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. A

    How do you Find Gravitation Field strength

    Homework Statement what is the gravitational field strength on the surface of a star that has a radius of 5.0 x 10^6km and a mass of 6.0 x 10^33 kg Homework Equations i tried the F=G MM/r^2 The Attempt at a Solution answer was rly weird and off
  2. T

    Magnetic Field Strength of an Electromagnet given variable currents

    I had a lab to do for Physics, and we used a variable voltage source and an electromagnet with 60 turns of copper wire. What is the equation to use to find the magnetic field strength B using relative permeability of a soft iron core? i cannot find this equation anywhere... plus, what is the...
  3. S

    Gravitational field strength problem- help needed

    gravitational field strength problem-urgent help needed Homework Statement Moon has a radius of 1740km, Mass of 7.35 x10^ 22kg, grav field strength of moon= 1.62Nkg^-1, distance from Earth to Moon is 380000km G=6.67x10^-11Nm^2kg^-2 The Moon's gravitational pull on the Earth causes the...
  4. L

    Electromagnetic field strength tensor- Magnetic monopoles

    Hey! I stumbled across this problem while reading Wald's "General Relativity", but it belongs to Electrodynamics. In problem 3 of chapter 6 one has to find the general form of a static, spherically symmetric Maxwell tensor, which is clearly F_{ab}=A(r)(dt)_a \wedge (dr)_b+B(r)r(d\theta)_a...
  5. B

    Magnetic field strength dependent on distance from source

    I am trying to find an equation that tells the strength of a magnetic field a given distance away from the source. It would be very helpful if all terms are defined, since the internet is notorious for not saying what variables mean. Gracias
  6. I

    What is the magnetic field strength?

    Homework Statement A 14.2 cm - diameter circular loop of wire is placed with the plane of the loop parallel to the uniform magnetic field between the pole pieces of a large magnet. When 3.10 A flows in the coil, the torque on it is 0.135 m N. What is the magnetic field strength? 2...
  7. A

    Testing the field strength of a permanent bar magnet

    Hi, I've just completed a prac, where a beam was placed into a solenoid with a current flowing through it, causing a force to exerted down and I balanced out the force by placing weights on the other end in the effort of calculating the magnetic field strength. Anyway, one of the short answer...
  8. J

    Magnetic Field Strength and Webers

    OK well, this isn't a question as such, more a conceptual thing... The formula, B=(Weber)/(Area) gives the magnetic field strength, B in Tesla... . But when I rearrange in terms of magnetic flux, it's obviously (Tesla) X (Area). My question is, how is the flux (lines of force) defined by the...
  9. jfy4

    Is the Lagrangian for LQG similar to that of Yang-Mills theories?

    Hi, There is clearly an analogous relationship between Yang-Mills theories and LQG, for example the covariant derivative, the field strength tensor, the field and its conjugate momentum etc... I am wondering how far this analogy extends. Specifically, is the Lagrangian for LQG the...
  10. M

    Engineering Induction Motors, Generators, Magnetic Field Strength, Force and Coupling

    Homework Statement Here are a bunch of questions that I've attempted. I feel fairly confident with my answers, but I just wanted to make sure :) Thanks! a) calculate the synchronous speed, amount of slip and the percentage slip in a typical aircraft a.c., four pole, 400hz induction motor...
  11. matt_crouch

    Calculate the electric field strength inside and outside a wire

    Homework Statement An infinitly long conducting cylinder of Radius R carries a inform surface charge of (lambda per unit length) determine the electric field strength inside and outside the cylinder Homework Equations integral (E.ds)= q/e0 The Attempt at a Solution im not really sure what...
  12. G

    Is cross-sectional area of a coil related to it magnetic field strength

    I have to desgin an experiment for physics and and my research question is going to be: How does the cross-sectional area of the solenoid’s coil affect the strength of its magnetic field? This is my hypothesis, my question is if you think the reasoning is valid. I believe I should find it is...
  13. A

    Capacitance and max field strength of a concentric sphere capacitor

    Homework Statement A capacitor is formed by two concentric spheres r1= 30 cm and r2=15 cm, with a liquid insulant between them with relative permittivity Er=4. The potential difference between the spheres is 1 kV. Find: 1. capacitance 2. maximum field strength in the gap between the two...
  14. I

    How Does Current in a Semicircular Wire Affect Magnetic Field at a Point?

