# Questions tagged [field-strength]

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### Maxwells Equation in Time varying field

The Maxwells Equation giving the value of Magnetic field (B) for stationary and moving coils are having different variables. How is the third equation possible with such 2 cases?
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### how do we get these three formulas from the definition? field strength

I believe these three equation in the figure are not the definition of field strength,and the definition of field strength is $H=\frac{F}{m}$,how do we get these three formulas from the definition? ...
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### Conductor loop magnetic field in the middle

Why I have to take in the formula $H = \frac I l$ the diameter and not the radius of a conductor loop when I want to know the magnetic field-strength in the middle of it. I have a conductor loop ...
62 views

### When a coil is wrapped around a ring of non magnetic material, is the path length (l) the circumference or the diameter of the ring?

I'm doing some practice questions on magnetic fields: A coil of 300 turns is wound uniformly on a ring of non-magnetic material. The ring has a mean circumference of 40cm and a uniform cross-...
53 views

### induced voltage in coil due to moving magnet

I am trying to calculate the voltage induced in a zylidric coil by a moving permanent magnet that is placed near the coil. To simplify calculations, assume that the permanent magnet is also a zylinder ...
139 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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### How strongly does patient movement affect the magnetic field in an MRI? [closed]

The magnetic field in an MRI is insanely stable due to a closed current loop in the superconductor. A normal conducting magnet would always have (in addition to a ridiculous power consumption) power ...
109 views

### Electric field strength from AC conducting wire in form of a loop along z-axis?

Let's say I want to calculate the electric field strength from an AC conducting wire, with a certain frequency and current. The wire is in the form av a loop. I want to calculate the E-field along the ...
160 views

### How to convert A/m to dBμA/m?

Lets say I have -2 dBμA/m as a limit. How do I convert the magnetic field strength in A/m to dBμA/m? Is it as follows? $$20\cdot \log(\frac{ |H| }{10^{-6}})$$ Thank you!
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### 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. ...
416 views

### How can I measure AC magnetic field using linear hall effect sensor with the arduino?

I have a SS49E hall effect sensor. I want to measure magnetic field in gauss using arduino analog output. I have a code for analog application but is this appropriate just for the dc magnetic field ...
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### 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 ...
90 views

### Skin effect of copper in a high-strength AC magnetic field

I'm trying to determine the thickness of copper foil required to construct an enclosure that attenuates a very fast-rising, very brief pulse of AC magnetic field at a frequency of 1 MHz and field ...
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### Energies of the fields in a plane wave, attenuated and unattenuated

This is a combination of two of my previous questions (question 1 and question 2) which are related. I'm trying to learn both how energy is carried in the electric and magnetic components of a plane ...
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### Energies carried by electric and magnetic fields in plane waves

This is a newbie question. I'm trying to understand what I think must be a very basic concept with an obvious answer, but I want to be sure. Do plane wave electric and magnetic fields of equal ...
1k views

### Small SMD components: are they really capable of withstanding high voltages?

You can easy find some SMD components which are pretty small for such a high voltage (500V @ 0805 package for example - crazy?!). 0805 case would have 1.3 mm distance between the contacts, so I doubt ...
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### Electric Field electrical charge

Hey i dont know how to solve this. Can somebody help me? In the two-plate arrangement shown in the sketch, there is homogeneous electrical field strength $$\vec{E_0} = -\vec{e}_y * 10\frac{kV}{cm}$$ ...
369 views

### Calculate work done to remove a electron at the above position from nucleus to infinity

i'm doing this question and I'm at the last part now. The first question wanted me to find out the electric field strength (r= 3.0x10^-10m, q= 9.6x10^-19C) and i used coulombs law and i managed to get ...
279 views

### EMI Field Strength

I tried to look up this kind of question in the archives but didnt find much usefull information. I also have another question in regards to EMI but I will ask this later in a seperate post. ...
75 views

### How to calculate electrical power needed to produce a given electromagnetic RF field?

What Electrical Power (watts) needed to produce the electromagnetic RF field intensity (strength) ≈ 60V/m? How to calculate electrical power needed for a given electromagnetic field strength value? RF ...
133 views

### Equipment to measure strong constant (in time) and slowly changing electric fields

I would like to measure the electric field in the vicinity of an object of interest. I would like to have decent spatial resolution (i.e. be able to pinpoint a measurement to a point in space within ...
213 views

### FSPL formula for near magnetic field?

I would like to know the precise formula for the Free Space Path Loss in case of a Magnetic Field in the Near Field region. We all know the popular FSPL formula, but this is only for the far field, ...
2k views

### EIRP and Radiated Field Strength

I have a question regarding Field Strength: I was told it is independent from the frequency, is that true? If so, why? Moreover, I came accross this equation for converting the Field Strength to ...
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### Calculate field strength for shielded isotropic transmitter

How to calculate the field strength of a shielded theoretical isotropic transmitter, if there is a hole in the shield for example. I am looking for a complex formula that also takes into account the ...
204 views

### How to transform field strength as a function of frequency

According to the EN 55022:2006 standard max electric field strength should be: 40 dBμV/m for 30–230 MHz 47 dBμV/m for 230–1000 MHz I am a little bit confused, I don't know how to calculate the ...
2k views

### Formula for Field Strength

According to this document on page 3, the formula for Field strength is stated as follows: I can't find reference to this formula elsewhere and was wondering if someone can verify this is correct, in ...
181 views

### IR signal strengh measurement

I have an application where I have multiple IR transmitters/receivers set up to read data. These are removable and can be set up in a lab environment where I can control distance, light, etc. I've ...
376 views

### Relationship between electric field at aperture and field at distance

I'm new to this forum and turned here because I have no other help to turn to. In studying antenna theory and I came across the relationship between E0(Electric field at aperture) and Er(Electric ...
424 views

### Measure AC magnetic field strength between 100kHz and 300 kHz

I have tried to find in the webpage some answers about measuring AC magnetic field strength in the range above 50 kHz and more with no luck. Sorry, but if someone could help me will be great. I need ...
8k views

### Conversion from dBm to Volt/ meter

I have no experience with electronics but I have a question. Actually I'm using a circuit for a project that is able to measure RF power at its input in dBm; the circuit provides the integration of a ...
669 views

### Calculating Field strength of a air core solenoid

I want to build a magnetizer for charging / magnetizing small alnico magnets for that I am thinking to discharge a cap into a air core solenoid. The magnet to be charged would be kept within this ...
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### Forensics: electrostatic detection circuit for lifting “indentations” from documents

Wikipedia explains that an EDD: ...is a specialized piece of equipment [used to] reveal indentations or impressions in paper which may otherwise go unnoticed. The electro-physical basis whereby ...
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### Question about electric fields [duplicate]

Ok so I have this question: Two point charges of charge -2 µC and -3 µC respectively are separated by a distance of 15 cm. Point X is positioned at an equal distance away from each of the charges. <...
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I am just very confsed about how to do these sort of questions where they give you a point in the middle of two charges. The farthest I've gotten in questions relating to coulomb's law, is using the ...
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### Dispersal of radio energy as it moves further away from the source

I apologise for the wording of my question, it will no doubt come across as confusing. If there is anything you are unsure about please feel free to ask me. Question As a radio wave moves further ...
### $2n$ point charges on a circle at $O$, what's total electric field intensity $\overline{E}$ at $\pm 1\mathrm{m}$?
The problem reads is from a Schaum's Outlines of EMFT and reads: A total charge of $1\mathrm{nC}$ is equally distributed among $2n$ points which are placed equidistantly on a circle with \\$1\...