Charge density Definition and 419 Threads

Homework Statement A nonconducting wall carries a uniform charge density of 13.62 μC/cm2. What is the electric field 5.7 cm in front of the wall? Answer in units of N/C. Homework Equations Gauss's law...? The Attempt at a Solution Honestly, this bugger's got me scratching my...

Alright, I'm working on an idea for a MHD generator, and I have a water based solution. That is Cl- 6250 mg/L or 176 mmol/L SO4^2- 6250 mg/L or 65 mmol/L Na+ 6250 mg/L or 272 mmol/L K+ 6250 mg/L or 160 mmol/L Ca^2+ 5000 mg/L or 125 mmol/L If I'm doing my math right, that means my...

Problem: Consider a long charged straight wire that lies fixed and a particle of charge +2e and mass 6.70E-27 kg. When the particle is at a distance 1.91 cm from the wire it has a speed 2.80E+5 m/s, going away from the wire. When it is at a new distance of 4.01 cm, its speed is 3.20E+6 m/s...

Couple of electricity questions here. 4. (a) Show that in a steady state, any isotropic material that obeys Ohm’s Law contains no regions with net charge. (b) In certain types of anisotropic materials, the conductivity  is not a scalar but instead a tensor that can be represented as a...

Homework Statement (a) A charge of -345e is uniformly distributed along a circular arc of radius 4.00 cm, which subtends an angle of 41°. What is the linear charge density along the arc? (b) A charge of -345e is uniformly distributed over one face of a circular disk of radius 1.90 cm...

I need help with the electric field of a line of charge, a ring, semicircle, a line of charge at a point that bisects the line of charge, and a uniform disc. The teacher showed us how to derive those equations but he does it so fast that I didn't have time to copy them down. Even if I did I...

Homework Statement Test the convergence of the series for the surface charge density: \sum^{\infty}_{s=0}(-1)^s(4s+3)\frac{(2 s -1)!}{(2s)!} Homework Equations (2s-1)! = \frac{(2s)!}{2^s s!}; (2s)! = 2^s s! Stirling's asymptotic formula for the factorials: s! = \sqrt{2 \pi s}s^s...

1. This is a 2D Laplace eqn problem. A semi-infinite strip of width a has a conductor held at potential V(0,a) = V_0 at one end and grounded conductors at y=0 and y=a. Find the induced surface charge \sigma (y) on the conductor at x=0. 2. Homework Equations . The potential is...

Homework Statement I didn't know how to display a lot of the symbols, so I wrote the problem out in microsoft word, took a screenshot, uploaded it to photobucket, and linked it. Basically, I have to find the charge density as a function of r given the electrostatic field in the image. Any...

Hi, if we only have an electrostatic potential given. How to calculate the charge density? I know of course Maxwell equation, here without any time dependence, but I missed always some further specifications, or I forget something important :confused: :redface: thanks greetings

Homework Statement A slab of insulating material has a nonuniform volume charge density given by rho = Cx2, where C is a positive constant and x is measured from the slab’s center. The slab is infi…nite in the y and z directions. (a) Find the electric fi…eld for |x| > d=2, that is, in the...

Homework Statement The electric field strength just above one face of a copper penny is 2310 N/C. What is the surface charge density on this face of the penny? Homework Equations Surface Charge Density = Q/A The Attempt at a Solution The only thing that I can understand is that surface...

Homework Statement Given long cylinder of radius 0.2m lies along the z-axis and carries a uniform surface charge density if 10m C/m2. Calculate the flux passing through a window at (rho) = 2m, pie/4 <= (phi) <= 3pie/4 , 2<=z<=4.Homework Equations The Attempt at a Solution not sure where to start..

Homework Statement an electron with mass m = 9.11 x 10^-31 is released at rest near a very large positively charged non-conducting charged sheet lying horizontally. What should the surface charge density on this sheet be to keep the electron balanced at rest above the ground? Is it above or...

At a point where there's surface charge density sigma, by what amount is the electric field for a spherical shell of charge discontinuous? I thought about using E = 2*pi*k*sigma (although isn't that just true for a charged disc?)

Ok, the question asks: An electron close to a large, flat sheet of charge is repelled from the sheet with a 2.1×10^−12 {N} force. Q. find the surface charge density on the sheet in C/m^2 What i did was use the formula F = qe with 2.1e-12 for the force and 6.1e-19 for the charge of an...

