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).

View More On Wikipedia.org
Recent contents Top users
  1. meher4real

    Electric field between two parallel plates

    [New poster has been reminded to show their best efforts to work the schoolwork problem when starting a homework thread] My question is : An electron beam with velocity vector v = (0; 0.6x10^8 ;0) m.s enters between two oppositely charged plates parallel to the xz plane. - How large is the...
  2. eric11201120

    Expression for Electric Field Outside Sphere

    I'm not quite sure where to start. If someone could help me I would very much appreciate it.
  3. E

    Engineering Understanding the Relationship Between Voltage and Electric Field

    Hi guys ! I am taking phys102 course .I figured out that i didnt fully understand the concept that is the Voltage. Please look at this question. In this case we can see that there is no voltage in point C and there is no electric field is in point D and as you know V=U/q .So i always thought...
  4. S

    How does the strength of an electric field relate to its direction?

    I understand that negative charges create electric fields pointing inwards, and positive charges create electric fields pointing outwards, but what does this have to do with field stength? What is the relationship between field strength (flux?) and direction?
  5. H

    What is the maximum electric field magnitude between the cylinders?

    I used a couple ways to do this question, but I got neither correct. Can someone help, please? Thank you. 1. E= V/r = 700 / (60*10^-3) = 11667 (very far from the given answer) 2. E = (-kQ/r)⋅ dr = kQ/r^2 = kQ/ [( 1/20/ 10^-3)^2 - (1/80/10^-3)^2] (For this method, I stuck...
  6. V

    Find electric field intensity/density with given potential difference

  7. H

    Is the Induced Electric Field Proportional to Radius in a Cylindrical Region?

    I used the equation below and the attachment to rationalize. https://www.physicsforums.com/attachments/282163
  8. A

    Moving electric field effect on dielectric/gas

    So I was wondering, can a moving electric field produce a drag force on gas for example similar to that which would result from physical blades moving the gas. Electric field applied to a dielectric if not as strong as to produce breakdown produces polarization. I wonder can this polarization...
  9. jay_chay22

    Find electric field separating two charged masses suspended on strings

    Please help me on this question I have tried to do it many times but I end up getting the wrong answers. I have show my work what I have done.
  10. S

    Electric Field Intensity: Intersecting E-fields Explained

    This the photo of my textbook, Here In the derivation of Electric Field Intensity due to an infinitely long straight uniformly charged wire - In the figure 1(c).20 Vector E1 and vector E2 are electric fields at point P due to the two line elements as shown in the figure 1(c).20. But, in this...
  11. Mayan Fung

    Electric field acting on the source charge

    I am reading Griffith's textbook on EM. There is a problem asking to find the force acting on the northern hemisphere by the southern hemisphere of a uniformly charged sphere. The solution idea is to find the expression of the E field by Gauss's law and integrate the force over the northern...
  12. Mayhem

    Electrostatics: Coloumb's law and the Electric Field

    Hi. How does the charge ##q## relate to the charges ##q_1, q_2## (see equations). For example, if ##q_1## is an electron and ##q_2## is a proton, is ##q## just a product or sum or something else of the two? Also, in Columb's law, how would I conceptualize charges ##q_1, q_2## in a system of a...
  13. P

    Work Done on A Proton in an Electric Field

    W=-qEd =-(1.6*10^-19)(23)(0.75) = -2.76*10^-18 J However, the answer is 2.76*10^-18 J. Why is the word done positive and not negative? Since it's traveling in the same direction as the electric field, shouldn't it be negative work?
  14. H

    Determining electric field using gauss's law--different distributions

    These are the 4 distributions shown, and I have to determine which two distributions (or none at all) can use Gauss's law to determine the electric field. So electric flux = EA = Q/electric constant. Since all of them have charges, I could do something like Q/(A*electric constant) to get the...
  15. naviakam

    I Estimating Particle Number in an Electric Field

    In an electric field ##E## if the energy of charged particle (ion) is formulated as ##W=qEr## where ##r## is the distance, how the number of particles is estimated?
  16. Fikremariam

    Electric Field -- Potential between the ends of a 2 meter stick

    I tried to find the charge from the formula v=k q/r and apply it to find the field but couldn't be sure
  17. robphy

    Insights The Electric Field Seen by an Observer: A Relativistic Calculation with Tensors

    Continue reading...
  18. P

    Work done by electric field to move capacitor plate

    so the result I got is the energy lost by the field right??
  19. P

    Problem on induced electric field, electrodynamics

    The problem is shown above, the hint to solve the problem is below. See the hint if it is difficult for you to imagine what is going on. I am assuming the diagram in the hint shows what's happening when the mass is falling at terminal velocity. I have quite a few questions. 1. How do the wheels...
  20. T

