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. C

    Gauge transformation of Yang-Mills field strength

    Hi. I'm reading about non-abelian theories and have thus far an understanding that a gauge invariant Lagrangian is something to strive for. I previously thought that the Yang-Mills gauge boson free field term ##-1/4 F^2 ## was gauge invariant, but now after realizing that the field strength...
  2. W

    Magnetic field strength infinitely long wire

    I'm new to posting on this forum so excuse me if I'm using the wrong symbols underlined := vector/vectorfield δ := derivative uvar := unit vector Homework Statement Consider a finitely conducting wire of infinity length with radius b. The wire is centered about the z-axis. Current is...
  3. I

    Gravitational field strength of 0

    Homework Statement A planet of mass 1.88x10^21 kg has a moon of mass 4.56^10^19 kg. The distance between their centers is 3.94x10^8 m. How far from the center of the planet (along the line joining the planet and the moon) is the net gravitational field strength, due to the two bodies, equal to...
  4. K

    Calculating the Field strength of a magnet at a certain distance

    Is there a way to calculate the magnetic field strength, B, of a magnet (permanent magnet, not an electromagnet) at a certain distance? I assume it follows the inverse square law, but other than that, I do not know what to do. Tools I have available: permanent magnet ammeter/voltmeter...
  5. D

    Gravitation equations and expressions - gravitational field strength

    Homework Statement i have 2 questions on my holiday homework that I am not 100% sure on they are: Homework Equations 1) write down an algebraic expression for g at a distance r from the centre of the planet. The planet can be treated as a point mass of magnitude M as its centre AND 2) write...
  6. E

    Do I have to re-define electric field strength in Centre of Mass frame

    So let's say I'm computing the torque as a result of the interaction between two electric dipoles in the lab frame. Let's imagine they are in some electric field. I then do : τ = r×F If I now switch to the centre of mass frame I have to find their position vectors from the COM. Why do...
  7. R

    Find the Electric field strength at a point between two charges

    Homework Statement See images Homework Equations See images The Attempt at a Solution I have tried parts C and D several times, and the homework program is telling me that it's still not correct. For C, I keep getting: 7.7x10^8 N/C for D I keep getting: 7.1x10^-12 N/C...
  8. T

    Help Experiment determining the Earth's magnetic field strength

    I am in my senior year of school and I have been given a research task to do on the Earth's magnetic field in a given place. I have to come up with a full method for the experiment to perform in class in a week or so and then I need to use equations to create a discussion and show how I found...
  9. C

    Calculating electric field strength, potential difference, and force.

    Homework Statement I'm pretty sure I have done questions 1 to 4 correctly, it is just question 5 I am struggling with. I have an exam in one week and this is revision so it will not get marked by a tutor, and it would really help if someone could give my answers a quick check and help me...
  10. R

    Measuring earth magnetic field strength

    I'm somewhere at a suburb near Sydney and I have problems designing an experiment to measure the strength of the Earth magnetic field so that means now I'm close to geographic south and I'm close to magnetic north right? how do I measure the angles between the GS and Mn and what do I have to...
  11. H

    Gravitational field strength (ratios)

    Homework Statement A 6.2*10^2-kg satellite above Earth's surface experiences a gravitational field strength of magnitude 4.5-N/kg. Knowing the gravitational field strength at Earth's surface and Earth's radius, how far above Earth's surface is the satellite? (Use ratio and proportion.)...
  12. R

    Electric Force and Field Strength Problem

    Three charges are located on a coordinate plane scaled off in meters. Charge #1 is 5 nC and located at (0,0). Charge #2 is -3.0 nC and located at (0,-.10). Charge #3 is 6.0 nC and is located at (-3,0). a) What is the net force (magnitude and direction) on the charge at the origin? b) What is...
  13. J

    Find electric field strength between disks

    Homework Statement Two 2.0cm diameter disks face each other, 1.0mm apart. They are charged to -10nC and 10nC. -What is the field strength between the disks? -A proton is shot from the negative disk toward the positive disk. What launch speed must the proton have to just barely reach...
  14. C

