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. S

    Calculating Distance Between Charges Using Coulomb's Law

    Homework Statement What is the distance between two charges of -5.00 C each if the force of electrostatic repulsion acting on them is 5.00 x 10^3 N?[/B]Homework Equations Is this rearrange formula correct? r^2=k(q1q2) / F[/B] The Attempt at a Solution 6704m
  2. U

    Simple expression for Coloumb energy

    How did they arrive at this expression? I understand the ##Q^2## term in the nominator and the ##r = r_0 (A)^{\frac{1}{3}}## term in the denominator. Where did the ##\frac{\alpha}{2}## term come from? Putting in Z=40, A=100 gives ##3.3 \times 10^{14} J##, not ##65 MeV##. The energy term...
  3. R

    Electrostatic Problem at point on a conical surface

    Homework Statement I am trying to understand a solved problem which is about finding electrostatic potential at point b of the following conical surface with a given surface charge: I have attached the worked solutions to this post. In the solutions, I don't understand how they have got the...
  4. H

    Determine the total electrostatic potential energy

    Homework Statement Determine the total electrostatic potential energy of a nonconducting sphere of radius r_0 carrying a total charge Q distributed uniformly thorughout its volume. Homework Equations U = qV The Attempt at a Solution \rho = \frac{Q}{4/3\pi r_0^3} = \frac{dq}{4\pi r^2dr}...
  5. 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...
  6. Emily_20

    Calculating Electrostatic Force Between Pennies with Slight Charge Differences

    Homework Statement We know that the magnitudes of the negative charge on the electron and the positive charge on the proton are equal. Suppose, however, that these magnitudes differed from each other by as little as 0.0001%. With what force would two copper pennies, placed 1.0 m apart, repel...
  7. throneoo

    Total Electrostatic Energy in a system of charges

    Suppose there are N charges fixed at arbitrary locations , how do I calculate the total electrostatic energy ? I can think of two ways. one being the straightforward coulomb's law : k=1/(4*pi*ε) Q=k/2 * ΣiΣj qiqj / |ri-rj| ; i≠j the other method is to integrate energy density with respect...
  8. S

    Why does electrostatic force move water but not magnetism?

    So I was surprised to notice that my plastic shopping bag was able to actually push and pull tap water significantly far with its electrostatic force. But when I put a magnet near the water nothing happened. What makes the electrostatic force so different from magnetic force; isn't it just two...
  9. L

    What is the electrostatic force on the Y charge?

    First off idk if this is the right topic to post in but I've been at this problem for hours and I have no idea how to solve it. Three metal spheres are situated in positions forming and equlateral triangle with sides of 0.012 m. X has a charge of -2.5 C. Y has a charge of 3.00 C. Z has a charge...
  10. D

    Understanding Electrostatic Charges: A Short Quiz

    Homework Statement Select the answers which complete the statements below (e.g., if answer A completes the first statement, and answer B the others, enter ABBBB).A) positive B) negative C) neutral D) cannot tell A positive point charge is brought near the outside surface of a neutral...
  11. A

    Alternative electrostatic potential

    Homework Statement Assume that the electrostatic potential of a point charge ##Q## is $$ \Phi(r) = \frac{1}{4\pi\epsilon_0}\frac{Q}{r^{1+\delta}},$$ such that ##\delta \ll 1##. (a) Determine ##\Phi(r)## at any point inside and outside a spherical shell of radius ##R## with a uniform surface...
  12. A

    Electrostatic induction in different size spheres

    if we have a charged sphere with charge Q and radius r, the voltage on it's surface is calculated by gauss's law, what if we approach to it another sphere with radius R , R>r, Earth it, remove earth, basically charging by induction, will the sphere have the same charge, which means less voltage...
  13. J

    Why does my hand create a static discharge when I touch a metal object?

    Dear all, I would like to ask you to explain me this question on physical (chemical) level. Question is: Why static electrical charge is moving when I press and move my hand on rug and then catch a piece of iron, which is not gorunded? According to my knowledge, iron atoms had not strong...
  14. Arjang Sh

    Can I Control Electrostatic Levitation with a Power Supply?

    Hello I need some advice about electrostatic levitation concept and am trying to make an experimental setup for that. Consider two parallel plates with the same sign charge and the bottom plate is fixed in place. Therefore there will be a repulsive force which pushes the upper plate...
  15. C

    Electrostatic Precipitator to Contain Graphite Powder

    Hi all! This is my first post here and I really hope you guys can help! I am currently in senior design at Purdue Fort Wayne in the MET department. I also own a company called Graphite Customs where we make graphite molds for glass blowers. When machining graphite, the powder is very abrasive...
  16. Arjang Sh

    Electrostatic repulsive force between parallel plates

    Hi I was thinking about two parallel plates with same charges (there's no electrical field between them). How can we calculate the repulsive force? Does anyone have any ideas besides numerical integration? Thanks
  17. arpon

