What is Field strength: Definition and 367 Discussions

In physics, field strength means the magnitude of a vector-valued field (e.g., in volts per meter, V/m, for an electric field E).
For example, an electromagnetic field results in both electric field strength and magnetic field strength.
As an application, in radio frequency telecommunications, the signal strength excites a receiving antenna and thereby induces a voltage at a specific frequency and polarization in order to provide an input signal to a radio receiver. Field strength meters are used for such applications as cellular, broadcasting, wi-fi and a wide variety of other radio-related applications.

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  1. Ramtin123

    A Non-Abelian Kinetic Mixing

    Consider two non-Abelian gauge fields ##A_\mu^a## and ##A_\mu^{'a}## belonging to the same symmetry group. An example could be the SM electroweak isospin fields and another exotic SU(2) hidden sector where ##a=1, \dots 3##. Is the kinetic mixing of the following form gauge-invariant? $$...
  2. I

    I Exploring Field Strength & Singularities

    Why doesn't this work if the field is strong? Or does it work as long as there are no singularities? Mentor's Note: Original thread title was, "Calculating rest mass by integrating T_{00} over a 3 volume for static metric"
  3. M

    A Maxwell theory invariant under dual field strength tensor application

    Hello everybody! I know in classical field theory adding in the Lagrangian density a term of the form Fαβ (*F)αβ (where by * we denote the dual of the field strength tensor) does not change the EOM, since this corresponds to adding a total derivative term to the action. However when computing...
  4. Barbequeman

    Calculating Velocity & Field Strength of Gas: Help Needed!

    For the first calculation of the velocity of the gas I use the first equation and this converted in meter would be look like this (first value as an example) v=299792458 m/s * (6.76813x10^-7-6.768x10^-7)/6.768x10^-7 =5836.03m/s or 0.0019c this was the velocity of the gas for the first spectral...
  5. X

    I Magnetic field strength of a stack of magnets

    I know that for a single cylindrical neodymium magnet, the formula $$ \displaystyle{\displaylines{B(z)=\frac{μ_0M}{2}(\frac{z}{\sqrt{z^{2}+R^{2}}}-\frac{z-L}{\sqrt{(z-L)^{2}-R^{2}}})}} $$ shows the relationship between the magnetic field strength and the distance between the magnet. I was...
  6. Tesla In Person

    Electric field strength at a point due to 3 charges

    I got E. 13q as the answer. That is what i did: The electric field due to +q at origin 0 should equal the electric fields of charges -3q and the new charge placed at 2x. So applying the equation above like this; k*(q) / (2^2) = -3q*k + (k*C)/ 4 solving for C the new charge added, gives 13q. I...
  7. K

    I Postulating a minimum gravitational field strength

    this paper postulating a minimum gravitational field strength postulating a minimum gravitational field strength (minimum curvature) and a minimum acceleration but otherwise leaving Gr could reproduce MOND [Submitted on 25 May 2022] MONG: An extension to galaxy...
  8. R

    I Relation between electric & magnetic fields in terms of field strength

    Hi. A electromagnetic wave consists of an electric and a magnetic component. I believe that the electric field strength is measured in volts per meter. The magnetic field I think is measured in Tesla. Let's imagine that I measure the electic field strength of two different radio stations and...
  9. P

    I What's the field strength and pattern rules for bar magnets attached?

    The attached probem tricked me because the answer is apparently D and not A. Presumably because the magnetic field is weaker with 2 bar magnets joined N/S compared to a single bar magnet. So this seems to be a gap in my knowledge as to the resulting strengths of magnets joined together. Are...
  10. wnvl2

    I Rindler Transformation & 't Hooft's Introduction to General Relativity

    I am reading 't Hooft introduction to general relativity. https://webspace.science.uu.nl/~hooft10 ... l_2010.pdf In this text 't Hoof derives the Rindler transformation. A little bit further he writes My question is, how does he come to that formula $$\rho^{-2}g(\zeta)$$
  11. Einstein44

    I Calculating Magnetic field strength of a magnet

    I have been trying to calculate the magnetic flux thought a single loop of wire occurring from a magnet (meaning it has a nonuniform field), so I have the following equation: Φ=∮BdAcosθ Now my problem is that I do not know how to calculate the magnetic field strength (B)of that magnet (which...
  12. VictorMedvil

    A What Superconductor Can Have The Highest Magnetic Field Strength?

