Questions tagged [magnetic-flux]
The sum normal component of a magnetic field passing through a surface.
94
questions
2
votes
2answers
58 views
Magnetic force as a function of PWM frequency
Consider an experiement with a DC source feeding an coil with a constant DC current I. The coil with an iron core attracts a magnetic plate with mass m with force F. The force F is higher than Fm and ...
0
votes
1answer
37 views
How to calculate the emf with flux density given instead of flux
So I have the following question
What is the emf in a coil of 2000 turns and c-s area 10cm2 when a flux density of 0.4T density in it is reversed, i.e. in a time of 20ms. Also what would be the the ...
1
vote
0answers
41 views
Can we use the Halbach array configuration in an electromagnet?
I tried asking this question in several forums but didn't find any answers as i expected. It's very hard to find information about halbach array in google, especially in the electromagnetic field.
We ...
0
votes
0answers
39 views
How do I determine what magnet to use at a specific distance for a reed switch?
I have a reed switch that shows a 10AT to 15AT operate range on the data sheet. I need to determine if specific magnets will fire the switch, and at what distance.
The magnets I'm looking at though, ...
0
votes
1answer
49 views
Why does the V/Hz ratio of a motor affect the magnetic field strength?
When the frequency is increased whilst keeping the voltage constant, the magnetic field strength is going to weaken... I don't understand why and what actually happens that causes the field strength ...
1
vote
0answers
63 views
Inductance of a single conductor
Which is the correct expression for the inductance of a single conductor? I see 2 different formulaes for the same in different sources.
Formula 1.
Ref: https://www.eeweb.com/tools/wire-inductance
...
2
votes
3answers
86 views
From a flux point of view, how can we explain that the equivalent inductance is half when identical inductors are connected in parallel?
The equivalent inductance of 2 identical inductance connected in parallel ( ignoring mutual coupling) is half of the orginal . This result is usually derived from the argument of identical voltage ...
0
votes
1answer
26 views
Does magnetic flux depend on the orientation of the ferromagnetic rotor?
I have attached a picture of a reluctance motor setup. When I turn on the AC source, magnetic flux lines will build up.
My question is, will the magnetic flux will be a function of the angle turned ...
0
votes
1answer
20 views
Mean Free Path of Magnetic Core
I don't understand how they got the mean free paths (ls) of each leg. I know that I should be calculating the longest + the shortest paths and divide them by two, but I don't know HOW I should be ...
2
votes
0answers
36 views
Which capacitor in series with resistor circuit to reduce remanence effects of transformer?
The "Comparative Analysis of Mitigation Techniques for Inrush Current of Transformer" mentions "Pre-insertions resistor with capacitor method" as an inrush mitigation technique:
When circuit ...
1
vote
1answer
61 views
Pancake Coil Magnetic Field Strength
I am trying to measure the magnetic field strength of a pancake (flat) coil. I know the turns, inner radius, current, and frequency from an AC input and am trying to measure the magnetic flux so I can ...
1
vote
0answers
49 views
What's the name of the force that opposes the movement of magnet trough a coil?
I am trying to make an experiment that looks like this:
I am using this source https://physicshandson.wordpress.com/2019/02/04/damped-oscillations-in-mechanics-and-electromagnetic-induction/ as a ...
0
votes
1answer
46 views
Increase emf received from a coil without changing flux source
I have a situation where I'm trying to increase the amount of power received by a coil. To my understanding, I can increase the emf (voltage) by doing one of 4 things:
Increase the number of coils (\$...
0
votes
1answer
52 views
Field Flux control and Speed Of DC motor
I was studying electromagnetism and I tried to link with working of DC motors.
For the speed control of DC motor - The Flux of DC motor is reduced to increase the speed above rated speed.
I ...
0
votes
1answer
68 views
Electrical equivalence and Difference between Flux and Torque in AC motors
For AC motors, Synchronous and Asynchronous ones, are these two linked together or different quantities, namely magnetic flux and torque? Also if I want to measure these quantities electrically then ...
