Electrostatic Definition and 857 Threads

  1. R

    Calculating the Divergence of an Electrostatic Field at the Origin

    Homework Statement The electrostatic field of a point charge q is E=\frac{q}{4 \pi \epsilon r^3} r. Calculate the divergence of E. What happens at the origin? Homework Equations The Attempt at a Solution Well the solution is: \nabla.E= \partialEx/\partialx +...
  2. brainpushups

    How does Lord Kelvin's water drop electrostatic generator work?

    I recently made a small version of Lord Kelvin's "thunderstorm" while I was bored at school one day, and I'm still mystified as to how such a large potential gets generated. I have two hypotheses, but I haven't had a chance to test them yet and I was wondering if anybody knew how the generator...
  3. J

    Electrostatic Potential inside sphere of uniform charge.

    1. Given a sphere of uniform charge Q, radius R: Find an expression for the electrostatic potential V as a function of r for r ≤ R. Prior proof: E= Q(r)/(4πϵ0)r^2 ,for r≤R where Q(r) is the excess charge in the spherical volume of radius r 2. Relevant equation: V = Q/(4πϵ0)r 3. I tried...
  4. J

    Electrostatic Clamps Using Dielectrics

    b]1. Homework Statement [/b] Electrostatic clamps are used for holding workpieces while they are being machined, for holding silicon wafers during electron beam microfabrication, etc. They comprise an insulated conducting plate maintained at a potential of several thousand volts and covered...
  5. P

    Electrostatic charge distribution questions

    If charge distribution inside sphere is non-uniform, how is distribution on outside of sphere uniform? (Think spherical shell with point charge anywhere inside) And how can a non-uniform surface charge be still equipotential. If there was a strong enough induced charge, wouldn't the behavior...
  6. B

    Where is the Max Electrostatic field?

    Homework Statement Consider 2 charges with value q=3[\muC], situated on the xOy plane at (0;2) and (0;-2) [cm]. Obtain the coordinates on the x-axis (y=0) where the modulo of the electrostatic field is maximum. Homework Equations The Attempt at a Solution I am trying to do this but...
  7. P

    Questions about Electrostatic Fields

    I have two questions: Why is it that the field lines of the electrostatic field do stray one from the other one when abs(E) decreases? Second question: Why is abs(E) bigger in the areas where the equipotentials are squeezed up? Thank you!
  8. L

    What Causes the Negative Sign in Electrostatic Potential Energy Calculations?

    another pretty simple question that i can't see: a 1d harmonic oscillator of mass m carries an electric charge q. a weak uniform, static electric field of magnitude E is applied in the x direction. what is the classical electrostatic potential energy for a point particle at position x...
  9. Q

    Calculate the electrostatic energy of a homogeneously charged sphere

    QUESTION: Calculate the electrostatic energy of a homogeneously charged sphere of Volume V and compare the result with 2 times the electrostatic energy of a homogeneously charged sphere of V/2. SOLUTION: OK, so we have a charge Q which is uniformly distributed within a sphere of...
  10. L

    Electrostatic energy of a dielectric sphere

    1. Find the electrostatic energy of a neoprene sphere or ratio R, charged with Q if: a) Q is uniformly distributed in surface The Attempt at a Solution So, I can calculate the displacement field (so that I can use the expresion U= \int \vec{D}.\vec{E} dV), but only for those points in...
  11. H

    Electrostatic potential problem (got 1/3) correct

    Point charges q1, q2, and q3 are fixed at the vertices of an equilateral triangle whose sides are 2.50 m long. Find the electrostatic potential energy of this system of charges for the following charge values. a.)q1=q2=q3=3.90uC I got the right answer for this one 164mJ...
  12. J

    Electrostatic repulsion formula for plates

    Hey all I read somewhere online that Coulomb's Law only applies to spheres and point charges, and was wondering what formula is used to calculate the force between 2 plates whilst charged the same polarity Also, what is the formula to determine how much voltage is required to maintain a...
  13. O

    Calculating Net Charge on a Metal Sphere with Added Electrons

    Homework Statement A Metal sphere has a charge of +6uC. What is the net charge after 1*10^14 electrons have been placed on it? Homework Equations Single Electron - -1.6*10^-19 The Attempt at a Solution 1st. Convert +6uC to 1.6*10^-6 (is this right?) 2nd...
  14. K

    Help with Conductors in Electrostatic Equilibrium

    Can someone please help me with this problem. I don't even know where to begin after drawing the picture. Two identical conducting spheres each having a radius of 0.500 cm are connected by a light 1.80 m long conducting wire. A charge of 63.0 µC is placed on one of the conductors. Assume the...
  15. A

    Change of variable in electrostatic potential energy.

    Homework Statement Hello everyone i have a problem in visualizing why a a change of variable happens. To evaluate a volume integral. I hope that someone could give me a hint of the reasoning that makes you think in that specific change of variable. Homework Equations See the attachment for...
  16. A

    Electrostatic force on a charge

    i was reading the book of Griffin - introduction to electrodynamics. it is written that the force of charge q on Q is not only depends on the distance b.w them but also the velocity & acceleration of charge q.then i think coloumb'law is incomplete at all. it must include some quantity for...
  17. A

    Electrostatic Problem - finding initial separation of two particles

    Homework Statement One particle has a mass of 3.00 \times 10^{-3} kg and a charge of +8.00 \mu C. A second particle has a mass of 6.00 \times 10^{-3} kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation...
  18. L

    Electrostatic induction (can someone check my answer?)