    Gravitational field strength between masses

    Homework Statement A mass at a point X gives rise to a gravitational field strength g at point P as shown. An identical mass is placed at point Y x ________ p ______________________ y The resultant g f s is now? Homework Equations g = Gm/r2 The Attempt at a Solution...
  15. W

    Calculating Magnetic Field Strength in a Balanced System

    Homework Statement Homework Equations force = current * length * field strength * sin (theta) current = 5.6 A mass/ length = 80g/m right angles = sin(90) = 1 The Attempt at a Solution i noticed the mass is given in grams, 80 grams to be exact or .08 kg . how would I find the...
  16. W

    Find magnetic field strength and maximum force

    Homework Statement Homework Equations Force = Current * Length * Field Strength * sin(theta) (Force/ Length)/(Current * sin theta) = Field Strength The Attempt at a Solution (.28 N/m)/ (14 A * sin 27 degree) = .044 T or 44mT
  17. snoopies622

    The uncertainty principle and electric field strength

    As my knowledge of an electric field strength becomes more precise, what physical quantity becomes correspondingly less precisely known?
  18. R

    Electric Field Strength at Center of Triangle

    Homework Statement Three positive charges, A, B and C, of 3 × 10-6, 2 × 10-6, and 3 × 10-6 Coulombs respectively, are located at the corners of an equilateral triangle of side 0.2 meters. Find the magnitude in Newtons/Coulomb of the electric field at the center of the triangle...
  19. F

    Calculate Gravitational Field Strength

    Homework Statement Given Radius is 4.76*10^5 m Astronaut drops a hammer of 0.85kg from a height of 1.25m. It takes 3s to reach the ground What is the gravitational field strength? Homework Equations The Attempt at a Solution g=a=Δv/t v=d/t v=1.25/3 a=1.25/3/3 But that's...
  20. A

    Electric field strength and potential in a charged conducting sphere

    The electric field strength inside a conducting charged sphere is zero, but why? In the book it says "that the field lines would link charges of opposite sign in the sphere and such a state of affairs is impossible under static conditions in a conductor." I don't really get this sentence. And...
  21. U

    Need help with Gravitational Field Strength question

    Homework Statement A satellite orbites Earth at a distance of 3rEARTH, above Earth's surface. What is the magnitude of gravitational field strength at the point where the satellite is?Homework Equations Fg= Gm1m2/d^2 (m1=mass 1, m2=mass2) F1/F2 = D2^2/D2^2 (D1 is a variable, and so is D2, so...
  22. A

    Gravitational field strength of the earth

    Hi, Using the formula g = \frac{GM}{r2} I found 'g' to equal (9.792121683 x 106 \frac{N}{kg}) The value of g is 9.8 \frac{N}{kg}. I am wondering if I made an error in my calculations or if there is a method of simplifying to get 9.8. Thanks,
  23. M

    Why do different gauss meters measure magnetic field strength differently

    I have used two different Gauss meters to measure the same NdFeB rare Earth N45 (45 MGOe) disc magnet (D28X6mm), with a Residual Induction (Br) of 1320-1380 mT. The first is a Dr. Steingroever GmbH FH51 Gauss meter. It would take readings of up to approximately 1.2 Tesla (12,000 Gauss)...
  24. D

    Gravitational field strength for irregular object

    Hi all I'm trying to work out what the surface gravitational field strength of an irregularly shaped body would be (for example Mars' moon Phobos). I know that for a sphere, any point outside it can consider all the mass to be at a point inside it, but for something that's potato shaped, how...
  25. C

    Resultant gravitational field strength

    Homework Statement Consider the objects X and Y, each of mass 8000kg and 2000m apart where XYP forms an equilateral triangle. Determine the resultant gravitational field strength at point P due to objects X and Y. Homework Equations G= GM/R^2 The Attempt at a Solution
  26. D

    Electric field strength between two points.

