What is Electric field: Definition and 1000 Discussions

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. N

    Electric field at the centre of a ball

    Question : Find the electric field at the centre of a ball of radius R with volume charge density rho = a.r, where a is a constant vector and r is a radius vector drawn from ball's centre. Relevant Equations and attempt at solution : I used the basic formula for electric field due to...
  2. Quadrat

    Electron passing through a magnetic and an electric field

    Homework Statement An electron with velocity ##\vec{v}_0=8.7*10^4(m/s)## (in the î direction) passing through an area with a uniform magnetic field ##\vec{B}=0.80 T## (in the negative k̂ direction). There's also a uniform electric field in this area. What is the magnitude and direction of...
  3. nishant mudgal

    Electric Field Lines: Can Charges Move on Conductors?

    sir, we know that the electric field lines are perpendicular to the surface of the conductor ,it means charges are rest on the surface of the conductor ,there is no work done. if we create an electric field such that the electric field lines are at a different angle to the surface of the...
  4. B

    Creating an electric field with a battery

    If I attach a battery to two parallel plates to create an electric field between the plates, will the electric field last for the lifetime of the battery?
  5. B

    Determine the Electric Field

    Homework Statement An electric field with a magnitude of 2.5N directed to the left, acts on a negative charge of -5.0C. Determine the electric field in which the charge is located. Give. FE=2.5N q=-5.0CHomework Equations FE[/B]=qε The Attempt at a Solution ε[/B]=2.5N/5.0C=0.5N/C. I don't...
  6. RoboNerd

    Question about electric field doing work

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  7. EmilyBergendahl

    Electric Potential Difference during thunder storm

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  8. W

    Non-uniform electric field flux through a cube

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  9. M

    I Uncovering the Mystery of the Electric Field of a Dipole Antenna

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  10. E

    Can a strong electric field ionize an atom?

    Metals have a work function which is the minimum energy needed to ionize an electron. I assume that the energy need is simply the energy difference of the two highest energy levels of a particular metal. This is all well and good and can be accomplished by absorbing a photon of that specific...
  11. W

    Electric field due to a charged square

    Homework Statement there is a square on the XoY plane, centered at the origin (just outlines of the square) it has a charge Q (Q>0) and side 2L, i must evaluate the electric field along the z axis. see attached image Homework Equations E=k*q/r^2 The Attempt at a Solution So first i divided...
  12. W

    Oscillating charges in an electric field

    I don't have a single problem, my teachers use this a lot. a few examples, are an uniformely charged circle and a point charge in the middle, where if you move the point charge a small distance perpendicular to the circle, it would begin to oscilate, and i need to find the frequency of...
  13. blintaro

    Electric field within solenoid

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  14. E

    Find the magnetic field in vacuum given an electric field

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  15. T

    Curvature of electric field around center of a quadrupole

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  16. D

    Direction of the induced electric field?

    If a time varying magnetic field exists in vertically downwards direction in a region A, an electric field is induced in the direction perpendicular to it i.e. in horizontal plane. How to find the direction of the E field in the horizontal plane?What factors decide the direction of the E field...
  17. Ian Baughman

    Electric Fields (Uniformly Charged Plates)

    Homework Statement In the figure two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have excess surface charge densities of opposite signs and magnitude 7.76 × 10-22 C/m2. What is the magnitude of the electric field at points (a) to the left of...
  18. steroidjunkie

    Metal sphere on a thread in a horizontal electric field

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  19. T

    Electric field inside a non uniform spherical distribution.

    Homework Statement Let ρ(r)= Qr/πR4 be the charge density distribution for a solid sphere of radius R and total charge Q.For a point 'P' inside the sphere at distance r1 from the centre of the sphere, the magnitude of electric field is ? A) 0 B) Q/4πε°(r1)2 C) Q(r1)2/4πε°R4 D)...
  20. O

    Electric Field Unchanged in Parallel Plate Condenser w/ Varying Distance

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  21. Curieuse

    Potential Energy for dipole in Electric Field

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  22. 1

    Why does the point experience NEGATIVE field strength?

    Hi, i'm looking for an explanation to this answer of a past paper that I'm doing, it's from OCR (A level) G485, question 1 b ii) the question on top, and answer on bottom i don't understand why would the point experience a negative electric field strength when it's getting closer to a...
  23. T

    Electric field of a disk & u-substitution

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  24. C

    Another electric field question

    The first part of the above image is the question from the text, and below that is information from the solutions manual. I understand why we broke the components up into the x and y, I understand how we triangulated the distance between the center of our coordinate system and the charge to get...
  25. C

    Electric Field question - Why is this answer negative

    Hello. The first image is the question, the second image is from the solutions manual. I don't understand why these answers are negative. Anyone have a clue?
  26. F

    The magnitude of the electric field

    Homework Statement Calculate the magnitude of the electric field at the center of a square 42.5cm on a side if one corner is occupied by a −38.2μC charge and the other three are occupied by −27.0μC charges. Homework EquationsThe Attempt at a Solution E=k(q/r^2) the direction of the electric...
  27. C

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  28. Biker

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  29. I

    Why Does a Negative Ion Move Towards the Anode in a Parallel Plate Capacitor?