    Homework Statement Three identical metal spheres are supported on three insulating stands.A charge q is given on the first sphere .The first sphere is then momentarily touched with the second sphere and then the second sphere is momentarily touched with the third. Finally the third sphere is...
  19. A

    Calculating Electrostatic Force with Coulomb's Law

    Four point-charges are fixed at the corners of a 3.0m X 4.0m rectangle. The coordinates of the corners and the values of the charges are listed below. q1 = 100 microC (0, 4m), q2 = 36 microC (4m, 3m), q3 = 125 microC (0, 3m) and q4 = 32 microC (0,0). Compute the net electrostatic force acting on...
  20. C

    Establishing an Electrostatic Series: My Confusion

    I'm doing an electrostatics lab and I'm getting a bit confused. The object of the lab is to establish an electrostatic series. First, I must choose a reference material, like plastic wrap. Then I charge this reference material by rubbing it in wool. Now, just by looking at any other...
  21. S

    Gauss Law and Electrostatic Field

    Homework Statement Use Gauss' law and symmetry to find electrostatic as a function of position for an infinite plane of charge. Let the charge lie in the yz-plane and denote the charge per unit area by \rho=\alpha*e^{-abs(x/b)} Homework Equations Q=triple integral of density The Attempt at...
  22. P

    Electrostatic Force: -0.7nC Charge at Origin

    Homework Statement A -0.7nC charge is located at the origin, while a 1.9nC charge is located 3.9 m away along the x-axis and a 0.8nC charge is located -1.7m away along the y-axis. The Coulomb constant is 8.98755*10^9 Nm^2/C^2. Find the magnitude of the electrostatic force on the charge at the...
  23. S

    How to Calculate Net Electrostatic Force in a Square Configuration?

    There are four charges, each with a magnitude of 1.98 μC. Two are positive and two are negative. The charges are fixed to the corners of a 0.288-m square, one to a corner, in such a way that the net force on any charge is directed toward the center of the square. Calculate the magnitude of the...
  24. G

    Electrostatic induction in a conductor

    Two aluminium plates, each 150 x 150mm, were separated by 100mm to create a form of parallel-plate capacitor. A DC voltage of 300 volts was connected across the plates to create a (fairly) linear electric field of approximately 3000 V/m between them. An insulated conductor was bent into a U...
  25. G

    Electrostatic induction in a conductor

    Two aluminium plates, each 150 x 150mm, were separated by 100mm to create a form of parallel-plate capacitor. A DC voltage of 300 volts was connected across the plates to create a (fairly) linear electric field of approximately 3000 V/m between them. An insulated conductor was bent into a U...
  26. K

    How Would Changes in Coulomb's Law Affect Electrostatic Interactions?

    Homework Statement 1)Coulomb's law states that the electric force becomes weaker with increasing distance. Suppose that instead the electric force between two charged particles were independent of distance. In this case, would a charged comb still cause a neutral insulator to become polarized...
  27. M

    Electrostatic force of attraction between two particles

    The homework problem reads as follows: A proton and an electron are held in place on the x axis. The proton is at x=-d, while the electron is at x=+d. They are released simultaneously, and the only force that affects their motions is the electrostatic force of attraction that each applies...
  28. P

    Electrostatic Field concept question

    Homework Statement A ping pong ball covered with a conducting graphite coating has a mass .005 kg and a charge -4 microC. What electric field will exactly balance the weight of the ball? Homework Equations qE = mg The Attempt at a Solution I know how to get the magnitude of the...
  29. P

    Electrostatic Constant Written Funny

    So the electrostatic constant k = 9*10^9, but I've also seen it written in my Fundamentals of Phys book (Resnick) and Wikipedia as k = 1/(4*pi*e0). Why is this? Thanks.
  30. J

    Electrostatic Force: Learn About Its Effects

    electrostatic force! Homework Statement http://img10.imageshack.us/img10/3914/picture0117.jpg Homework Equations The Attempt at a Solution
  31. D

    How can I use electrostatics to collect dust in my home?

    hi, i'm trying to find a way to attract small dust particles in a household environment to a surface. i have no physics and no engineering skills whatsoever so this is all new to me, but what i am wanting to do is have a surface with a constant charge, as perhaps this is the way to achieve this...
  32. S

    Electrostatic field ( Gauss Law )

    Homework Statement Assuming that an infinitely long line charge of 50(pC/m) parallel to the y-axis at x=2(m) and z=1(m), determine the electric intensity at the point (-1, 5, -3). The answer given : -0.18(ax0.6 + az0.8)(V/m)Homework Equations Electric field intensity due to an infinite...
  33. L

    Does Electrostatic Potential Obey Superposition?