    Homework Statement Find the electric field strength at point P, which is located midway between charges A and B. The charges are separated by 20 cm. The first charge has a charge of 20 micro coulombs. The second charge has a charge of -30 micro coulombs. Homework Equations Electric...
  27. L

    Solving for Electric Field Strength & Direction of Charged Sphere

    Homework Statement What are the strength and direction of an electric field that will balance the weight of a 1.0g plastic sphere that has been charged t0 -3nC ? Homework Equations E= F/q The Attempt at a Solution Newton's laws on the charged sphere ƩFnet(y) = F -mg=0...
  28. Y

    Gravitational field Strength Inside the Earth

    Since the Gravitational Attractive Force is given by, F_g=(Gm_1 m_2)/r^2 Let m_1be the minor mass of a small body (e.g. human) let m_2 be the massive mass of a huge spherically symmetric body (e.g. Earth) Let r be the...
  29. S

    Free Fall and gravitational field strength

    Hello. For free fall to occur, does the rate at which you fall have to equal the gravitational field strength at that point above the surface? If I'm in an airplane and accelerate towards the ground at an acceleration of 9.8ms^-2 equal to that of the Earth's gravitational field, then I...
  30. P

    Gravitational field strength equals zero?

    There is a point between Earth and moon where the gravitational field strength is zero. What about the same thing with three or more objects? With three of more objects, is there always at least one point where the gravitational field strength due to the objects is zero? Why / Why not?
  31. T

    Electric field strength of van de graff generator

    A VDGG is used to produce a large PD. The dome of the generator has a radios of 0.15m. It is charged and gets a PD between the dome and the Earth of 75kV. The charged stored on it is : 5.0 x 10-6C Answer: Use of E = Q/4∏εr0. 3.0 x 105 My attempt: E = kQ/r2 = 8.99 x 109 x 5.0 x 10-6 /...
  32. W

    Find the current given length and magnetic field strength

    Homework Statement What is the current in a long wire if the magnetic field strength 1.0 cm from the wire's axis is 55 mu T. i know magnetic field strength which is 1 cm i know the length which is 55 milli-tesla. I need to find Current in Amperes which is I. The chapter gives me the...
  33. F

    Electric Field Strength Inside Concentric Uniformly Charged Spheres

    Homework Statement The graph in the figure shows the electric field strength (not the field lines) as a function of distance from the center for a pair of concentric uniformly charged spheres. Which of the following situations could the graph plausibly represent? (There may be more than one...
  34. K

    Where Electric Field Strength + Potential are Zero?

    Homework Statement draw equipotential lines and electric field lines for the following arrangements of charges: a) +4 at (3,5) b) +4 at (3,5) and +4 at (6,5) c) +4 at (3,5) and -4 at (6,5) d) +5 at (3,5) and -2 at (6,5) e) +4 at (3,4), (7,4), and (7,7) f) +4 at (3,4) and (7,4) and -4 at...
  35. E

    Self-Dual Field Strength in complex coordinates

    Hi guys, I have to brush up my knowledge about self-dual Yang Mills and I'm reading an ancient paper by Yang about it...and of course I'm stuck...although Yang writes 'it is easy to see that'... Ok, so the self-duality condition of the YM field strength tensor is defined as...
  36. C

    How to Calculate RMS Magnetic Field Strength from Sunlight Power Density?

    Homework Statement the power density of sunlight, at the earth, is roughly 1 kilowatt/meter^2. How large is the rms magnetic field strength?Homework Equations The Attempt at a Solution I tried using the equation for power density S = E(rms)^2=√(εμ), then substituting B(rms)/c for E(rms), and...
  37. E

    Electric Field Strength and Potential

    Page 10 part (b) (ii) <click on the link Now, the question states : Use Fig. 4.2 to state and explain the distance x at which the rate of change of potential with distance is maximum Now electric field strength = negative potential gradient So in effect they're asking for the point at...
  38. N

    Calculating the field strength of an alternating magnetic field

    I have a solenoid copper coil 7 cm lengths, 5 turns, r =0.75; applied current 145 V; 0.73 A; frequency 1.10 MHz and I'm still not able to calculate the magnetic field strength in kA/m. Can you help me? I tried a number of formulas, but I just don't get it. :confused: Please point me in the...
  39. R

    Electromagnetic field strength

    hello world. it is know that electrostatic (coulomb's law) and magnetostatic (biot-savart law) fields lose their strength like 1/r^2. why do they say that electromagnetic field falls like 1/r ? is that true ? if yes how, can you explain please ? after all energy radiated from a point source must...
  40. C

    Distance away to create the same magnetic field strength?

