed electromagnetic field
Forgive me if my question sounds a bit naive:
I have built a coil (no solid core) out of an insulated copper wire, and I calculated that it has 8 ohms of resistance. I tried it and it gave me the ...
- 61
0
votes
2
answers
197
views
Audio Engineer needed to read 14-track magnetic tape
I have a 20 mm magnetic tape, with 14 channels.
The data tape does not have any sound and format in which data has been stored on tracks is as follows.
The picture of tape head is as follows.
The ...
- 13
0
votes
1
answer
138
views
Accurately detecting distance from current carrying wire
I am trying to find a way to accurately detect the distance from a stretched wire for alignment purposes (within 10um). I am not concerned with the absolute value of the distance, rather the ...
- 15
0
votes
2
answers
1k
views
Find the current flowing in the load of a transmission line?
My Try:
\$Z_{in}=Z_0*\frac{Z_L+jZ_0tan\beta l}{Z_0+jZ_L tan\beta l}\$
Now
\$\beta l=\frac{2\pi\times37.5\times10^6\times10}{3\times10^8}=\frac{5\pi}{2}\$
so its becomes
\$Z_{in}=\frac{Z_0^2}{Z_L} \$
\...
- 484
0
votes
0
answers
61
views
What is the consideration when installing or replacing the shaft of an induction motor?
Here are two picture of my washing machine's motor. I am not sure whether you still have such that machine in your country. It is a top loading washing machine's washing motor (a another smaller one ...
- 291
0
votes
1
answer
6k
views
generator coils: max power given wire gauge
I've been messing around with some neodymium magnets and magnet wire to make a generator. I've rotated my rotor as fast as I could and noted the no-load voltage. I wondered if (at this current speed) ...
- 1,121
0
votes
1
answer
204
views
How to insert background EM noise into pathloss equation?
I am trying to understand how to add the background noise into the equation. I am trying to work out the pathloss of a radio signal over a certain distance.
We have the Friis Formula for that for ...
- 423
0
votes
1
answer
117
views
How do I correctly calculate the resistance (induced emf?) of a generated current against the flux? [closed]
I have all the basic physics working for every major section of the entire generator as correctly as I think I can (barring actual code implementation improvements) but just couldn't get the feedback ...
- 49
0
votes
2
answers
277
views
Simple wireless power transfer circuit question
source: https://circuitdigest.com/electronic-circuits/simple-wireless-power-transmission-circuit-diagram
Above circuit is the very simple wireless power transfer circuit, but I could not find any ...
- 457
0
votes
2
answers
261
views
What can I use to increase efficiency of inductive wireless energy transfer instead of factory manufactured ferrite plates?
The Context
I am a hobbyist with no education in electrical engineering. I am working on a DIY project trying to make water resistant rechargeable bicycle lights. I am doing this as a hobby for fun ...
- 113
0
votes
4
answers
3k
views
Phase of Scattering Parameters
I do not understand the meaning of the phase of scattering parameters.
Let's consider for instance a two port network, and let's focus on S21.
I know that its absolute value represents a ratio ...
- 3,580
0
votes
4
answers
398
views
Can a "static" magnetic field carry Information? [closed]
Information is electronically represented as some energy that is changing, therefore we measure an on state (1) and an off state (0), to create a (0,1) binary representation of the information.
Now a ...
- 191
-1
votes
3
answers
228
views
Magnetic Field vs E-M Field
I have got some questions on this topic based on the best answers I get to these:
-1- If magnetic fields arise due to electric currents in conductors, we say they are not E-M waves in nature; it is ...
- 207
-1
votes
3
answers
1k
views
Voltage drop through a resistor compared to a Zener diode
A variant of this question has been asked a few times, but not received a response. Usually, we get an analogy with water pressure, or gravity, or a version of Ohm's law; not the actual cause-effect ...
- 197
-2
votes
1
answer
490
views
Linear and non-linear attenuator
[edit 3/2/18] There are problems with the title and wording of this question. I would edit, but to do so would alter the relationship between the question and the answer that I accepted. So, I have re-...
anon
-2
votes
2
answers
246
views
Series RLC circuits
Suppose a series RLC circuit has its resonance frequency f_r. If we apply AC current of frequency f_r to this series RLC circuit then circuit has maximum current as output.
My question is little bit ...