    Hello, I asked a question about superconductors in 2020 and I was now wondering what superconducting chemical/material can have the highest magnetic field strength before the superconductivity is destroyed by it? Secondly, What the is maximum magnetic field strength of said material in Tesla per...
  13. E

    Find the gravitational field strength of planet X

    weight/mass = gravitational field strength. my working is -> weight = 150kgx10m/s² = 1500N mass = 150kg gravitational field strength= 10N/kg. is this correct?
  14. J

    How to find an expected value for magnetic field strength?

    Our class modified an experiment to measure the magnetic field strength in mT between 5cm and 30cm, and I have plotted data and found that the relationship resembles a power relationship (using a log vs log graph). In order to find the percentage uncertainty for the whole experiment I need the...
  15. Y

    How does the saturation flux density affect magnetic field strength?

    So I'm confused what the Saturation Flux Density is referring to. Defintion says it is when you no longer get an increase in H-field when increasing external B-field. So, does the satuation flux mean the core can only create fields UP TO that saturation flux, or that it can make a stronger...
  16. P

    Engineering Magnetic field strength of an electromagnet (coil wound around a bobbin)

    I am trying to design an electromagnet which consists of a copper PVC sheathed wire wound around a cylindrical plastic spool of Circumference (C) = pi x diameter. The spool has a hollow body of diameter D1. This wire has maximum length (L), cross sectional area A, resistivity P. The spool once...
  17. DuckAmuck

    I EM Field Strength in Curved Spacetime: Is it Unchanged?

    It seems a gravitational field does not alter the electromagnetic field strength. Is this correct? My reasoning: With no gravity, field strength is: F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu Introduce gravity: \partial_\mu A_\nu \rightarrow \nabla_\mu A_\nu = \partial_\mu A_\nu +...
  18. AN630078

    Gravitational Field Strength at the equator and poles

    1. The centripetal force is equal to F= mv^2/r. The velocity of the Earth can be found by: V=2πr/T T=1 day = 24 hr*60min*60sec=86400 s v=2π*6.4 x 10^6/86400 s v=465.4211 ... ~465 ms^-1 to 3.s.f Therefore, F=1*465/6.4 x 10^6 F=98/1280000=7.265626 *10^-5 ~7.3 *10^-5 N Would this be correct since...
  19. E

    B Change in field strength if two variables are incremented at the same time

    Given the example g = \frac{GM}{R^{2}}, we may compute the change in field strength if the mass is changed by a small amount dM to be$$dg = \frac{G dM}{R^{2}}$$and also if R is changed by dR,$$dg = \frac{-2 GM dR}{R^{3}}$$If, however, both the mass and radius are changed by a small amount at the...
  20. P

    Measuring Magnetic Field Strength of a Cylindrical Magnet

    Hello, Today I am wondering if anyone can help me quantify the strength of the magnetic field created by a permanent cylindrical magnet. I have been able to find equations online for the strength of the field within the z axis, (ie. the longitudinal length) but I would like to know the strength...
  21. R

    Derivation of ideal magnetic dipole field strength

    For reference, this is from Griffiths, introduction to quantum mechanics electrodynamics, p253-255 When deriving the ideal magnetic dipole field strength, if we put the moment m at origin and make it parallel to the z-axis, the book went from the vector potential A $$ A=...
  22. O

    A Verifying the Relation in Yang-Mills Theory with a Scalar Field

    I'm trying yo verify the relation \begin{equation} [D_{\mu},D_{\nu}]\Phi=F_{\mu\nu}\Phi, \end{equation} where the scalar field is valued in the lie algebra of a Yang-Mills theory. Here, \begin{equation} D_{\mu}=\partial_{\mu} + [A_{\mu},\Phi], \end{equation} and \begin{equation}...
  23. N

    Finding the Earth's magnetic field strength using a Galvanometer

    Homework Statement [/B] I am working on a experiment on finding the Earth's magnetic field strength in Denmark. Using a Galvanometer and a constant power source of 5.1V and slowly adjusting the resistance, I was able to find the changes in angle in relation to the changes of current. 2...
  24. G

    B Coil B field strength with different diameters

    Hi, I have a quick question. Say I have two metal rods or tubes and I want to make an electromagnet, one rod is with a diameter x and the other rod has a diameter of x2 (two times larger) Now I take the same gauge copper wire and wrap an equal amount of turns around each of the two rods. Then I...
  25. S

    I Time Dilation: Does Gravitational Field Strength Matter?