    Electric field inside a charged ring

    I am just a bit confused here. Would doing this even change the electric field direction at the center at all? I'm thinking no, but a bit of direction would be appreciated. This problem is really simple, I'm just a bit confused.
  21. A

    I Electric Field seen by an observer in motion

    In Robert Wald's General Relativity textbook page 64 reads: __________________________ In prerelativity physics, the electric field ##\vec{E}## and magnetic field ##\vec{B}## each are spatial vectors. In special relativity these fields are combined into a single spacetime tensor field ##F_{ab}##...
  22. T

    POTENTIAL DIFFERENCE AND ELECTRIC FIELD HOMEWORK

    I tried following the formula but it wasn’t correct. I’m sure I could get it if I had an example as I’m sure this must be a simple question for other people I was just unsure if I was doing it correct.
  23. Z

    Potential Gradient for individual charges and parallel plates?

    In my book, the potential gradient for a charge placed anywhere in space is defined as: E = -V/r HOWEVER, for parallel plate (capacitors) the potential gradient is defined as E = V/d (V being the potential difference). How come there's no negative sign for the potential gradient of the parallel...
  24. Ibby321

    Vertical motion through an electric field

    I know that the answer is 0 J (no NET work was done) because there is symmetry to the problem and this symmetry comes from the fact that the direction of force changes, BUT I don’t know why the force changes (I have an idea; TBD below in #4). When I did this problem I thought I could find the...
  25. I

    Electric Field from a Charged Semicircular Rod

    Charge QQ is uniformly distributed along a thin, flexible rod of length LL. The rod is then bent into the semicircle shown in the figure (Figure 1).Find an expression for the electric field E⃗ E→ at the center of the semicircle. Hint: A small piece of arc length ΔsΔs spans a small angle...
  26. Costweist

    Changes in electric field lines as a result of an oscillating charge

    The last couple of days I’ve been troubled with a specific part of electromagnetism. How will electric field lines be affected by an oscillating charge? More specific, what will happen with the “amplitude” of a wave in an electrical field line as the wave propagate away from the charge? 1. Will...
  27. B

    How to create an Electric Field?

    Dear friends, First of all I have one question! As per Figure 1, how to implement electrical connection in real life which are seen inside Red Box? and what is the meaning of grounding the other terminal? Figure 1 And the second thing is that, I want to create and electric field on copper...
  28. H

    Question about the force exerted by a uniform electric field on a dipole

    I think the answe should be C as shown in the attachment.
  29. F

    Understanding the Electric Field of Two Spheres: A Scientific Approach

    I am not quite sure how to present my answer in the form of a function with relation to the distance from the centre. What I got so far is the E1 and E2, for the internal and external sphere respectively. For internal sphere, the charge is volume * 𝜌, so it is $$ \frac{4\pi r^{3}}{3} * 𝜌$$...
  30. B

    Energy within an electric field

    I am trying to calculate the energy within an electric field that is generated between two plates by a pulse but am unsure of what voltage value to use. The pulse is a sinc wave. I am assuming I can still use the equation ## E= \frac{1}{2}CV^2 ##. I know the ##V_{rms}## and ##V_{max}## which...
  31. F

    Finding Electric field E due to an arc

    I need to account for tension, weight, and repulsion. For the tension, I can draw the x and y component of Tmax and see that the x components of the 2 tensions Tmax will cancel out, and there are 2 y components of the Tmax to factor in. Weight is just F = mg, where g is acceleration due to...
  32. A

    Electric Field Shielding: Does a Conductor Shield Inside?

    Hi. I was reading about conductors in electrostatic equilibrium and how it makes sense that they have zero electric field inside the material even when an external charge is brought near. The charge density of the material just rearranges itself to cancel. Then I searched for hollow conductors...
  33. C

    Can't solve an equation (Deflection of electrons in electrostatic field)

    Hello everyone! I've tried everything but the equation (3) in "Deflection of electrons in electrostatic field" is impossible. Can someone at least hint me to a a way the composed it ?
  34. Kaguro

    Concept of electric field and hollow conductors

    I think: Due to charge q, there will be a field in region 1, very much dependent on position of q. The inner surface charge density of irregular conductor is also dependent on the position( so that it could cancel the field of charge and E=0 inside body of irregular conductor). The outer...
  35. M