If given variables A, d, V, and constant 8.854e-12. How can I find the magnitude of surface charge density. I originally used Sigma = Q/A but I am not getting the right answer. Any help is appreciated! :)

Alright guys I am looking for some help with this problem regarding calculating total electric charge in a layer of ions. This layer of ions is bounded between the planes x+2y+2z=4 and x+3y+3z=3, and by the 3 co-ordinate planes. The density of the ions is rises linearly from zero at the outer...

In one dimensional electron gas in charge density wave phase, as I know , the density of electrons will be periodic. The order parameter of charge density wave is written as O_{CDW}(x)=\sum_s\psi_{L,s}^{\dagger}(x)\psi_{R,s}(x) For Luttinger model, the \psi is the Fermion annihilation field...

Homework Statement Two planes of charge with no thickness, A and B, are parallel and vertical. The electric field in region 1 to the left of plane A has magnitude 3σ/(2*ε0) and points to the left. The electric field in the region to the right of B has magnitude 3σ/(2*ε0) and points to the...

Homework Statement A charge of uniform linear density 2.80 nC/m is distributed along a long, thin, nonconducting rod. The rod is coaxial with a long conducting cylindrical shell (inner radius = 5.20 cm, outer radius = 10.8 cm). The net charge on the shell is zero. (a) What is the magnitude...

Homework Statement Find the total charge inside the volume indicated: \rho_v=10z^2\rho^{-0.1x}\sin(y\pi) for -1\leq x\leq 2,0\leq y\leq 1,3\leq z \leq3.6 I know I have to integrate over the volume [tex]dxdydz[tex], but [tex]\rho^{-.1x}[tex] just keeps giving me a problem. Is there a...

Homework Statement A line of charge starts at x=+x_0 and extends to positive infinity. If the linear charge density is \lambda=\frac{\lambda_0x_0}{x}, determine the electric field at the origin. The Attempt at a Solution I'm really not sire which equations I would have to use to solve...

I've been searching for an acceptable value for the charge density of indium arsenide; that is, the amount of charge per cubic meter. I have been unable to find anything. I'm working on a replication of the Hall Effect, and I need an accepted value for comparing my own results. I've searched...

Homework Statement A parallel plate capacitor with A=125 cm2 and d=1.25 mm is charged to a potential difference of 10.0 V. What is the charge density on each plate? Homework Equations V = \frac{{\sigma d}}{{\varepsilon _0 }}\,\,\,\, \Rightarrow \,\,\,\,V\varepsilon _0 = \sigma...

[SOLVED] Electric Potential Homework Statement 20. [1pt] A 30.6- cm-diameter conducting sphere is charged to 538 V relative to V = 0 at r =infinity. What is the surface charge density sigma? Correct, computer gets: 3.11E-08 C/m^2 = Sigma, r=.153 21. [1pt] At what distance will the potential...

Homework Statement Let E(r) represent the electric field due to the charged ball throughout all of space. Which of the following statements about the electric field are true? - E(0) = 0 - E(Rb) = 0 - lim(r -->infin.)E(r) = 0 - The maximum electric field occurs when r = 0. -...

[SOLVED] Electric Field and Charge Density Oops, nevermind I guess I just use div(E) = rho/e0 Homework Statement A layer of charge fills the space between x = -a and x = a. The layer has a charge density \rho (x). The electric field intensity everywhere inside the charge distribution is...

A 10.0g piece of styrofoam carries a net charge of -.700 x 10^-6 C and floats above the center of a large horizontal sheet of plastic that has a uniform charge density on its surface. What is the charge per unit area on the plastic sheet? I've been trying to think a way to model this with a...

I have a line charge of length L and charge density /lambda on the Z-axis. I need to express the charge density in terms of the Dirac Delta function of theta and phi. How would I go about doing this?

Homework Statement Find an expression for the electrostatic self-energy of an arbitrary spherically symmetric charge density distribution p(r). You may not assume that p(r) represents any point charge, or that it is constant, or that it is piecewise constant, or that it does or does not cut...

Homework Statement We have a non uniform line charge density P_{l} = \rho_{l} cos\phi It is a spiral line where 0 \leq \phi \leq 4 \pi It is on the x-y plane with z=0. r varies: r ( \phi ) = \phi * r_{0} + a We need to find the Potential and Electric Field at the origin...