    Hi I have 2 questions. There are 2 planets and one clock on each of them. One of them has a bigger gravitational field strength. And two clock have same distance from the core. 1-) Does time dilation occur between two? Which clock ticks slower? 2-) If time dilation occurs, which formula...
  26. V

    A How are curvature and field strength exactly the same?

    I am watching these lecture series by Fredric Schuller. [Curvature and torsion on principal bundles - Lec 24 - Frederic Schuller][1] @minute 34:00 In this part he discusses the Lie algebra valued one and two forms on the principal bundle that are pulled back to the base manifold. He shows...
  27. BookWei

    Field strength tensor for a moving charged particle

    Hi, I am studying Chapter14 in Jackson. My attached file is about field strength tensor. My question is how can I obtain the radiation and the non-radiation terms in the field strength tensor for a moving charged particle. Many thanks.
  28. Juan Andrew

    Calculating Magnetic Field Strength in a Stator DC Motor

    Hey, I need a little help I know in a DC motor there are permanent magnet and also coil So my question is, what is the equation to calculate the magnetic field strength in a stator dc motor compound?
  29. radiant_june

    Electric field strength at a point between charges

    Find the electric field strength at point B between two charges shown below: Given/Known Values q1 = 4.0×10-6 C r1 = 40 cm = 0.4 m (Distance from q1 to point B) q2 = -1.0×10-6 C r2 = 30 cm = 0.3 m (Distance from q2 to point B) k = 9.0×109 Nm2/C2 Equations Electric Force: FE = (k⋅q1⋅q2)/r2...
  30. N

    Magnetic field strength at a distance

    Hopefully, a simple question with a simple answer. I have a flat magnet (assume infinite long and wide) with a field strength at the surface of (for simplicity) exactly 1Tesla. What will the field strength be (in air) 1mm away from that surface? I know approximates to 1/r^3, but 1/0.001^3 =...
  31. starstruck_

    Calculating electric field strength

    Homework Statement A cylinder of radius R= cm 1.2 and length L= 51 cm has a charge Q=2.3 μC spread uniformly along its surface (and not on its flat ends). a) Calculate the electric field strength a distance d=4 mm from the cylinder’s surface (not near either end) b)Calculate the electric...
  32. M

    I Will a solenoid inside another solenoid increase its strength?

    Will placing a solenoid inside another solenoid increase it's over all strength? While doing research into solenoids I came across the MagLab (The National High Magnetic Field Laboratory) where they place coils one inside another to bolster the field, and reach upwards of 45 Tesla. They use an...
  33. C

    Electric field strength between charged plates help

    Homework Statement Homework EquationsThe Attempt at a Solution E=kq/d2 how do I involve the kinetic energy K in the equation?
  34. C

    Electric field strength between charged plates

    Homework Statement Homework EquationsThe Attempt at a Solution E=kq/r2 so when the distance increase E should decrease? I know this is wrong, but can someone explain why? Thanks
  35. C

    Electric field strength

    Homework Statement Homework EquationsThe Attempt at a Solution I tried to use the formula: F=kq1q2/r2 So at point B, the electric field strength is( 2kQ/r2) - (-kQ/r2)= 3kQ/r2 At A: (2kQ/r2)+(-kQ/r2)=kQ/r2 At C: -(2kQ/r2)-(-kQ/r2)=-kQ/r2 So B is the strongest? Is there an easier way to do it?
  36. C

    Magnetic Field Strength

    Homework Statement Homework EquationsThe Attempt at a Solution Shouldn't they be the same? Does one being above the current and the other being below make any difference? I know when there is a higher density of magnetic field lines, the magnetic field strength is greater, but in this case...
  37. chopnhack

