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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1answer
51 views

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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37 views

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 ...
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1answer
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-...
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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 ...
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1answer
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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1answer
143 views

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 ...
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3answers
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 ...
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1answer
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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1answer
35 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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1answer
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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4answers
818 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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0answers
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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1answer
84 views

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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2answers
94 views

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 ...
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1answer
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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2answers
95 views

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 $$\vec{E_0} = -\vec{e}_y * 10\frac{kV}{cm}$$ ...
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2answers
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 ...
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2answers
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. ...
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1answer
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 ...
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0answers
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 ...
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0answers
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, ...
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2answers
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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1answer
53 views

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 ...
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1answer
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 ...
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2answers
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 ...
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1answer
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 ...
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1answer
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 ...
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1answer
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 ...
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3answers
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 ...
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1answer
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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1answer
77 views

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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1answer
278 views

Fetch RSS value using Nordic NRF24L01 module and RadioHead library

RadioHead provides a lastRssi() function (http://www.airspayce.com/mikem/arduino/RadioHead/classRHGenericDriver.html#ab04f2ca335d89f5fac1d213c0aea9da2) to fetch the ...
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1answer
52 views

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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1answer
114 views

Question about Coulomb's law

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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2answers
84 views

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 ...
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1answer
78 views

\$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\...
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2answers
7k views

how much voltage pass through antenna? [closed]

I want to know how much maximum voltage can be generated on a receiving antenna. Also, please help me to find an antenna design with maximum received signal voltage; I dont have proper knowledge of ...