What is Electrostatic: Definition and 879 Discussions

Electrostatics is a branch of physics that studies electric charges at rest.
Since classical physics, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, ήλεκτρον, or electron, was thus the source of the word 'electricity'. Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulomb's law.
Even though electrostatically induced forces seem to be rather weak, some electrostatic forces such as the one between an electron and a proton, that together make up a hydrogen atom, is about 36 orders of magnitude stronger than the gravitational force acting between them.
There are many examples of electrostatic phenomena, from those as simple as the attraction of the plastic wrap to one's hand after it is removed from a package to the apparently spontaneous explosion of grain silos, the damage of electronic components during manufacturing, and photocopier & laser printer operation. Electrostatics involves the buildup of charge on the surface of objects due to contact with other surfaces. Although charge exchange happens whenever any two surfaces contact and separate, the effects of charge exchange are usually only noticed when at least one of the surfaces has a high resistance to electrical flow. This is because the charges that transfer are trapped there for a time long enough for their effects to be observed. These charges then remain on the object until they either bleed off to ground or are quickly neutralized by a discharge: e.g., the familiar phenomenon of a static "shock" is caused by the neutralization of charge built up in the body from contact with insulated surfaces.

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  1. P

    I Electrostatic repulsion at a distance

    What does it mean ? "the virtual photon's plane wave is seemingly created everywhere in space at once, and destroyed all at once. Therefore, the interaction can happen no matter how far the interacting particles are from each other." As far as I know, the electrostatic force between two...
  2. iVenky

    Solving Charge Across Plates of a Capacitor w/ Negative Ions

    Homework Statement I have a material placed between parallel plates depleted of free electrons and contain negative ions. What would happen to the charge stored across the plates? Would it still be similar to placing a capacitor with a di-electric constant between them? Homework Equations Q=CV...
  3. C

    Exploring Electrostatics with Gauss Theorem

    Having come experimentally to an interesting electrostatic effect, I have returned, aged 47, to my old books in physics. It turns out that my books delight in using Gauss theorem etc. in rather ideal geometrical surface charge distribution, but never gave me the tools to answer to this simple...
  4. Kaan99

    Electrostatic self-force is zero

    Homework Statement Consider a charged body of finite size, (\rho=0 outside a bounded region V). \vec{E} is the electric field produced by the body. Suppose \vec{E} \rightarrow 0 at infinity. Show that the total self-force is zero: \int_V \rho \vec{E} dV = \vec{0}, i.e. the charged body does not...
  5. G

    Potential generated by a point charge in a isotropic medium

    Homework Statement When a point charge is positioned at the origin = 0 in an isotropic material, a separation of charge occurs around it, the Coulomb field of the point charge is screened, and the electrostatic potential takes the form \phi(r) = \frac{A}{r} \exp\left( -\frac{r}{\lambda}...
  6. 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...
  7. 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}##...
  8. Salman Ali

    How do the charges in 3 cancel each other out in net electrostatic force?

    Here is the question no1 in image. A charge is in between . We will let it possitive or negative. The answer is 3,1,2 4...But how? Won't the charges in 3 cancel each other out because they are possitive at right and negative at left. One is attracting so the other is repelling.
  9. N

    Build an Efficient Electrostatic Generator: Tips, Tricks, and Resources

    Hi all Interested in making an electrostatic generator, anyone have experience of building one and also what type would be the most efficient build induction or friction based? Lots of info on the net regarding the principles but and good books for this or websites? Also how best to...
  10. iVenky

    Electrostatic force with and without a conductor in between

    The figure shows a charge q1 exerting a force on a test charge qu. What happens to the electric force when a conductor is placed between q1 and qu (cases 1 and 2)? Does the force still remains the same? I am asking this because I am actually interested in finding what happens to the flux in...
  11. sal1234

    Electrostatic potential energy

    [Note from mentor: this was originally posted in a non-homework forum, so it does not use the homework template.] There is a general relation between the work U required to assemble a charge distribution ρ and the potential φ(r) of that distribution: U = 1/2 ∫ ρ...
  12. Javier Lopez