    Problem on electrostatic force

    Homework Statement A metal sphere of radius R and total charge Q is cut into two equal halves. Find the force that is necessary to hold the two parts together. Homework Equations ##F = \frac{1}{4\pi \epsilon _0} \cdot \frac {q_1 q_2}{r^2}## ##\oint \vec E \cdot d \vec A = \frac{q}{\epsilon...
  18. L

    Electrostatic potential energy of a cubical configuration

    Homework Statement Find the Electrostatic potential energy of a cubical configuration of point charges as shown in the figure. Each of the charges is 5.00e and the edge of the cube is 2 cm. (The image is simply a cube with one of the points labeled q) Homework Equations U=kQq/r The Attempt at...
  19. M

    Hai Calculating Net Electrostatic Force Need help :(

    Homework Statement Three charged objects are placed as shown. Find the net force on the object with the charge of -5uC Diagram:[/B] http://imgur.com/xHGHGbd Homework Equations No idea what to do as far as steps go, I don't know how to start :([/B]The Attempt at a Solution None so far.
  20. @

    Electrostatic shielding in a cavity

    Suppose a constant electric field exists in space as shown in the file and a open lid cube type conductor is brought inside the field. What would be the electric field in the question marked area. Would it be zero or equal to original electric field.
  21. M

    Electrostatic equilibrium, deflection of a cobweb

    Homework Statement Homework Equations After creating a FBD and analyzing the forces, I get the equation for the angle as ## tan \theta = \frac{k q^2}{m g r^2} ## The Attempt at a Solution [/B] I have tried to find a way to find the distance between the charges ## r ##, but the only way I...
  22. AwesomeTrains

    Electrostatic Self-Energy of a uniform charged sphere

    Homework Statement Hello, I have to calculate the self-energy of an uniform charged electron with radius R. The distributed charge is e. Homework Equations The SE is given as: E=\frac{1}{2}\int dV \int dV' \frac {\rho(\vec r)\rho(\vec r')}{ |\vec r - \vec r'|} according to the problem sheet...
  23. P

    Finding electrostatic potential from charge distribution

    Homework Statement Question Homework Equations Equation The Attempt at a Solution Attempt I am not sure how to write the |r-r'| in a way that allows me to actually solve the integral. I have tried writing |r-r'| in spherical co ords, but all I seem to be able to get is this as the separation...
  24. H

    Solving Electrostatic Potential of a Spherical Conducting Shell

    Homework Statement A spherical conducting shell of radius R is held at a potential V0. Outside the shell, the charge density is ρ(r) = ρ0sinθcosφ for R < r < 2R. Find the electrostatic potential everywhere outside the shell. Homework Equations Green's function in spherical coordinates between...
  25. F

    Electrostatic Potential in Dielectric Medium

    Homework Statement I need to find the green function for a dielectric sphere (\epsilon_1) inside another dielectric medium (\epsilon_2) using the method of images. Homework Equations In gaussian units I have: \phi=\frac{q}{\epsilon|r-r1|} The Attempt at a Solution Due to the symmetry of the...
  26. S

    Looking for Information on Electrostatic Precipitators?

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  27. G

    Find the total electrostatic energy stored in the configuration

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  28. G

    Finding electrostatic potential

    Homework Statement Find the energy stored in a solid sphere by integrating ##\frac{\epsilon_0}{2} \int E^2d^3r## given that ##E=k\frac{r^2}{4 \epsilon_0}## for ##0<r\le R## and ##E=k\frac{R^4}{4r^2 \epsilon_0}## for ##r>R## Homework Equations ##U=\frac{\epsilon_0}{2} \int E^2d^3r##The Attempt...
  29. H

    Electrostatic Potential Energy with Constant Electric Field vs NonConstant Field

    When determining potential energy we have the relationship: PE = V*q = E*q*d But depending on the scenario we can't use them interchangeable right? If you want to calculate the work needed to be done by a particle going from a distance Y to right next to another particle of the same charge...
  30. A

    Electrostatic Potential in a Box

    Homework Statement A box shaped rectangular metal cavity of sides a, b and c along the x, y and z axes, respectively, has one corner at the origin. Of the six sides, all are grounded except the one at x=a and the one at y=b which are held at potentials of V1 and V2 , respectively. Find the...
  31. W

    Electrostatic interaction energy between a charge rod and ring.

    Homework Statement Thin rod of the length l is placed with one of its ends placed at the center Oof the thin ring of radius R as shown, perpendicular to the plane of the ring. Rod is charged with total charge Q that is distributed along the rod’s length with the linear charge density...
  32. S

    Electrostatic Induction: Conductor vs. Dielectric Response Time

    Do electrostatic fields induce charges on conductor surfaces faster than dielectrics respond to an identical field?
  33. H

    Electrostatic forces and distance when considering changes in potentia

    Question: Relevant formulas: kei + pei = kef + pef U = kqq/r Attempt at solution: I thought that as distance increases potential energy would go down and so that energy would have to go to the kinetic energy of the gasses, so kinetic energy would increase. This is consistent with the...
  34. W

    Does an electron with negative electrostatic potential energy fall up?

