Electric field Definition and 1000 Threads

An electric field (sometimes E-field) is the physical field that surrounds electrically-charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field for a system of charged particles. Electric fields originate from electric charges, or from time-varying magnetic fields. Electric fields and magnetic fields are both manifestations of the electromagnetic force, one of the four fundamental forces (or interactions) of nature.
Electric fields are important in many areas of physics, and are exploited practically in electrical technology. In atomic physics and chemistry, for instance, the electric field is the attractive force holding the atomic nucleus and electrons together in atoms. It is also the force responsible for chemical bonding between atoms that result in molecules.
Other applications of electric fields include motion detection via electric field proximity sensing and an increasing number of diagnostic and therapeutic medical uses.
The electric field is defined mathematically as a vector field that associates to each point in space the (electrostatic or Coulomb) force per unit of charge exerted on an infinitesimal positive test charge at rest at that point. The derived SI units for the electric field are volts per meter (V/m), exactly equivalent to newtons per coulomb (N/C).

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  1. Adeel Ahmad

    Finding Electric Field and Work at a Given Distance? Need help with Problem 1

    Need help with Problem 1 Homework Equations E = kq/r2 V = -W/q V = kq/r The Attempt at a Solution 1a. dE = kdq/rRSUP]2[/SUP] dq = p ds dE = kpds/R2 Not sure if I am right up to this point and don't know how to proceed. 1b. I think the electric field would be zero since the enclosed charge...
  2. JulienB

    Coordinates of the electric field vectors of a dipole

    Homework Statement Hi everybody! I might have solved that homework but I struggle to properly understand some steps, especially concerning the gradient and partial differentiation: The potential Φ(r) of an electric dipole located at the origin of a coordinate system is given by: \phi...
  3. yeezyseason3

    Deriving Electric Field Inside Plastic Rod Using Gauss's Law

    Homework Statement A straight circular plastic cylinder of length L and radius R (where R ≪ L) is irradiated with a beam of protons so that there is a total excess charge Q distributed uniformly throughout the cylinder. Find the electric field inside the cylinder, a distance r from the center...
  4. Jai Singh

    The net force on the charge placed at origin

    Ques: If infinite number of charges placed along x-axis .At x=1, 1μC , x=2, 2μC, x=3, 3μC so on. Find the net force on charge 1μC placed at origin.Formula used (1/4πε)*q1*q2/r² Solved from this formula but stuck in a series
  5. Kernul

    Electric field with electric potential

    Homework Statement A metallic hollow cylinder has a diameter of ##4.2 cm##. Along his axis there is a wire having a diameter of ##2.68 \mu m##(considering it as a hollow cylinder). Between the cylinder and the wire there is a voltage of ##855 V##. What is the electric field on the wire surface...
  6. bburke95

    Find Electron Current Through Iron Wire

    Homework Statement What electron current is driven through a 1.4-mm-diameter iron wire by a 0.070 V/m electric field? The mean time between collisions in iron is 5.2×10^−15s . A=1.5*10^-6 m^2 ne=8.5*10^28 m^-3 Homework Equations I know I need to use ie = neAVd, but I'm having trouble finding...
  7. JulienB

    Calculating Work Done by an Electron in an Electric Field

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  8. ing_it

    Intensity of an electric field near a wire -- With and without Gauss' Law

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  9. J

    Electric field strength in metal sphere

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  10. Kernul

    Electric Field in all of space from charges along the Z-axis

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  11. D

    Electric field due to a charged sheet

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  12. Kernul

    How Can Constant Electric Field Be Achieved in a Spherical Charge Distribution?

    Homework Statement A volumetric charge density ##\rho = \frac{A}{r}## is distributed in the spheric region ##r_1 < r < r_2## (##A## is constant). A point charge ##q## is located in the center of the sphere (##r = 0##). What should be the value of ##A## so that the module of the electric field...
  13. Shima97

    Electroreception, Electric field and charges

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  14. K

    Electric field and electromagnetic waves

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  15. P

    Finding an electric field at a point from a line of charge

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  16. Biker

    Calculating the work done in an electric field

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  17. S

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  18. S

    Electric Field along bisector of charged line (w/error)

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  19. T

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  20. S

    Magnitute and Direction of Electric Field Based on Particle

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  21. person_random_normal

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  22. Titan97

    A conducting shell kept in a uniform electric field

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  23. D

    Electric Field between two Charges

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  24. A

    Approximations used in solving for the electric field

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  25. P

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  26. 1

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  27. S

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  28. S

    Magnitude of the E-Field at the center of curvature

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  29. S

    Electric field lines from a metal shell and sphere

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  30. D

    Transfer of kinetic energy from particle to electric field

    If an electron in an excited wave form passes thru an electric field , can it lose kinetic energy in doing so.?
  31. L

    Electric field at a point inside of a uniformly charged ball

    As the name of the thread says, I am wondering what would the amount and the direction of the electric field at some point in the uniformly charged ball of radius R(it has a constant charge volume density) be at the distance r from the centre of the ball. Does anyone know what would they be? I...
  32. C

    Electric field in the vicinity of an antenna

    I don't know why I was persuaded that in the free space, the electric field of an EM wave is always orthogonal to the direction of propagation. I've recently read my old textbook, and found that this is true only when the wave is far from the emitting source. But if I've understood right the...
  33. K