2
votes
2answers
52 views
Infinitely linear torque with current in motor?
I'm trying to find the maximum current my brushless DC motor can handle. If I can keep the coils and cabling cool (in a freezer right now), is there any other fundamental limit I may hit such as ...
1
vote
1answer
45 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 ...
0
votes
2answers
116 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
votes
2answers
92 views
Is a coil FM transmitter frequency affected by my body static?
I've built this coil FM transmitter following these guides which are essentially the same:
https://maker.pro/custom/tutorial/how-to-make-an-fm-transmitter
https://www.instructables.com/id/The-...
1
vote
1answer
56 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 ...
0
votes
1answer
52 views
Is it possible to determine a low power isolation transformer maximum output current?
I have a transformer (no codes) 240vac to 12vac this is easy enough to determine but what about the maximum current?
1) I could load it until the voltage drops but to what exactly?
2) Is there any ...
0
votes
0answers
25 views
Confusion regarding the right hand thumb rule
I am confused regarding the use of the right hand thumb rule . There is two use cases for this rule :
1- The first when the thumb points in the direction of the current the fingers points in the ...
1
vote
1answer
59 views
Shape of a core for use in a solenoid
I am currently designing an electromagnetic accelerator meant to accelerate a spherical nickel-plated NdFeB (neodymium) projectile along a circular tube, in a similar manner to a particle accelerator. ...
2
votes
1answer
136 views
Parasitic Inductance
when we say that in a wire there is a parasitic inductance, what is its cause? Is it the skin effect of the wire, the magnetic flux (generated by the current) through the surface of the total circuit ...
0
votes
2answers
82 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 ...
0
votes
2answers
108 views
What causes the residual magnetic flux when the current is zero in an inductor hysteresis curve?
An inductor with hysteresis has the following current versus flux curve:
I marked the point in red where the current is reduced to zero but there is still flux on the above curve.
What really causes ...
3
votes
2answers
345 views
Hall effect sensor as 2 wires switch
I need to find a way to make an on/off proximity detector triggered by a magnetic field, fitting in a small space of about 5mm ^ 3, and connected to the board by only 2 wires. I know a could use a ...
3
votes
1answer
231 views
What impact does winding tightly versus loosely have on transformer performance?
To make it simple (and actually, directly relevant to what I am working on): what impact does winding tightness have on transformer performance? Lets assume typical laminated EI / EE 60hz transformer, ...
0
votes
2answers
136 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 ...
0
votes
1answer
76 views
How can a magnetic circuit with an airgap have a higher e.m.f in the secondary coil than the same circuit without the air gap?
I have a magnetic circuit with the same configuration as in the image, the primary coil has 203 turns and the secondary has 406 turns, how do I get a higher eletromotive force when there is an air gap ...
2
votes
1answer
276 views
Estimate the Flux Linkage of a PMSM Motor
I'm not sure if it is possible to estimate the flux linkage of a PMSM motor (star connection) by the controller itself, where I can measure the input voltage, all the phase currents and the velocity. ...
2
votes
1answer
131 views
What is the purpose of perpendicular “smaller” magnets in between the main magnets in a rotor of a motor? had never seen this before. Do they help?
I am trying to build my own generator at home for fun, I saw on a video in youtube https://www.youtube.com/watch?v=YsSm65DAcCg where the guy placed smaller magnets in between the main magnets of the ...
-1
votes
1answer
299 views
What is the main difference between AC and DC generator basic working principles? [closed]
I cannot understand the main difference on AC- DC generator basic working principles.
Lets consider how a loop wire works with a magnetic flux inside a DC generator briefly. Whenever the sides of the ...
0
votes
1answer
33 views
Does a wider magnet mean less flux density?
I was using an online magnet strength calculator when I halved the diameter of the theoretical N52 magnet. The dimensions went from 32mm in diameter and 3mm thick, to 16mm in diameter and 3mm thick. ...
0
votes
2answers
113 views
Can I use rectified AC current to heat an object inside a induction coil?