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  30. B

    Electron shell further away from nucleus higher Energy lvl?

    Using electrical potential energy =1/4πεo Q1Q2/r , a particle further away from nucleus has lower magnitude of energy Using coulomb's law, a particle further away from nucleus experiences weaker attraction, hence less energy is needed to maintain orbit* around that e-shell compared to a...
  31. S

    Questions about electric fields, voltage and electric energy

    1. If e.m.f is NOT a force, but actually energy – and e.m.f is measured in Voltage – then why is p.d. (V) NOT used up? Since we know energy *does* get used up by the component. I know the electrons are just the medium – energy carriers – but Voltage doesn’t mean number of electrons; it means...
  32. J

    Magnitude and DIRECTION of electric field of a square.

    Homework Statement Calculate the magnitude of the electric field at the center of a square 42.5cm on a side if one corner is occupied by a −38.2μC charge and the other three are occupied by −26.9μC charges. (This part done) Choose the correct direction of the electric field at the center of...
  33. T

    Finding the Electric Field of a Hollow Cylindrical Conductor

    I am trying to find the electric field of a hollow, open-ended, thin-walled cylindrical conductor. I am trying to solve something regarding LINACs: Assume we have an isolated, hollow, open-ended, thin-walled cylindrical conductor, with a net charge. The net electric field within the...
  34. Ryaners

    Electric field in two concentric conducting cylinders

    Homework Statement Two concentric cylindrical conducting shells of length L are separated by a vacuum. The inner shell has surface charge density +σ and radius ra. The outer shell has radius rb. Using Gauss’ Law, as a function of radius r find: The direction and magnitude of electric field...
  35. Adeel Ahmad

    Electric Field, Potential, and Work at a Point

    Homework Statement Homework Equations E = kq/r2 V = -∫ E ⋅ ds W = -Vq The Attempt at a Solution a) I just summed up the electric fields: +ek/a2 +ek/a2 -ek/a2 so I get +ek/a2 as a result. Not sure if this is correct since -e has a y component so I was thinking to use sin but not sure which...
  36. 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...
  37. 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...
  38. 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...
  39. 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
  40. 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...
  41. 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...
  42. JulienB

    Calculating Work Done by an Electron in an Electric Field

    Homework Statement Hi everybody! Here I am with another problem of electromagnetism, I'd like to make sure I understand it properly! An electron is moved 1 meter towards an homogeneous electric field of strength 1N/C. How big is the work done for this motion? Homework Equations F = q \cdot...
  43. ing_it

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

    Homework Statement We have a wire of the length L=0.2m which is uniformly charged with a linear density of Lambda = 3nC/cm. Find the intensity (E) of the electric field in point A1 whose perpendicular distance from the wire is a=0.05m. The wire is in a vacuum. Compare the intensity with the...
  44. J

    Electric field strength in metal sphere

    1. Homework Statement Why is there no electric field strength in a metal sphere? Is it because the sum of the individial electric field strength of the charges in the sphere is zero? How is that possible? Homework EquationsThe Attempt at a Solution
  45. Kernul

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

    Homework Statement A charge is distributed evenly along the ##z## axis with a density ##\lambda = 3 \frac{\mu C}{m}##. There is also a cylinder with radius ##r = 2## and on his side there is a superficial density charge of ##\sigma = -\left( \frac{1.5}{4 \pi} \right) \frac{\mu C}{m^2}##. Both...
  46. D

    Electric field due to a charged sheet

    When a plane sheet is given a charge Q the electric field at any point around it is given as ##E = \frac{\sigma}{\epsilon_0}##. Thus mathematically it can be concluded that the electric field is constant everywhere and is independent of distance of the point from the sheet. But what logical...
  47. 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...
  48. Shima97

    Electroreception, Electric field and charges

    Hi guys. This is my question. I just wondering what equation that I'm suppose to use. Homework Statement What is the maximum distance at which a shark can detect the electric signal emitted by the trout’s heart if the predator is at a point on an axis passing through the centre of the heart...
  49. K

    Electric field and electromagnetic waves

    (sorry for my poor english) I've read that a electromagnetic wave only exists in a particular point of space if in such a point there is a nonlinear change of the electric field in respect to time. Then I took a graph calculator and I derived Coulombs equation for the electric field. The results...
  50. P

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

    Homework Statement A thin insulating rod with charge density lambda=+5nC/m is arranged inside a thin conducting cylindrical shell of radius r =3 cm. The rod and the shell are on the same axis, and infinite in length. What is electric field at point p? 6cm from the central axis. Homework...
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