    Is this how to attempt this problem on electric field strength

    Homework Statement Two parallel plates at -50kV and 100kV have separation 35cm. a proton is placed between the plates. calculate the electric field strength between the plates Homework Equations E=v/d The Attempt at a Solution 100kV--50kV=150kV 150x10^3/0.35=428571.4N/C
  34. A

    Deriving electric field with given potential

    Homework Statement Given that the potential of dipole is equal to: V(\vec{r})=\frac{\vec{p}\vec{r}}{4\pi\epsilon_0 r^3} show that the electric field is equal to: \vec{E}(\vec{r})=\frac{1}{4\pi\epsilon_0}(\frac{3(\vec{p}\vec{r})\vec{r}}{r^5}-\frac{\vec{p}}{r^3}) Homework Equations...
  35. C

    Electric field inside a conductor

    Suppose there is a metal disk with an initial excess of charge represented by the four red electrons. Naturally, they reach their equilibrium position on the surface. After this, a new electron (the green one) is added exactly at the center. The repelling forces from the red charges cancel each...
  36. F

    Calculating Electric Field at Multiple Points in a Charged System

    Homework Statement In the figure (attached), find the magnitude and direction of the electric field at points A, B, C and D. Homework Equations E = kQ / r^2 The Attempt at a Solution I'm just a little lost with the directions/if I need to be including angles so for point A: E = k 7.5e^5C /...
  37. Icy98

    Movement of electron in an electric field

    Homework Statement An electron has an initial velocity of 5.00 x 10^6 m/s in a uniform 2.00 x 10^5 N/C strength electric field. The field accelerates the electron in the direction opposite to its initial velocity. (a) What is the direction of the electric field? (b) How far does the electron...
  38. L

    Overall Electric flux of a rigid body

    When we looked at some closed surface, we defined the overall electric flux of that surface as the sum of all infinitesimal fluxes of all the infinitesimal surfaces that make the quoted closed surface. Does that change if we do not have a closed surface, but a rigid body such as, let's say, a...
  39. A

    Electric Field distribution around two-conductor cable

    What is electric field distribution around two conductor cable connected to DC power supply? Assume power supply is isolated and not grounded. Assume cable is straight. Case 1: no current runs through the cable. One wire is positive, another – negative. Negative or zero? If we think in terms of...
  40. K

    I How Does Jackson's Use of Manifolds Enhance Understanding of Electrodynamics?

    This is from Jackson, "Electrodynamics" a field is a fuction mapping phi: M -> T, x -> phi(x) from a base manifold M into a target manifold T. field X: R3 * R1 -> R3 x(r,t) ->X(x)I think this is eucledian R4 to R3 so I wonder why Jackson explained this with the concept of manifolds? Is it...
  41. M

    How do you find electric field given only time and distance?

    Homework Statement Two charged plates are 2mm apart. An electron escapes from the negatively charged plate and reaches the positively charged plates in 1.2x10^-8 seconds. Find the electric field between the plates. Homework Equations E=V/d eV= + or - 1.6x10^-19 C The Attempt at a Solution...
  42. B

    Solve Gauss' Law Question: Find Max Acceleration of Two Balls

    Homework Statement Consider two balls of equal radii and masses but opposite charges, distributed uniformly over their volumes. Initially, the balls are at rest and far away from one another. Due to the Coulomb attraction, the balls start moving towards each other. The balls can be treated as...
  43. Dimani4

    A Fermi energy Ef changes with applied electric field?

    Hi people, I don't understand why when we apply the electric field to the metal Ef remains the same. Ef as translation energy of electrons remains the same but we accelerate the electrons with applied electric field so the translation energy increases too? In other hand according the formula...
  44. M

    Charged mass hanging in electric field

    Homework Statement My teacher came yesterday, and put in the board one exercise, just the scheme, not aditional data, i have one picture of the scheme Homework Equations The given E its mean to electric field The Attempt at a Solution I need some help, go get the right way into problem [/B]
  45. Titan97

    Calculating Induced EMF in a Circular Region with Decreasing Magnetic Field

    Homework Statement In the below figure, magnetic field is decreasing at a rate of 1.5T/s in a circular region of radius 2m. EMF developed in the rod will be? Homework Equations $$V_{\text{induced}}=-A\frac{\mathrm{d}B}{\mathrm{d}t}$$ The Attempt at a Solution I tried using induced electric...
  46. H

    What Direction Does the Electric Field Point in This Scenario?

    Homework Statement beam of protons moving in +x direction at speed v electric field is perpendicular to magnetic field magnetic field in +y direction no deflection What direction/sign has the electric field? Homework Equations not looking for numerical solutions The Attempt at a Solution...
  47. Physics Dad

    Electric Field Strength - Assignment Question

    Homework Statement The Nucleus of a helium ion contains two protons approximately 5x10-15m apart. They can be considered to be surrounded by one orbiting electron approximately 5x10-11m away. Calculate the following: a) The electrostatic force between the two protons b) The electrostatic...
  48. P

    Electric Field Homework: Rank Protons by Acceleration

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  49. B

    Electric field between inner and outer cylinder

    Homework Statement A capacitor is constructed of two long concentric metal cylinders, each having length of 1.0 meters. The inner cylinder has a radius R1 = 1.0 cm, and the outer cylinder has a radius R2 = 1.25 cm. The hollow space between the two cylinders is filled with nylon having a...
  50. Drakkith

    Conductor in an External Electric Field

    I just had a test question in my E&M class that asked what would happen to a conductor when placed in an external electric field. One of the "correct" answers was that all of the free electrons would move to the surface of the conductor. I understand that the free electrons would rearrange...
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