    Homework Statement A wire in the shape of semicircle with radius a is oriented in the yz-plane with its center of curvature at the origin (Fig. 28.67). If the current in the wire is I, calculate the magnetic-field components produced at point P, a distance x out along the x-axis. (Note: Do not...
  15. M

    Electric Field Strength as a Vector along a line

    When Calculating Electric Field Strength using Q/kr^3, if the Q is negative is this negative disregarded? If not this would make E around a negative charge, negative. But if a positive test charge (q) is placed between two charges (Q1(negative) and Q2(positive)) then for Q1 (the negative charge)...
  16. I

    What is Gravitational field strength exactly

    Hello, I just read a book reagarding Newton and his laws and had few questions about it. What is Gravitational field strength exactly and what is Newton's universal gravitational constant? Aren't they the same thing? please explain these two concepts simple enough for me to understand and to...
  17. T

    Calculating Electric Field Strength for a Point Charge and Proton Interaction

    Homework Statement (This was part of an assignment that we had to create, so the question is one of my own, although I'm not quite comfortable with this area, hence why I'm asking for help) Calculate electric field strength of a positive point charge of 1.3x10-7C that is 5.3x10-4m away from a...
  18. W

    What is the Correct Approach for Calculating Magnetic Field Strength?

    Homework Statement Homework Equations The Attempt at a Solution I let µ be 9, as that's the approximate permittivity of air/ free space. I assumed that as a hat had a subscript y, it ran parallel to the y axis, and worked from there, getting the cross product of the unit...
  19. M

    Understanding Flux Meters and Field Strength Measurement

    How do flux meters work ?? On what basis they measure the strength of field please share the link (Urgently required)
  20. L

    Limitations/Weaknesses of Magnetic field strength Lab

    Homework Statement So I have done a lab involving how Magnetic Field Strength varies with distance from a magnet. using a magnetic field sensor, some recording software, a meter stick a magnet. From this I gathered the fact that as distance increases magnetic field strength decreases...
  21. X

    Practical field strength leads to negligible term ?

    Homework Statement the Hamiltonian of a free particle in an electromagnetic field is, H=H_{free} + H_{int} + \frac{q^2 A^2}{2mc^2} where the free Hamiltonian is just {p^2}/{2m} and the interaction Hamiltonian is, H_{int} (x) = -\frac{q}{mc}p\cdot A + q A_0 Show that the last term in...
  22. M

    Calculate Magnetic Field Strength for Deflecting Electron in CRT?

    Homework Statement An electron in a cathode-ray tube is accelerated through a potential difference of 10kV, then passes through the 2.0cm wide region of uniform magnetic field.What field strength will deflect the electron by 10 degrees? Homework Equations Ki + Ui = Kf + Uf K =...
  23. C

    Electric Field Strength Inside a Cylindrical Non-conductor

    Homework Statement Hey everyone, I'm just studying some physics, and came across this question where I don't know why I'm wrong =( It's from Physics (5th Ed.) by Halliday, Resnick and Krane - Chapter 27, Exercise 22 Positive charge is distributed uniformly throughout a long, nonconducting...
  24. S

    Difference between Electric flux density,electric field strength .