    Electric field strength on particles of various distances

    There is no math in this one! I just wanted to know if I had the idea correct. Homework Statement If I have two positively charged particles at a distance between them that a field is produced between and around them, will test particles that repel away be solely a function of their distance...
  38. hilbert2

    A Field strength measurement and continuity

    Something about the theory of quantum measurement/collapse in the case of quantum fields... Suppose I have a field, either a scalar, vector or spinor, that I want to describe as a quantum object. For simplicity let's say that it's a scalar field ##\phi (\mathbf{x})##, where the ##\mathbf{x}## is...
  39. psy

    Calculation of the electric field strength

    Hey, First I want to find the electric field strength from the middle between two point charges q1 = 8nC and q2 = -6nC. The distance between the two charges is 10 cm. Then i want to find out at which point of a straight line, which runs through the two charges is the electric field strength...
  40. David23454

    Field strength to deflect electron in a cathode-ray tube

    Homework Statement An electron in a cathode-ray tube is accelerated through a potential difference of 10 kV, then passes through the d = 2.4-cm-wide region of uniform magnetic field in the figure(Figure 1) . What field strength will deflect the electron by θ = 13 degrees?Homework Equations...
  41. M

    Calculating Magnetic Field Strength from FFT

    Hello All, Briefly on the exposition; I'm an undergraduate assistant to a professor. We contribute to the Muon g-2 experiment in Fermilab, designing and optimizing the magnetic-measurement equipment. As you might imagine I utilize the Fourier Transform often to analyze data. The data I'm...
  42. F

    Electric field strength inside a conductor

    I read on physics.stackexchange that using Gauss Law we can prove that the electric field strength increases as the radius increases inside a metallic conductor. Later on the same website, I encountered a contradicting statement that claimed that inside a conductor, the charges aren't free to...
  43. S

    A Proof - gauge transformation of yang mills field strength

    In Yang-Mills theory, the gauge transformations $$\psi \to (1 \pm i\theta^{a}T^{a}_{\bf R})\psi$$ and $$A^{a}_{\mu} \to A_{\mu}^{a} \pm \partial_{\mu}\theta^{a} \pm f^{abc}A_{\mu}^{b}\theta^{c}$$ induce the gauge transformation$$F_{\mu\nu}^{a} \to F_{\mu\nu}^{a} -...
  44. Luca_Mantani

    A LSZ formula and Field Strength renormalization factor

    Hi all, I have doubts on the role of the Field Strength renormalization ##Z_\psi=1+\delta_\psi## when computing amplitudes. I never did this, maybe because it was not needed before, but i noticed that in the solution of a specific problem, to obtain the correct result, you need to multiply the...
  45. P

    Electric field strength in an ink-jet printer

    Homework Statement One type of ink-jet printer, called an electrostatic ink-jet printer, forms the letters by using deflecting electrodes to steer charged ink drops up and down vertically as the ink jet sweeps horizontally across the page. The ink jet forms 29.0 μm diameter drops of ink...
  46. M

    Difference Electric Field Strength Point Charges vs. Plates

    Why does the electric field strength on a straight line (E = k.(Q1/d12+Q2/d22). D1,2 = distance with respect to Q1,Q2) between two point charges vary with the location on this line while the field strength between two parallel plates which remains the same anywhere between the plates...
  47. Iron_Man_123

    Electric field strength -- calculating distance from charge

    Homework Statement At a distance D from a very long (essentially infinite) uniform line of charge, the electric field strength is 1000 N/C. At what distance from the line will the field strength to be 4000 N/C? Homework Equations E=kq/r2 The Attempt at a Solution I know that E is inversely...
  48. ReidMerrill

    Ligand Field Strength and UV absorbance

    I have a lab report for an experiment in which we used ion exchange chromatography to separate three Chromium complexes, CrCl2(OH2)4+, CrCl(OH2)52+, and Cr(OH2)63+ We used a UV vis to find the absorbance of each compound and used that to calculate the mole fraction of each ion in a mixture. One...
  49. M

    Relationship between emf and magnetic field strength

    Homework Statement See image below. Homework Equations motional emf = induced voltage = B L v The Attempt at a Solution I thought the answer would be A since there's a direct relationship between EMF and magnetic field strength. The answer is D.
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