    why does electrostatic potential obey superposition? it's a solution of poisson's equation and solutions of poisson's equation definitely do not obey superposition!
  34. N

    Coulomb's Law, net electrostatic force

    Homework Statement A particle with charge −9 μC is located on the x-axis at the point 8 cm, and a second particle with charge 5 μC is placed on the x-axis at 6 cm. The Coulomb constant is 8.9875 × 109 N · m2/C2. What is the magnitude of the total electrostatic force on a third particle with...
  35. S

    Concentric spheres and electrostatic induction

    Homework Statement There's three thick, conducting concentric spheres with radii R1, R2, R3 (R1 < R2 < R3) with charge Q1, Q2, Q3 respectively. a.- The middle one is now wired to the ground. Find its net charge b.- The internal and external spheres are now wired. Find the distribution of all...
  36. S

    Calculating Electrostatic Pressure on a Charged Sphere

    Homework Statement A sphere with radius R is charged with surface density σ. The charge found in a small surface Δs is repelled by the rest of the sphere, thus generating an electrostatic pressure. Find the pressure. Homework Equations The Attempt at a Solution I think I have to compute the...
  37. R

    Electrostatic dust distribution

    Hi, I am more familiar with the world of biology and chemistry, however I am trying to come up with a method to evenly distribute dust over a surface area which may require a bit of Physics help. I was wondering is there any way of say, positively charging an aluminium foil surface and...
  38. L

    Light in electrostatic potential

    Is electromagnetic radiation affected, in any way, by a strong electrostatic field (or gradient of field)? Specifically, is it possible to reflect light with such a field or to confine an EM wave inside an electrostatic potential well?
  39. G

    Is electrostatic just stationary electricity?

    this is short: is electrostatic just electricity that isn't moving and electricity is electricity moving? thanx :)
  40. I

    Electrostatic Filter for Computers

    I'm a senior student in high school requesting assistance and/or evaluation of a small-scale electrostatic filter for computer usage as a dust remover to prevent or mitigate build up of dust inside a computer. Isometric pictures of the main parts are available. It is basically an...
  41. LarryS

    Energy of Electrostatic Charge ?

    Does a charged particle at rest (m0>0) have more total energy than an uncharged particle with the same rest mass at rest? Thanks in advance.
  42. C

    What is the Electrostatic Potential Energy of a Charged Spherical Conductor?

    Homework Statement What is the electrostatic potential energy of an isolated spherical conductor of radius 24 cm that is charged to 3.9 kV? Homework Equations Electric potential U = (kQ)/r The Attempt at a Solution U = ((8.99 * 109 ) * (3.9 * 103)/(0.24) Could...
  43. K

    How Do You Calculate the Net Electrostatic Force on a Central Charge?

    Homework Statement A charge of -3.00 µC is fixed at the center of a compass. Two additional charges are fixed on the circle of the compass (radius = 0.125 m). The charges on the circle are -4.00 µC at the position due north and +5.00 µC at the position due east. What is the magnitude and...
  44. N

    AnswerSolving Electrostatic Force: Find Charge & Mass

    electrostatic force? Homework Statement Two very small spheres are initially neutral and separated by a distance of 0.50 m. Suppose that 6.2 x 1013 electrons are removed from one sphere and placed on the other. What is the magnitude of the electrostatic force that acts on each sphere...
  45. A

    Angular momentum in an electrostatic field

    If a charged particle is moving in an electrostatic field is angular momentum conserved? I'm thinking it's only conserved if the electrostatic potential is constant throughout space
  46. S

    Electrostatic potential and electric fields

    Homework Statement 3. Four charged particles are held fixed at the corners of a square of side s. All the charges have the same magnitude Q, but two are positive and two are negative. In Arrangement 1, shown , charges of the same sign are at opposite corners. Express...
  47. Z

    Calculating point charges and ratio of electrostatic force to weight

    Homework Statement Measurements show that a honeybee in active flight can acquire an electrostatic charge on the order of 93 pC. a)How many electrons much be transferred to produce this charge? Ne = * b) Supposing two bees, both with this charge, are separated by a distance of 12 cm...
  48. S

    Magnitude of the Net Electrostatic Force On an Oxygen Atom

    Homework Statement The water molecule forms an angle, with hydrogen atoms at the tips and the oxygen atom at the vertex (see diagram in the previous problem). Assume that the angle at the oxygen atom is Θ = 103.5o and the distance between the oxygen and the hydrogen atoms is d = 93.1 x 10-9...
  49. K

    Spring and electrostatic forces

    Homework Statement You have a lightweight spring whose unstretched length is 4.0 cm. You're curious to see if you can use this spring to measure charge. First, you attach one end of the spring to the ceiling and hang a 1.0 g mass from it. This stretches the spring to a length of 5.0 cm. You...
  50. H

    Net Electrostatic Force on a neg charge next to a pos charge inbetween a field

    Homework Statement Two point charges, Q1 = -6.9 µC and Q2 = 1.1 µC are located between two oppositely charged parallel plates, as shown in Fig. 16-65. The two charges are separated by a distance of x = 0.38 m. Assume that the electric field produced by the charged plates is uniform and equal...
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