The reason why I would like to use rectified AC is because I want to keep the magnetic field inside the coil unidirectional. A changing magnetic field induces current in the coil and vice versa. ...
0
votes
3answers
53 views
Magnetic field direction
How do I know the direction of magnetic field produced by a bar magnet, assume a electron present side to the magnet ?
1
vote
0answers
58 views
Scaling of magnetic field strength and flux density measurements and shape of hysteresis loop
Note: this is part of a larger question which I was asked to separate into subquestions.
Other subquestions: 1 and 2
I'm using the method outlined here to measure the induced magnetic flux density in ...
0
votes
0answers
63 views
Cutoff frequency of passive RC integrator used to measure magnetic flux density
Note: this is part of a larger question which I was asked to separate into subquestions.
Other subquestions: 1 and 2
I am using a passive RC integrator to measure the induced magnetic flux density in ...
1
vote
1answer
68 views
Buffering the input to a passive RC integrator used to measure magnetic flux density
Note: this is part of a larger question which I was asked to separate into subquestions.
Other subquestions: 1 and 2
I'm using the method outlined here to measure the induced magnetic flux density in ...
1
vote
2answers
216 views
Magnetic path length for partially wound toroidal transformer core
According to Wikipedia, magnetic path length is defined as "the effective length of a closed magnetic loop inside a magnetic core made of ferromagnetic material." Thus, for a toroidal core that is ...
-5
votes
1answer
167 views
Is there a difference between the radio magnetic field your body senses, from downloading 1 kB data from Wi-Fi router compared to 1 GB of data? [closed]
Imagine you have a Wi-Fi router and you're downloading 1 kB of data, if your body is receiving any magnetic field or signal from the router, what would be the difference if the router was sending 1 kB ...
0
votes
1answer
43 views
90 degrees phase shifted magnetic fields
If we have a closed magnetic circuit with two primary coils and one secondary coil wound on it. The primary coils are wound such that unlike poles are adjacent. Both primary coils are using rectified ...
0
votes
1answer
72 views
Lenz Law and Magnetic fields in an Inductor
Hoping somebody can set me straight on the magnetic fields involved in an inductor when the current is changing. This is how I see it:
The source current has a magnetic field.
This changing flux ...
2
votes
3answers
140 views
Why is the magnetic field around a bar magnet represented by iron filings?
Why would we use iron filings to display a magnetic field interaction and then teach this as the unaffected field of a magnet?
Iron affects the field itself. This is analogous to an observer ...
3
votes
4answers
684 views
Magnetic field strength and flux density from hysteresis curve
I am trying to measure the magnetic hysteresis curve of a toroidal nanocrystalline ferromagnetic transformer core made of Nanoperm (datasheet linked) using the following circuit. Each of the windings ...
0
votes
1answer
52 views
Is the conventional current direction assumed to be from - to + in US Air force training videos?
1)
https://youtu.be/a8casNPDvI4?t=354
I'm not sure if I'm misinterpreting, but I couldn't get past this point in the video as it seems they are assuming the current flows from - to + and its ...
0
votes
1answer
118 views
Can throwing charged capacitors cause magnetic fields?
Since current is just buckets of charge passing through a point in space per unit time, and a capacitor is a literal bucket of charge, I had some questions in mind.
Is throwing a charged capacitor ...
0
votes
1answer
66 views
Introducing third winding in Transformer
What would happen if I wind another winding (call tertiary winding with the same number of turns) on the transformer core and apply an AC voltage to it which is in phase with the primary voltage but ...
-4
votes
1answer
594 views
Maximum and Minimum flux in a coil [closed]
A coil of 100 turns and a diameter of 3.18cm is mounted on an axle through a diameter and is place in a uniform magnetic field, where the flux density is 0.01T, in such a manner that the axle is ...
1
vote
2answers
761 views
Metal detector coil SHIELDING?
Many designs of coils, of metal detectors, are shielded (Faraday shield).
Should this be used in a gravity-fed detector (like the sketched one)?
What's the shield for?
NOTE:
The coils are arranged ...