Could someone please answer the folloing questions. 1- What do we mean by charge density and what is its relationships with the charge and mass of a particle.??

Please tell me if by gauss law total electric field inide a solid conductor is zero... how can uniform charge density exists... Will there be any electric field inside a charged conductor ? or will it be always zero.

You have a summer intern position at a laboratory that uses a high-speed proton beam. The protons exit the machine at a speed of 2.10 times 10^6 m/s, and you've been asked to design a device to stop the protons safely. You know that protons will embed themselves in a metal target, but protons...

Homework Statement A long, straight wire has a linear charge density of magnitude 3.6nC/m. The wire is to be enclosed by a thin, no-conducting cylinder of ouside radius 1.5cm, coaxil witht he wire. The cylinder is to have positive charge on its outside surface with a surface charge density...

In the air over a particular region, at an altitude of 500 m above the ground, the electric field is 150 N/C directed downward. At 600 m above the ground, the electric field is 100 N/C downward. What is the average volume charge density in the layer of air between these two elevations? charge...

A 8.2 g piece of Styrofoam carries a net charge of -0.700 µC and floats above the center of a large horizontal sheet of plastic that has a uniform charge density on its surface. What is the charge per unit area on the plastic sheet? Ive solved some other related questions with charge...

Never mind, i got it, whew Homework Statement http://img137.imageshack.us/img137/6250/chargqg0.th.jpg The rod has a nonuniform charge density lambda = ax (a is a positive constant). Find electric potential at point A. Homework Equations V = kq/r E = kqq/r^2 V = - \[ \int_a^b E dot dr\] The...

This should be easy, but for some odd reason I am not getting the right answer. Assuming the potential V=0 at infinity, what is the V at the center of a sphere with volume charge density rho(r) = rho_0 * R/r I keep getting (integral from 0 to R K*(4*pi*rho_0)*R/2) which I don't think is...

Hi, i'm Having a bit of trouble with this challenge problem posed to us: Homework Statement A spherical cloud of charge of radius R contains a total charge of +Q with a nonuniform volume charge density that varies according to the equation: \rho(r) = \rho_{0}(1- \frac{r}{R})...

Charge Density and Neuronal Cells--Help! The cell membrane if a typical nerve cell consists of an inner and outer wall separated by a distance of 0.10 µm. The electric field within the cell membrane is 7.0 x 105 N/C. Approximating the cell membrane as a parallel plate capacitor, determine the...

Hi, I was just wondering if anyone knew if there was a table that listed the maximum charge density different materials can accomidate... Thanks in advanced, - WiredGuy

https://www.physicsforums.com/attachment.php?attachmentid=8198&stc=1&d=1162609042 V – Electric potential I drew the picture of basically a rod with end points a and –a on the x-axis with a point b that sits as well on the x positive axis. Assuming that is correct, I then am asked to find...

Here's the question: A square plate of copper with 50.6 cm sides has no net charge and is placed in a region of uniform electric field of 80.9 kN/C directed perpendicularly to the plate. a. Calculate the charge density of each face of the plate. b. Calculate the total charge on each...

Question: The electric field on the surface of an irregularly shaped conductor varies from 56.0 kN/c to 28.0kN/c. calculate the local surface charge density at the point on the surface where the radius of curvature of the surface is (a) greatest and (b) smallest. I am stuck as far as how to...

I have two problems that I need help working on. The first one is An electron is released from rest 2.0 cm from an infinite charged plane. It accelerates toward the plane and collides with a speed of 1.0 x 10^7 m/s. What is the surface charge density of the plane? The second problem is: A...

In chapter 10 section 3 volume 2 of the Feynman lectures on physics, there is a passage that I can't force myself to agree with. He says, talking about the polarization vector of dielectrics, Can someone explain this perhaps differently? I really don't see how a non-uniform polarisation...

Oh since this got moved: It's not for any course or class so I'm not following any book. I'm not sure if anyone will be able to answer this but I'll ask anyway: I've solved laplaces equation in cyclindrical coordinates for a disc of radius 'a' and constant potential V on the disk (disc in z=0...

First I want to say thanks in advance - I found this site through Google and am thrilled! All I have left to graduate is Physics II (Electromagnetism & Waves), so I'll finally be walking on August 5. IF I can pass this class, that is. I'm a non-traditional student, and it's been about 10...