    A Ion Generation Troubleshooting: Overcoming Limitations in Small Ion Accelerators

    I have to increase ion generation in a small ion accelerator but I have troubles to go over 20mA (1.27e17 ions/second). I can modulate up to 40 Mhz at 1kV. What ion generator it is recommended gor large ion flux?, I can work in pulse generation.
  13. C

    Finding the potential inside a semiconductor

    Homework Statement My question is more about understanding the task itself, not about calculation. I am supposed to use the poisson equation, to derive the potential inside a semiconductor for a barrier with potential height ##\phi_B## and a donator doping with ##N1 > N2##. Then I should use...
  14. B

    Electric Field and Potential in a conductor

    So in my textbook (Introduction to Electrodynamics by Griffiths) it said that inside a conductor, the electric field E would have to zero, since if it wasn't the free charges would move accordingly and create a electric field that cancels the original field. But in a question that soon followed...
  15. G

    System of multiple conductors: image method

    Homework Statement The following figure represent the traversal cut of a system with two cylindrical equal conductors of radius r0 length l at a distance d from one another and at the same distance h of a plane conductor (conductor zero). The dielectric that surrounds the conductors is the air...
  16. D

    What is the solution for the integral of 2x?

    Homework Statement Given an E field, determine if it's a possible electrostatic field. If so, determine a potential Homework Equations ∇⋅E ∇×E The Attempt at a Solution [/B] Just more of a clarification, since my friend and I both attempted this question differently. I took the...
  17. G

    2 definitions for voltage, how are they equivalent?

    So I'm studying electrostatics and I came across to two different definitions of potential difference/voltage (because we're in stationary regimes) and I'm having trouble understanding how the expressions are equivalent. They are for a voltage between point A and point B $$U=V_a - V_b...
  18. J

    I Charged insulator with electrons throughout its volume?

    Could one make a negatively-charged insulator with the extra electrons trapped all the way through its volume by building it up layer by layer with electrons "sprayed" onto each layer as it was constructed? I guess the electrons would be trapped in empty atomic orbitals within the material - is...
  19. C

    Electrical How to maximize the efficiency of the corona discharge generator

    Hi, I have a wirmhurst electrostatic generator and I want to use it to create a corona discharge. My common sense tells me that the metal "shaft", which connects to the metal spheres should lead to significant (electron) leak, since it has a much smaller radius of curvature than said spheres. If...
  20. A

    How to solve this electrostatic potential integral equation with Python

    Hi! I would like solve this kind of relation: \phi = \int_0^r \phi (r') 4 \pi r'dr' But I don't know how to proceed... Can you advise me ? Thank's in advance !
  21. lordlarddallas

    Potetial Difference between center and point r

    Homework Statement A cylindrical conductor of length L and radius R, L » R, carries a charge Q. 1. Neglecting boundary effects; evaluate the potential difference between a point at distance r from the center of the cylinder, and the center. Assume r to be of the same order of magnitude as R but...
  22. spareine

    Electrostatic levitation of hair

    If a person with long thin hair touches a Van de Graaff generator, his hair will begin to levitate by electrostatic repulsion. The body is a conductor. Hair is an isolator, so the charge cannot flow through the shaft from root to end. To me it is unclear whether the hair is charged...
  23. F

    Plate capacitor connected to a battery (what does a battery do)

    I have a plate capacitor connected to a battery with a known potential difference. Now the plates are moved apart by dx and I must figure out the change in energy stored in the battery. Question 1: When a plate capacitor is connected to a battery charges must flow until the potential difference...
  24. G

    "long-range" and "singular" electrostatic potential?

