What is Electrostatic field: Definition and 70 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. E

    I DC current flows in a wire when two loops are brought close by?

    Hi all, I have a question on the DC current flows, when two loops are close by. Consider a battery driving a loop with a finite resistance. There are charges on the surface of the loop, which exerts forces to direct the flow of the DC current. The changes also produce an electrostatic field...
  2. rokiboxofficial Ref

    Surface density of the charges induced on the bases of the cylinder

    The correct answer to this problem is: ##\sigma = \varepsilon_0E\frac{\varepsilon-1}{\varepsilon}## Here is my attempt to solve it, please tell me what is my mistake? ##E_{in} = E_{out} - E_{ind}## ##E_{ind} = E_{out} - E_{in}## ##E_{in} = \frac{E_{out}}{\varepsilon}## ##E_{ind} = E_{out} -...
  3. Philip Koeck

    I Surface charge of neutral solids

    Also referring to the post by @Kostik plus answers, I'm wondering about surface charges of neutral solids such as metals or carbon, for example. I only want to discuss large scale effects so that the solid can be treated as continuous. The atomic structure is averaged out. I also assume that...
  4. Ahmed1029

    I Average electrostatic field over a spherical volume

    this formula in the picture is the average electrostatic field over a spherical volume of radius R. It is the same expression of the electrostatic field, at the (position) of the point charge, of a volume of charge of uniform density whole entire charge is equal to (negative)q. My question is...
  5. E

    B Virtual photons as force carriers

    (My multipart question is from a very naive perspective, so sorry if it is rife with misunderstandings. Please answer conceptually, with as few & as simple equations as possible. I think that all of the answers to these questions should be understandable to a high schooler, though maybe the...
  6. MichPod

    I Calculating Force & Acceleration in Electrostatic Field (B=0)

    For a case of electrostatic field (B is equal zero), how should the force acting on a moving charge be calculated if we want to take into account all the relativistic effects? Also would it be correct to calculate the acceleration of the charge as a=F/m, or should some other formula be used? For...
  7. V

    Magnitude of electric field E on a concentric spherical shell

    The only explanation that I have seen in textbooks is that since the outer spherical shell is symmetrical relative to internal charged spherical shell so field every where on the outer shell is same in magnitude at every point on it. I can understand that electric field needs to be...
  8. 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 ?
  9. G

    Electrostatic field of a sphere

    What is the electrostatic field of a non-conductive sphere (it's radius is R) which has a density charge distribution inside? ρ0 and R are parameters. I started solving this with Gauss's law: then: Solving the integral: This means the electrostatic field of the sphere in r is: Can you...
  10. J

    Propagation speed of the electrostatic field

    I have a proton and an electron at a certain distance from it. The proton exerts an electrostatic force on the electron. I then neutralize the proton's charge by firing another electron at it from behind. How long does it take for the first electron to sense the change?
  11. T

    Capacitor and electrostatic field

    Is there any electrostatic field around the leads of a charged capacitor? Let's take just the negative one. If I take a piece of tissue and put close to that terminal it will attract or repel the paper? And if not, why?
  12. P

    I Is it possible to detect an electrostatic field?

    If the electron creates an electric field around itself that can be detected,then the electrostatic field is real? So why was not the "virtual" photon found?
  13. C

    Floating potential of a conductor in an electrical field

    I'm interested in the following general question: Assume x,y,z is an axes system, and that the y-z plane is occupied by a conductive plate at a known potential V with respect to the earth. Now, a conductive material M of neutral global electrical charge is placed at some distance of the plate...
  14. alan123hk

    Experiment for the existence of electrostatic field

    I am still puzzled by the issue of existence of electrostatic field. According to the classical electromagnetic theory, electrostatic field can be created by an electrically charged particle. The electrostatic field surrounding the electrically charged particle does not stop close to the...
  15. Q

    Cylindrical Coordinates: Line Integral Of Electrostatic Field

    Homework Statement An electrostatic field ## \mathbf{E}## in a particular region is expressed in cylindrical coordinates ## ( r, \theta, z)## as $$ \mathbf{E} = \frac{\sin{\theta}}{r^{2}} \mathbf{e}_{r} - \frac{\cos{\theta}}{r^{2}} \mathbf{e}_{\theta} $$ Where ##\mathbf{e}_{r}##...
  16. Sunanda

    Electric Potential due to a single point charge

    Please refer to the image attached. So, my doubt is: While calculating dW in the derivation, we know this work is being done by external force, because only then the unit positive charge can be made to move towards the charge +Q. So dW should be equal to Fext.dx but here in the book it is shown...
  17. D

    Creating a 2-D Electrostatic Field

    I've been reading the Feynman lectures in physics. In volume 2 chapter 7: http://www.feynmanlectures.caltech.edu/II_07.html he shows how to mathematically model a 2D electrostatic field. Is it possible to create an experiment that behaves the same way even with the complex variables? Thank you...
  18. terryds

    Divergence of electrostatic field?