    Electric field of non-conducting cylinder

    a) I have calculated (1) λ = ρA = ρπr^2 = 2.49 * 10^-10 C/m and placed it into (2) yielding E = λ / (2πεx^2) = 106.73 N/C. This doesn't seem to be correct by the feedback, however. b) Here just to consider the proportion of the cylinder mass constrained by y.
  36. sep1231

    Electric Field as potential gradient

    I know that the electric field is directed from Q to P, but I'm not sure which magnitud is greater, I tried this
  37. S

    Gauss' Law: Understand How to Calculate Flux

    Hello everybody To calculate the flux for the electric field I need the gauss law. There are two formula one with the integration over some area and the other is Q/e0. When do I have to use which one?
  38. TechieDork

    Find an expression for a magnetic field from a given electric field

    Here this is my attempt : Reference Textbook : Zangwill's Modern Electrodynamics I stuck at the last step , I really have no idea what to do next.
  39. A

    Electric Field from Non-Uniformly Polarized Sphere

    Solving for the volume and surface bound charge densities was easy using equations 1) and 2). The polarization only has an r component so ##ρ_b=-\frac 1 {r^2} \frac {d} {dr} (r^2 \vec P)=-α(n+2)r^{n-1}##, and ##\hat n=\hat r## so ##σ_b=αa^n##. To find ##\vec E## I intend to use equation 3)...
  40. PhysicsTest

    To find the parameters of velocity in an electric field

    i have drawn the E field as below, hence the F will be in the upward direction for electron a. Using energy is constant, the velocity ##v_x## as it crosses A is ##0.5mv_x^2 = q*V_a## ##v_x = \sqrt{(\frac{2qV_a} m)} m/s## one doubt i have here is, the question mentions electrons, but i have...
  41. badluckmath

    Electric Field of two line charges

    I'm trying to solve this, but i don't really know how to start this problem. There are two line charges and i must find the E. Field on the center.
  42. J

    What effects does an electric field have on potential energy?

    Like an electric field is applying a sort of force on a particle. I was wondering if this at all impacts the potential energy of a particle. For instance, when the force of gravity does work on an object, its potential energy changes as a consequence. Would it be the same thing here?
  43. PhysicsTest

    Find the electric field from charge density

    There is a section in the BJT explanation the charge density and the corresponding electric field graphs. But i was not sure how the electric field is derived and hence i started deriving it. Please correct me if my understanding is wrong in posting the question It is an ##npn## BJT. My...
  44. B

    Understanding the electric field of a sphere with a hole

    Here's an image. O and O' are the respective centers, a is the distance between them, r is the distance from the center of the sphere to P, and r' = r - a, the distance from O' to P. The approach (which I don't understnad) given is to use Gauss' Law and superposition, so that we calculate the...
  45. greg_rack

    The electric field between two adjacent uniformly charged hemispheres

    here is the situation Hi guys, I should illustrate the motion of an electron in both cases, but I cannot really understand how will the field be like in the gap between the two(filled) hemispheres(conductor and non). Another thing is: for the conductive hemispheres, does it make any sense to...
  46. Kaguro

    Poynting vector and electric field

    The Poynting vector $$\vec S=\frac{1}{\mu_0} \vec E \times \vec B$$ gives the power per unit area. If I need this in terms of electric field only,I should be able to write B=E/c (for EM wave) Assuming they're perpendicular, ##S =\frac{1}{\mu_0 c}E^2##. Now, ##c=\frac{1}{\sqrt{\mu_0 \epsilon_0}}...
  47. G

    Find the electric field from polarization

    Attempt at solution: a) Since I need help with b) this section can be skipped. Results : ##ρ_{psa} = -Pa ## ##ρ_{psb} = Pb ## ##ρ_{p} = \frac {-1}{R^2} \frac {∂(R^2PR)}{∂R} = -3P ## b) This is where I am unsure (first time using gauss law for P) so I need some confirmation here: ## \int...
  48. P

    Electrostatics: Calculate the Electric Field near a Charged Ring

    I have the problem with my solution. I don't know it is correct. Could somebody check it?
  49. huszarerik

    Electric field lines between a point-charge and a conducting sheet

    figure 1: → I don't understand how to approach this problem. Basically it asks for the distance r.I think I should use Gauss's law, but I've been thinking about the shape of the gaussian surface and I'm not sure about how it should look or where I should place it. Any help would be useful...
  50. J

    I Is the electric field of an atom a superposition or mean of electron positions?

    We usually think about atomic orbital as wave(function), but it was created from e.g. electron and proton approaching ~10^-10m (or much more for Rydberg atoms), and electron has associated electric field. This wavefunction also describes probability distribution for finding electron (confirmed...
Back
Top