    Difference between Electric flux density,electric field strength... I want to know the difference between,electric flux density and electric field strength.Are they the same? And also,there is a magnetic field(measured in Tesla),magnetic flux(in Weber),magnetic flux density(Weber per...
  25. D

    Current and electric field strength question

    Homework Statement A wire carries a current and consists of three sections with different radii. Rank the sections according to the following quantities, greatest first: (a) current, (b) magnitude of current density, and (c) magnitude of electric field. Homework Equations i =...
  26. M

    Projectile motion and electric field strength

    Homework Statement An electron is launched at a α=38.5° angle and speed of 4.12×10^6 m/s from the positive plate of the parallel plate capacitor shown. If the electron lands d=3.03 cm away, what is the electric field strength inside the capacitor? Homework Equations t = d/v v0y =...
  27. R

    Coaxial cable problem, electric field strength?

    Homework Statement A coaxial cable has an inner core diameter 6mm and inner diameter of the outer sheath is 20mm. There are two layers of insulation between the conductors, the inner layer from a radius of 3mm to 9mm has relative permittivity of 8 while the outer layer from radius 9mm to...
  28. D

    Gravitational Field Strength and Acceleration on Mars

    How are the numerical values of gravitational field strength and acceleration due to gravity on Mars related?
  29. M

    Magnetic Field Strength: Inverse Proportionality to Square or Cube?

    I have read a number of journal article that state that magnetic field strength diminishes inversely proportional to the square of the distance. BUT more than one has stated that the field strength is inversely proportional to the cube of the distance from the surface of the magnet. Which one...
  30. H

    It is asking for the magnitude and direction of the electric field strength

    What are the magnitude and direction of the electric field strength at point Z in the following: Point X, q1 = -2.0 x 10^-5 and it is 60 cm to the left of point Y, q2 = 8.0 x 10^-6, which is 30 cm to the left of Z. Essentially, this is what it looks like: X-------Y--Z
  31. T

    Can gravitational field strength equal the centripetal acceleration?

    As a homework question, it asks, "...if the Earth were rotating so fast that the objects at the equator were apparently weightless?" Somewhere, someone said that, quote: In order for the rotation of the Earth to cancel weight, the gravitational field strength should equal the centripetal...
  32. M

    FODO cell, find the field strength of a quadrupole.

    Homework Statement A quadrupole doublet, otherwise known as a FODO cell, is made of two thin quads f1 = -f2 = 5m, and the distance between the magnets is, d = 1m. The length of both of the quadrupoles is 0.2m, and I have to calculate their field strengths. Homework Equations Field...
  33. N

    Irradiance and electric field strength

    Dear physicists, I am desperate. I am using a QM code to propagate a wavefunction of a system that experienced an electric field pulse. However, in literature all values for the electric field strength are given in V/m but the program asks for W/cm^2! I am kind of very confused here and did not...
  34. T

    How Do You Calculate Gravitational Field Strength Between Two Planets?

    Homework Statement Write an expression for the gravitational field strength E at a point distance r from a planet of mass M. (In my diagram, there are two planets with mass, m and distance 2a apart) Homework Equations The Attempt at a Solution The resultant gravitational field...
  35. J

    Measuring Tiny changes in Electric Field Strength

    Hi all I am looking to measure minute changes in electric field strength. I found this article http://www.physorg.com/news74876394.html" which describes how scientists at harvard isolated a single electron in a highly evacuated, absolute zero chilled chamber and manipulated its movement using...
  36. R

    Calculate electric field strength from voltage?

    Hi, I am trying to work out the electric field strength associated with a number of different electronic systems at a given distance. I am able to simplify the systems so that I only need worry about the fields from a high-voltage busbar or cable. I know that electric field strength from a...
  37. G

    Calculating magnetic field strength (complex)

    okay guys, i think I am out of my depth on this problem. Im doing a long investigation on eddy currents, and i derived a formula. I am reaching the end of the investigation, and so i wanted to compare my experimental data to expected data. One of the factors i was investigating is the...
  38. D

    Magnetic field strength - unit conversions

    I have to spec a sensor to monitor the magnetic field of a DC solenoid element. The specification for the solenoid includes its length, DC resistance, current at the applied supply voltage, and most importantly, the expected Dipole Moment of the unit, as 42 Am^2. I plan to attach a solid...
  39. Q

    Variation of gravitation field strength?