    Homework Statement By Gauss' law, how is it able to obtain ## \nabla \cdot \vec{E} = \frac{\rho}{\epsilon_0} ## ? By Coulomb's law, ##\vec{E} = \frac{1}{4\pi\epsilon_0} \frac{q}{r^2} \hat{r}## I calculate the divergence of ##\frac{1}{r^2} \hat{r}## and get the result is zero That means the...
  19. X

    The electrostatic field of the Faraday cage

    I have a function of the cartesian coordinates x, y, z such that: f = a * ln|sin(px + iqy)| + by + c This equation should be describing the electric field nearby the wall of the Faraday cage. I solved the Laplace equation Δf = 0 and got : p = +/- q, so p = q. I should choose the constants...
  20. Nabin kalauni

    Is electric field always 0 if potential at a point is 0?

    I understand that if electric field at any point is 0, it implies that potential is constant not necessarily 0. But what if the potential at a point is 0? Does it imply that electric field is 0? Me and my friend had an argument and I am in the favour of electric field not being 0. Do I win guys...
  21. T

    Evaluating a simple electrostatic field integral

    Homework Statement I can find the e-field at point P. Homework Equations I get, easily enough, the correct integral solution (for the y-component, Ey - which is all I need to do): which I can see, informally, evaluates to: which is the correct answer. The Attempt at a Solution My...
  22. Rajeswar Panja

    Curl of electrostatic field vector

    I know that the curl of electrostatic field vector is zero. I want to know what will be the curl of electrostatic field at the edge region of the finite parallel plate capacitor?
  23. Curieuse

    Potential Energy for dipole in Electric Field

    Homework Statement To derive Potential Energy for dipole p in Electric Field E. 2. Homework Equations Potential Energy is the work done by the external agent in turning the angle of the dipole from the U=0 position to another position against the influence of the electric field applied...
  24. P

    Electrostatic field at the centre of a disk

    Homework Statement A thin conducting disc has radius a thickness b and electrical resistivity ρ. It is placed in a uniform time-dependent magnetic induction ##B = B_0 sin ωt## directed parallel to the axis of the disc. Assuming that ρ is large, find E at a distance r < a from the axis of the...
  25. Robsta

    Investigating the water-ice electret

    Hello all, I'm going to investigate the properties water when frozen in a strong electric field for a product I'm designing. A strong field will align the polar water molecules, and then they will freeze. I'm planning to create this strong field with a car battery attached to two parallel...
  26. S

    Calculating the time to reach a potential difference

    Homework Statement Q: Two conducting balls of radius 0.1 m are situated 3m apart in free space. Electrons are transferred from one ball to another at a rate of 10^13 per second. How long does it take for a p.d of 100 kv to develop? Homework Equations where ε0 is the electric constant...
  27. D

    Principle behind electrostatic shielding?

    if we have a solid conducting sphere with charges around it, then the elctric field inside the sphere is zero otherwise the electrons of the sphere would not be in equilibrium as there would be a net force acting on it. however if its a hollow sphere then why does the electric field inside the...
  28. ZapperZ

    Energy Gained by Charge in an Electrostatic Field - Comments

    ZapperZ submitted a new PF Insights post Energy Gained by Charge in an Electrostatic Field Continue reading the Original PF Insights Post.
  29. P

    Distribution of charge in hydrogen atom

    Suppose the hydrogen atom consists of a positive point charge (+e), located in the center of the atom, which is surrounded by a negative charge (-e), distributed in the space around it. The space distribution of the negative charge changes according to the law p=Ce^(−2r/R), where C is a...
  30. P

    Calculating electrostatic potential energy

    Homework Statement Consider potential field V(ρ, φ, z) = V_0/ρ in free space and cylindrical coordinates. Calculate electrostatic potential energy stored in half cylindrical shell defined by a≤ρ≤b, 0≤φ≤π and 0≤z≤h. Homework Equations W_E=½∫∫∫ρ_vVdV The Attempt at a Solution I have no idea...
  31. saba.shahin95

    Find net electric field in a wire?

    After solving this problem I ended up with--(2a is the length of the wire)(integral limit is from -a to +a) (x is the ⊥ distance from centre of the wire to a point P where we have to find the net field ) E[SUBx]= (1/4Πε)*(Q/2a)∫x.dy/(x^2+y^2)^3/2 P.S- sorry, I'm not able to upload the image of...
  32. G

    Electrostatics:Longitudinal charge density of conductors

    Homework Statement Three very long (theoretically infinite long) hollow cylindrical conductors, with radius a,b,c (c>b>a) are in vacuum. Inner and central conductor are charged, and outer conductor is grounded. Potentials of inner and central conductors with reference point relative to outer...
  33. B

    Electrostatic Field and Particle Motion: Homework Solution and Explanation

    Homework Statement Can someone confirm if I answered correctly? Question: Two small identical spheres each carrying a charge, +q C, are placed on the line LM as shown in the diagram: Describe how the intensity and direction of the electric field produced by the two charges varies: i) Along...
  34. T

    Electrostatic field at the square center

    I have just begun studying electrostatic and I'm trying to do this exercize: We have a square with charges +q , -2q, +2q, -q1)Compute the electrostatic field \vec{E}at the center of the square. I did this way : I find \vec{E_A}=\frac{q}{2 \pi \epsilon_0} \vec{u} {E_B}=\frac{-q}{ \pi...
  35. KiNGGeexD

    Electrostatic fields- What defines an electrostatic field?