    EDIT: Problem is FIXED. Hello, I'm trying to understand Ewald Summation and finally found a great link (http://micro.stanford.edu/mediawiki/images/4/46/Ewald_notes.pdf) that I could follow in the five first pages. But then I'm blocked by a rather odd formulation p. 5, after eq. (25): "where...
  25. zonde

    I Problem with classical electrostatic potential energy

    In classical physics electrostatic potential energy is: ##U=k_e\frac{q_1q_2}{r}## So amount of potential energy is not limited as ##r\rightarrow 0## But obviously potential energy (= binding energy) is limited by masses of charge carrying particles. Say when electron and positron annihilates...
  26. CDL

    Point Charges on a Polygon with another Charge in the Middle

    Homework Statement Suppose we have a regular n-gon with identical charges at each vertex. What force would a charge ##Q## at the centre feel? What would the force on the charge ##Q## be if one of the charges at the vertices were removed? [/B]Homework Equations Principle of Superposition, the...
  27. P

    How many electrons were transferred to create an attractive force of 1 N?

    So there was a question in a textbook that went as so: 'Two point charges (30 cm apart in air) are charged by transferring electrons from one point to another. Calculate how many electrons must be transferred so that an attractive force of 1 N exists.' It is assumed that both point charges...
  28. S

    Potential due to a charged plate using the dipole approximation

    Homework Statement A plane z=0 is charged with density, changing periodically according to the law: σ = σ° sin(αx) sin (βy) where, σ°, α and β are constants. We have to find the potential of this system of charges. Homework EquationsThe Attempt at a Solution [/B] I...
  29. Safder Aree

    How Do You Calculate the Capacitance of a Sphere Using Only Charge or Potential?

    Homework Statement Assume a conducting sphere has a radius of 3400km with an electric field of 100 V/m at it's surface. a) Calculate total charge of sphere. b)Calculate potential at the surface using infinity at reference point c) Calculate capacitance of the sphere using the result of a or b...
  30. psy

    Electrostatic Force and Field between two charges

    Two positive point charges with a charge of 10nC each are 10cm apart. What is the electric field strength at point A? How is it directed? Which force acts on a charge of 100nC at point A? F = k * q1 * q2 / r^2 E = F/q r^2 = (l1/2)^2 + (l2)^2 => r = 0,707m Electric field strength : E1 = E2 =...
  31. F

    The electrostatic potential energy of two spheres

    Homework Statement Homework Equations The Attempt at a Solution Is my answer correct ?
  32. 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...
  33. radiant_june

    Parallel plate electric fields -- # of electrons transferred

    Homework Statement An oil droplet is suspended between two horizontal parallel plates with a separation of 0.4 cm. If the potential difference of 320V is applied to the plates, determine the number of electrons transferred to/from the droplet. Given/Known Values mdroplet = 5.2×10-6 kg d = 0.4...
  34. H

    Electrostatic energy after a metal piece is inserted between 2 capacitor plates

    Homework Statement fig 1 : Area of each plate is S, separated by 2d, charge Q in the capacitors fig 2 : uncharged conductors of area S, thickness d, inserted parallel between plates What is the ratio of electrostatic energy in fig 2 to electrostatic energy in fig 1? Homework Equations Q =...
  35. radiant_june

    Electric field strength at a point between charges

    Find the electric field strength at point B between two charges shown below: Given/Known Values q1 = 4.0×10-6 C r1 = 40 cm = 0.4 m (Distance from q1 to point B) q2 = -1.0×10-6 C r2 = 30 cm = 0.3 m (Distance from q2 to point B) k = 9.0×109 Nm2/C2 Equations Electric Force: FE = (k⋅q1⋅q2)/r2...
  36. lbwet

    What's the total resistance in this circuit?

    Homework Statement https://imgur.com/3H3pCkD R is the resistance of each resistor, determine total resistance in the circuit. (see the image in the link above) Homework Equations R=1/R₁+1/R₂+1/R₃+... (in parralel circuit) R=R₁+R₂+R₃... (in series circuit)The Attempt at a Solution I'm...
  37. F

    I How can electrostatic fields be composed of photons?

