Questions tagged [magnetic-flux]

The sum normal component of a magnetic field passing through a surface.

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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 (\$...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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-...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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. ...
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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. ...
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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 ?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...