    I have a question about electrostatic fields! I was given these two equationsE= k [xy xˆ + 2yz yˆ + 3xz zˆ] E= k[y^2 xˆ+ (2xy+ z^2)+ 2yzzˆ] And asked to determine if either could be an electrostatic field, I'm not asking how to solve this problem but I'm not sure what defines an...
  36. vanhees71

    Massless charged particle in electrostatic field

    Does anyone here know a source, where the equation of motion for a massless charged particle (which of course does not exist in Nature as far as we know) in a homogeneous electric field is actually solved? I googled, and there are some papers about this, but the equations are never actually...
  37. K

    Simple electrostatic field question

    Hey everyone, so I think my question will be relatively simple compared to what I've viewed elsewhere here. Basically, I am an adult taking grade 12 physics as self study, and for the most part I can work things out ok. I am planning on taking the diploma exam for my province in January...
  38. R

    What is this nature of Electrostatic Field ?

    Hi all, Work done to move a charge between two points in electrostatic field is independent of path taken. what is in this electrostatic force that is causing this? I mean how is it making it path independent? Does it has to do with the inverse-square nature of the field? or Its radially...
  39. B

    Expression of electrostatic field

    Homework Statement Why does this expression, given in cylindrical coordinates, rapresent an electrostatic field: $${\bf E(r)}=\frac{\alpha}{z^2}{\bf u_r}-2 \frac{\alpha r}{z^3}{\bf u_z} $$ Homework Equations The Attempt at a Solution I can't understand why the expression rapresent...
  40. M

    Electrostatic Field: Work Done by Electric Forces

    what is the work done by electric forces in moving a charge Q=1 nC from the origin to the point (1m, 1m, 1m) in the electrostatic field given by E=(x,y,z) = (x* (a sub x) + y^2*(a sub y) - (a sub z) V/m in the Cartesian coordinate system along the straight line joining two points?
  41. P

    Is electric potential always continuous in an electrostatic field?

    Is electric potential always continuous in an electrostatic field? I mean, does it suffer from discontinuity at any point?
  42. Z

    Past exam question about electrostatic field and potential

    Homework Statement Using Stoke’s theorem and the identities given, ∇x∇(Scalar)=0 deduce the relationship between electrostatic field E and potential ψ at a point in space, show that E = -∇ψ Homework Equations The Attempt at a Solution Does this question mean show a derivation...
  43. C

    Electrodynamics: Electrostatic field potencial in Cartesian coordinates

    Homework Statement It's given that absolute permitivity is a coordinate function: ε (x, y, z) = Asin(x)cos(y), where A=const Homework Equations We need to find an electrostatic field potential function \varphi in Cartesian coordinate system. The Attempt at a Solution I tired to solve, but...
  44. G

    Can these diagrams describe an electrostatic field in a charge free space

    Homework Statement Determine if the following diagrams may describe an electrostatic field in a charge-free space. The rectangles are the spaces under consideration. In the first four diagrams there are field lines while in the last two there are equipotential lines Homework Equations...
  45. S

    How Is the Electric Field Calculated at the Third Vertex of a Triangle?

    Homework Statement What is the electric field at the third vertex. http://tinypic.com/r/350toif/6 edit- not working actual link works = http://tinypic.com/r/350toif/6 Homework Equations E=kq/r^2 The Attempt at a Solution E1= (labeled on the diagram) = (8.99*10^9)(4)/(.02)^2 =...
  46. M

    Compute electrostatic field

    hello! "there is a high computational expense associated with calculating the local electrostatic field [in molecular modeling and simulation]" why? what is exactly the problem? thanks!
  47. P

    Selection rules electrostatic field

    Hi all , I need some help with this problem, Homework Statement A hydrogen atom, which is in its ground state |1 0 0 > , is put into a weak time-dependent external electric field, which points into the z direction: \boldsymbol{E}(t,\boldsymbol{r}) =...
  48. A

    Tangential component of ElectroStatic Field

    There is the problem which i haven't been able to understand: "Show that the tangential component of an electric field is continuous from one side of a conductor to the other" What exactly is asked and how to prove it? Thanks!
  49. QuarkCharmer

    Electrostatic Field Lab Question

    Homework Statement Based on Volts and distance, calculate the max Electric Field between lines. Homework Equations The Attempt at a Solution We basically connected a 6Vdc battery to a plate containing two conductors and use a multimeter to plot the lines of flux of the field. To find...
  50. J

    Slightly confused about potential energy in an electrostatic field

    Hi everyone, I don't know how I manage it but I've gone and confused myself about something which I was fairly confident about right before an exam... again! So here's the deal. Let's imagine two particles A and B which have charge Q and q respectively and are separated by a distance r (I...