    Hi all, this will be my first physics qns:D more to come... I just learned that value of g at the equator is not exactly equal to the gravitational field strength. Can anyone explain with workings? i don't really understand my teacher workings. Also can i clarify if -We're assuming Earth...
  40. M

    Electric field strength at the midpoint between the two charges.

    Homework Statement A + 7.3 nC point charge and a - 2.4 nC point charge are 3.5 cm apart. What is the electric field strength at the midpoint between the two charges? Homework Equations E = 9*10^9(q/r^2) q = charge r = distance from point charge The Attempt at a Solution Since...
  41. J

    Ampere's Law: Calculating Magnetic Field Strength

    Homework Statement Homework Equations State Amperes Law. Show that the magnetic field at a distance R from a very long straight wire carrying a current I has magnitude μ I / (2 pi R) The Attempt at a Solution I really don't know :(
  42. F

    Magnetic Field Strength at a Point Along an Infinite Wire

    Homework Statement A current I flows to the right on the x-axis from the origin to x = infinity. What's the magnitude of the magnetic field at (x,y) = (0,L)? Homework Equations B = u sub 0 time I/(2 pi R) The Attempt at a Solution We use above equation since we have an extremely...
  43. S

    Magnetic Field Strength Needed

    Homework Statement Hi, I am trying to calculate the current and magnetic field strength needed to pick up a 0.3125 lb. piece of a channel lock plier made of ferritic stainless steel (they have a soft magnetic component) on its y-axis (on the lighter part of the piece) at an 80 degree angle...
  44. X

    Gravitational field strength unit

    What quantity has the same numerical value as the gravitational field strength, but is expressed in a different unit? g= 9.8 N/kg i can't think of anything else that's 9.8 besides g
  45. M

    Field strength between two wires

    I feel like a stupied girl. :( It think it's not very hard, but I have to have the correct answear before i send it to my school. Homework Statement We sometimes exposed to electric fields. To determine whether there is a risk of flashover is a rule of thumb which states that the sparks will...
  46. K

    To investigate a factor affecting the magnetic field strength of a magnet

    1. As mentioned in the title,we were asked to investigate a factor that affects the magnetic strength of a solenoid. Independant variable is current.I used a solenoid , put it on a stand vertically,above of a magnet placed on a digitall weighing machine.I set the solenoid,a device to measure...
  47. I

    Dual field strength equals to itself

    \epsilon^{\mu_1\mu_2\cdots\mu_k\ \mu_{k+1}\cdots\mu_D} \epsilon_{\mu_1\cdots\mu_k\ \nu_{k+1}\cdots\nu_{D}} = (-1)k!\delta^{\mu_{k+1}}_{[\nu_{k+1}}\cdots\delta^{\mu_D}_{\nu_D]}\quad\cdots(*) where we are working in the Minkowski space. And the definition of square bracket on indices is like...
  48. Z

    Find the Electric Field strength

    Homework Statement "A copper cable carrying 50A current has radius 0.003m. What is the electric field if copper has a resistivity of 1.7x10^-8 Ohm/m?" Homework Equations Formula for current density etc. The Attempt at a Solution So I write: \vec{\mathbf{J}} = n|q|v_d = \frac{I}{A}...
  49. J

    Electric Field strength of sphere

    Hi everyone I just need some help with this question. Its a simple one I'm pretty sure. Homework Statement A solid sphere of radius 3 cm is made from a conductor and has a charge of + 4 uC placed upon it. What is the electric field strength 1 mm from the centre of the sphere? Homework...
  50. J

    Need help understanding off axis electromagnet field strength equation

    I have this equation for the magnetic field strength of an electromagnet but it’s in the form of multiple polynomials. Here is the page where they all are: http://www.netdenizen.com/emagnet/offaxis/solenoidoffaxis.htm since it gives values for e_8 and p_8 I tried using the main equation up...
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