    1. Homework Statement At what distance (in m) from a very thin, straight wire carrying a 38 A current would the magnetic field strength be the same as a refrigerator magnet of 4.35 x 10-3 T? 2. Homework Equations B=(μo/2pi)*(I/d) where μo=4pi*10^-7 3. The Attempt at a Solution...
  41. K

    Electric field strength and electric potential in a sphere

    Given a solid metal sphere where all the positive charges are distributed evenly on the surface of the metal sphere. My textbook says that there is no electric field strength in the middle of the metal sphere because the charge = 0. However, my understanding is that wouldn't the center of the...
  42. M

    Electrical field strength problem

    I have completed the force column in the table however I am not sure what the question is asking me for the field strength calculation. am i to use the 25μC charge or the 8μC charge in the formula 1/4∏ε x Q/r^2, this may be obvious to someone with more experience of these questions, Thanks
  43. A

    Magnetic field strength problem

    http://s3.amazonaws.com/answer-board-image/2924bffb-da01-4543-9697-b67da02e5a5a.jpeg The picture above shows four square regions. Each of the four regions may have its own uniform magnetic field. If there is a uniform magnetic field in a region, the field is directed either into or out of the...
  44. S

    Magnetic field strength effected by insulation of wire

    Hello, Suppose there are two conductors carrying currents. One of them is bare conductor and the other has insulation. Now magnetic field will be created around them due to the current flow through them. What will be the condition of magnetic field strength around them? They have same field...
  45. O

    Finding the net field strength due to a line of charge

    I want to apologize ahead of time for my apparent inability to get LaTeX to display properly. Homework Statement λ = 3.8 x 10^(-6) C/m R = 32m r = magnitude of the hypotenuse (the book's convention, a poor choice IMHO) r = \sqrt{R^2 + x^2} k = 8.988 x 10^9 P:(0,-32) cosθ = x/r a→∞...
  46. G

    Electric field strength for a radial field.

    Homework Statement Q. A metal sphere of radius 20 cm carries a positive charge of 2.0 μC. a. What is the electric field strength at a distance of 25 cm from the centre of the sphere? b. An identical metal sphere carrying a negative charge of 1.0 μC is placed next to the first sphere. There...
  47. Darth Frodo

    Electric Field Strength problem.

    Homework Statement 2 point charges are situated 45nm apart in a vacuum. Charge A is +8μC and charge B is -25μC. X is a point 8nm from A. Calculate the electric field strength at point X only due to A (Ans is 1.2 x 10^9 N/C) Calculate the overall electric field strength at point X due to...
  48. P

    Electric Field Strength magnitude

    Hi, Four point charges of equal magnitude are held at the corners of a square. The length of each side of the square is 2a and the sign of the charges are the following: Two positive charges on the top two corners of the square and two negative charges on the bottom two corners of the square...
  49. I

    Calculating Electric Field Strength using Electric Potential?

    Homework Statement How do I calculate the Field Strength if I know the Potential? Homework Equations E = -\nablaV V = Electric Potential E = Electric Field Strength The Attempt at a Solution There's a problem in which I calculated the Potential, it's constant however. So according...
  50. M

    How does the magnetic field strength decay(radially) inside a solenoid coil?

    I'm looking at redesigning a hydraulic solenoid valve with the aim of reducing the package size. The solenoid coil is by far the largest component of the device, with about 4000 coils arrayed in about 90 layers stacked on top of each other. I'm wondering if I can reduce the size by removing some...
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