    In a vacuum under standard gravity, an anchored spherical metal electrode is brought to +1,000,000 volts relative to the distant walls of a much larger chamber. (I'm a new user; hopefully this will display as attachment 1) Therefore, electrons that fall through a small gap in the electrode...
  35. O

    Electrostatic Equilibrium Problem

    Electrostatics Equilibrium Problem-It is required to hold four equal point charges +q each in equilibrium at the corners of a square. Find the point charge that will do this if kept at the center of the square? I am doing the basics of coulomb's law,can anyone explain this to me? I cannot do...
  36. A

    Electrostatic voltage and current

    If we had a van de graaff generator, near the sphere there is a metal plate ( not touching) and it's wired to the ground (a resistor is connected to the wire) , as the voltage on the surface of the sphere increases, the voltage at the plate does too, creating a potential difference between...
  37. M

    Electrostatic Force/Coulomb's Law

    Homework Statement Homework Equations F=qE The Attempt at a Solution So in solving the problem, parts a) and b) were rather easy, and I believed part c) would be easy as well. I assumed: F=10156*(1.6E-19) which came out to 1.63E-15, but that was apparently incorrect and I'm...
  38. J

    The process in Electrostatic Precipitator

    Hi all, Can anyone describe for me the detailed the process in the electrostatic precipitator? Like once the voltage is on, how the dusts react? Would ionization happen? Is there any existing mathematical modeling for describing the process? thanks. J
  39. A

    Electrostatic shielding and capacitors

    First before asking the original question i need to make sure some of my concepts are correct: 1- what happens when a capacitor with its 2 plates having different areas is charged? according to this forum https://van.physics.illinois.edu/qa/listing.php?id=23409 as the long as the difference in...
  40. E

    Electrostatic induction - rod and sphere

    Homework Statement Hi all, need a little help on an electrostatic induction problem. A positively charged metal rod is brought near to a neutral metal sphere. What is the charge of the metal sphere and the rod when the positively charged rod touches the neutral sphere. Homework Equations...
  41. A

    Electrostatic discharge and metal rods

    I uploaded a photo to help explain the question, basically the blue rod is a -ve charged rod ( high voltage) gray one is metal and the brown is also metal but it's grounded , if gap A and B are filled with air , the high voltage will break down the air in both gaps and make 2 sparks in both gaps...
  42. D

    Electrostatic charge or dieletric field?

    Hi, I have a question on a quote I saw from Steinmetz regarding the two components of eletric field (magnetic and dielectric) To quote, ''Unfortunately, to a large extent in dealing with dielectric fields the prehistoric conception of the electro- static charge (electron) on the conductor...
  43. RJLiberator

    Nuclear charge from a potential electrostatic energy

    Question: "Given an electrostatic potential energy of -6.16x10^-18 J and a distance of 1.12x10^-10m, what is the nuclear charge if there is a single electron interacting with the nucleus?" Okay, Equation: PE = [K*Q1*Q2]/d Where K is a constant of 8.99*10^9 J*m/c d is giving at 1.12*10^-10m PE...
  44. C

    Relevance of electrostatic precipitation technology

    Hello. Is electrostatic precipitation technology relevant nowadays? Is it worth making candidate dissertation on it? I am going to investigate back-corona discharge in ESP and operation of ESP under hight inlet dust loadings by means of mathematical modelling (Comsol, my own programs if it's...
  45. E

    How can I prevent breakdown in my electrostatic generator's output wires?

    I'd like to create a high-voltage, low current source having multiple output wires each capable of attracting tiny pieces of paper. What kind of solutions should I look into?
  46. HeavyMetal

    Electrostatic attraction between an electron and a hole

    The exciton is defined as a bound state of an electron and an electron hole. From what I've read, this state is described by Coulomb's law. Coulomb's law describes the interaction between two charged particles. So my question is: because an electron hole is not an actual particle, how does an...
  47. D

    Electrostatic Precipitator Design

    I currently live in Mongolia, and during the winter months (6 months of the year) we heat our "Gers" see below picture, using coal. These are burned in stoves, and then the smoke is funnelled through a 11cm tube (chimney) through the roof. However this is very smoky and nasty, and bad for...
  48. PhysicoRaj

    Electrostatic force in a medium of non uniform permittivity

    Homework Statement Two point charges, +4 μC and -10 μC are placed 10 cm apart in air. A dielectric slab of large area and thickness 5 cm is placed between the charges. Find the force of attraction between the charges, if the dielectric has a dielectric constant of 9. Homework Equations...
  49. F

    Electrostatic boundary value problem with radial dielectrics

    Homework Statement A unit sphere at the origin contains no free charge or conductors in its interior or on its boundary. It is, however, embedded in a dielectric medium. The dielectric is linear, but the permitivity varies by angle about the origin. It is constant along any radial direction...
  50. KiNGGeexD

    Electrostatic potential of a circular ring

    I'm a little stumped with this problem, I have posted a photograph below as there is a diagram to compliment the questionExpressions which I used where V(r)= k q/r Where q= σ da Where da is an element of area And k= 1/4πεI messed around with these expressions for a while but it didn't really...
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