Questions tagged [magnetic-flux]

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

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29 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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2answers
70 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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2answers
48 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
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 ...
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1answer
45 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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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 ...
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1answer
37 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
61 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
71 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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71 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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2answers
158 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
128 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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16 views

Inverse LUT of flux-linkage maps for PMSM

I've been given the LUT of the flux linkages for an IPMSM in the dq-domain. \$\lambda_d = f_1(i_q, i_d)\\ \lambda_q = f_2(i_q, i_d)\$ The maps are obviously non-linear. The sampling has been done ...
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2answers
72 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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1answer
67 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
157 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
125 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
227 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
31 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
95 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
48 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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0answers
48 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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48 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
55 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
141 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
166 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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22 views

Problems in simulating current model flux observer

I want to estimate rotor flux in 3 phase induction machine using Blaschke's equations. Here's the current model I'm suppose to simulate.:. I have to simulate this thing, I successfully obtained iqss ...
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1answer
38 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
63 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
125 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
508 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
51 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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1answer
104 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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1answer
62 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
422 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
535 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 ...
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1answer
61 views

Flux control in transformer

What would happen if I apply a voltage (same phase as primary) to a tertiary winding wound over the transformer core? Would the mutual flux change or would the primary draw a different value of ...
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1answer
222 views

When to use a Hall probe and when a fluxgate magnetometer to measure magnetic fields?

I am familiar with how the two methods work, but what applications are more suitable for one rather than the other? I have seen this question but I don't think it covers my point.
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1answer
106 views

How does this dynamo work?

I disassembled a dynamo-fuelled torch and I found this set-up. Now, what I know is that the led should be lighted up by the electromagnetic force generated by the time-varying flux within the coil. ...
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96 views

Flux control of transformer

Can the flux (not flux density) of a transformer be controlled so as to achieve constant voltage output with varied loads? For example, increasing the flux slightly when the load is high.
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1answer
187 views

Why my In-wheel BLDC Motor have sinusoidal back emf (line to line) when rotate by external system?

I have In-wheel BLDC motor having 46 poles (Permanent Magnet)on rotor and 51 slot in stator. When I used an external machine to rotate my in-wheel BLDC motor, then measuring across two phase back emf ...
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2answers
265 views

why in-wheel BLDC motor have more pole than normal BLDC motor?

I am using a In-wheel BLDC Motor having poles 46 but another normal BLDC motor have less pole as 8 pole. I have searched about other In-wheel BLDC motor and it also have 42 poles.
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1answer
106 views

Electromagnet flux density calculation knowing specs of coil, core and applied voltage?

Seems to be almost a textbook task from a freshmen class. But I am truly puzzled. Electromagnet has a coil of tightly wound 100 turns of copper wire around a cylinder core with relative permeability ...
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1answer
143 views

What parameter is used to choose the direction of the flux in a magnetic circuit?

I don't get why the \$\Phi_{1}\$,\$\Phi_{2}\$ and \$\Phi_{3}\$ are supposed to be running in the way depicted here.
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1answer
40 views

Skin effect and mag field distribution inside an electric conductor

Magnetic field inside a current carrying conductor Suppose I took a circular current strip in a current carrying wire. At the centre I have marked the directions of magnetic field due to four points 1,...
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0answers
53 views

magnetic field, resistance and inductance of the coil

i have a coil wound ready. I need to find the magnetic field, resistance and inductance of the coil. can someone tell me some simple circuits to find it? And how to find the field using a pickup coil?...
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90 views

Why the shape of rotor-poles of salient pole synchronous machines are designed as sinusoidal in shape?

I knew that this is done to eliminate harmonics. But I couldn't get its reason. So I am confused whether my conclusion was right or wrong.
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937 views

How can increasing the voltage/frequency ratio of an induction motor result in magnetic saturation?

The information below pertains to an induction motor: The magnetic capacity of the motor's magnetic (iron) circuit is designed to the relationship: voltage/frequency (V/f). If the frequency ...
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71 views

What is the internal linkage flux of a wire with radius a(shaped like a cylinder)

How can we clarify that the relation between linkage flux an flux in a cylinder shaped wire is \$ d\lambda=\frac{x^2}{a^2}\ d\phi \$?can we illustrate this by electromagnetic formula?I think I would ...
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1answer
75 views

Measuring Low Magnetic fields

Im working on a project where I want to measure low magnetic fields in a wire. The range I want to measure is 0.1 - 10 mG or 0.01 - 1 µT in low frequencies (DC - 500Hz) (This range (0.1 - 10 mG) can ...