    I know little about QED, QCD, and whatever the corresponding theory for the weak force is, and of course virtually nothing about the quantized theory of the gravitational force, which mostly doesn’t exist, so the following arguments and questions may be somewhat wrongly based where they refer...
  38. T

    Electrostatic force between a Half Cylinder and a Plate

    Homework Statement (This is not a HW problem, but HW-type problem.) A half cylinder of radius R and length L>>R is formed by cutting a cylindrical pipe made of an insulating material along a plane containing its axis. The rectangular base of the half cylinder is closed by a dielectric plate of...
  39. V

    Electric Field of a solid sphere of non-uniform surface density

    A solid sphere has surface charge density, Rho (r) Rho(r) = k 1 ( 0 < r < a) k2 x ( a < r < R) 2) Find the electric field in all region i.e 1) r < a and 2) a < r < R and 3 ) R < The attempted solution and the question with the diagram is attached below Could the answer be verified...
  40. S

    Growing Oxide Layers in electrostatic fields

    Can an electrostatic field be used to create an oxide layer that has a permanent electric field? For a specific example; an aluminium domed van de graaff generator with no oxide layer. If it is turned on and allowed to contact oxygen, would the oxide layer store a permanent electric field?
  41. Hammed

    Why Is the Electric Flux from a Point Charge Only Half Through the XY Plane?

    A point charge +Q is located 1 m below the x-y plane. What is the total electric flux passing through the x-y plane? I know the answer should be Q/2 but how?
  42. Hypercube

    Electrostatic Boundary Conditions

    Hello PF community, I am currently self-studying electrodynamics from Griffiths textbook, and I'm at a point where the book discusses electrostatic boundary conditions. If someone can please check if my reasoning is right. So, as I am approaching an infinite, uniformly charged plane (let the...
  43. Aastik Tripathi

    Modification in Coulomb's Law and its implications

    If the coulomb's law instead of following an inverse square relationship, follows an inverse cube relationship, How would it affect an isolated charged conducting sphere? How would it's field vary within the volume and how would the volumetric charge density be affected? Please give in some...
  44. Pushoam

    Point charge outside a grounded conducting sphere

    Homework Statement Homework EquationsThe Attempt at a Solution Option (a), because the potential is 0 on the surface, and potential due to point charge is positive so there must be negative charge on the surface. Since opposite charges attract each other, there is an attractive force...
  45. Curtis Cleary

    Find the coordinates of a charged particle given the E field

    Homework Statement The electric field in an xy plane produced by a positively chatged particle is 7.2(4x+3y)N/C at the point (3, 3)cm and 100x N/C at the poiint (2, 0)cm. Note, x and y used here are unit vectors. find the x and y co-ordinate of the charged particle what is the charge of the...
  46. C

    How does the conservation of electrostatic energy work?

    A charge of +2.5 micro coulomb is at the origin and a +3.5 micro coulomb is at the point (3,0). What is the velocity of a proton when it is at (6,0) if it was released at (5,0). My solution: $$E_0=E_f$$ $$PE=KE$$ $$Since...Work = -PE$$ I can calculate the work it takes to move the proton from...
  47. A

    Fully filled capacitors with parallel dielectrics problem

    consider that we have two dielectrics inside a capacitor as shown in the picture, let0s consider also that Q is the charge of the capacitor and d the distance between the two plates , the first dielectric occupy a surface of S/3 with a dielectric constant of er1 and the second a surface of 2S/3...
  48. Fraser MacDonald

    What is the electrostatic force field?

    I have just covered the electricity unit in my advanced higher physics course, and have happily accepted that a force is created between charged particles. I understand that coulombs law can be used to calculate this force, but here is my question. What actually is this force between the charged...
  49. S

    Electrostatic Force - Locations of a second charge

    Homework Statement A force of 2.4N [L] is exerted on a -1.8x10-6C charge 0.2m away. What are the possible charges and locations of the second charge? Homework Equations FE= kq1q2 / d2 The Attempt at a Solution Rearranging the equation above for q2 is q2 = FE x d2 / kq1 and substituting...
  50. J

    Surface bound charge on the outer surface of a dielectric

    Homework Statement With regards to a one dimensional conducting wire with a homogeneous charge density λ surrounded by a cylindrical glass dielectric of radius R, find: (a). The displacement vector inside the dielectric (b). The surface bound charges on the surface of the dielectric Sorry...
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