Point charge Definition and 363 Threads

Not sure if this should be in quantum section, please move if necessary. We know that: 1. A stationary particle with charge q is not affected by an external magnetic field. We can assume this particle is not magnetic at all, since it would allign and travel in relation to the magnetic...

Electric field near charged sheet is sigma/2E Which is independent of the distance from it.. However In case of point charge, as we go very close to it, magnitude of electric field tends to infinity.. But why doesn't this happen with charged sheet, i mean it can also be considered as...

1. Find the work required to move a point charge from infinitely far away to the center of a thin ring. The point charge is q= 1nanocoulomb. The rings charge is Q= 2 nanoC. The ring has a radius r=2m.Homework Equations U= qV W= -U Thoughts I think the first thing to consider is the field E...

Homework Statement A cube of side a is filled with a uniform charge density distribution of total charge Q. A point charge +Q is placed at the center of the cube. Show all odd electrostatic multipole moments vanish. (i.e., 2^l poles with odd l). Show that among the even moments, those...

Homework Statement Attached Homework Equations Gauss' Law The Attempt at a Solution \epsilon_{0} E(4\pi r^{2}) = q_{enc} = -1.738x10^{-19}

Homework Statement A point charge q1 = -9.7 μC is located at the center of a thick conducting shell of inner radius a = 2.3 cm and outer radius b = 4.5 cm, The conducting shell has a net charge of q2 = 1.4 μC. 1) What is Ex(P), the value of the x-component of the electric field at...

a)Point charge Q = +7.25 μC is fixed at the origin. Point charge q = +1.60 μC is now carefully placed on the positive y-axis, and it floats at (0,7.88). Find the mass of q. b) Refer to question a. Suppose that, as charge q is floating, the point charge Q at the origin begins to lose its...

Consider a current loop with a switch and an AC source in space, there is a point charge(electron) inside this loop, my question is, Will the point charge feel any force when we close the switch, i.e. will the point charge feel any force in the presence of changing magnetic field ? If yes...

is it possible to construct a system with only finite number of point charges of arbitrary magnitude at finite distance from each other such that the total potential energy is zero everywhere? i doubt earnshaw's theorem would prohibit this construction, hence is it possible? thanks

Homework Statement In lab we did an experiment where there was a 12v D.C. power supply in a glass dish filled with water. We set the + and - terminals in the dish and a piece of graph paper underneath. With a volt-meter we hunted for certain electric potentials such as 2V, 4V, 0V, etc and wrote...

Homework Statement A +30μC charge is placed 32cm from an identical charge. How much work would be required to move a +0.50μC test charge from a point midway between them to a point 10cm closer to one of the charges. Homework Equations W = qV V = kQ/r The Attempt at a Solution...

Homework Statement Three charges are located in the x-y plane (see plot below), with Q1 = -6.00 μC, Q2 = 5.00 μC and Q3 = -3.00 μC. Note that the charges are located at grid intersections points. *I couldn't put the grid on here, but the points are Q1 = (-2,-4), Q2 = (-2, 2). and Q3 = (3...

Homework Statement A +15μC point charge Q1 is at a distance of 30mm from -30μC charge Q2. Show that the electric potential is zero at a point between the two charges which is 10mm from Q1 and 20mm from Q2. The Attempt at a Solution I know that V = Ed (where V = electric potential, E =...

While studying electricity we always take point charges to calculate force between them according to coulomb's law.And to calculate the electric field around a point charge we take a test charge which is small. My question is: 1.What is the definition of point charge and test charge...

The fields of a moving point charge can be constructed from the Lienard-Wiechert potentials. However could one not just consider a point charge at rest in a frame S' and transform the relevant quantities such as A^{\mu} back to S and then deduce the fields from here. Should not the the two...

Homework Statement Find the attractive force between a neturally charged metal ball of radius r and a point charge q, located a distance l from the center of the ball. Also find the work needed to move the charge to infinity. The ball is not grounded. Homework Equations - The...

If a point charge is placed in a cavity of a conducting sphere, and the sphere itself is given a charge , would the point charge in the cavity experience a force?

Question A point charge q_{1}=15\muF is held fixed in space. From a horizontal distance of 4.00cm , a small sphere with mass 4.00\times10^{-3}kg and charge q_{2}=2.00\muF is fired toward the fixed charge with an initial speed of 43.0m/s. Gravity can be neglected. What is the acceleration...

Homework Statement A rod of length L and total charge Q is a distance D from a point charge q which lies along the perpendicular bisector of the rod. Find the force of the rod on the point charge Homework Equations E = ∫ dE dq = λdx F = qE The Attempt at a Solution I'm...

Homework Statement Find the electric field produced by a 2.5uC point charge at distance of 0.75m. E = ___ V/m2. Homework Equations E = kq/r^2 3. The Attempt at a Solution E = (9x10^9 Nm^2/C^2)(25)/(0.75)^2 = 400 x 10^9 V/m What do you guys think? Thanks in advance!

Homework Statement A solid insulating cone has a uniform charge density of rho and a total charge of Q. The base of teh cone had a radius of R and a height of h. We wish to find the electric force on a point charge of q' at point A, located at the tip of the cone. (Hint: You may use the...

Homework Statement Two equal point charges of magnitude 4.0 μC are situated along the x-axis at x1=-2.0m and x2= 2.0m. What is the electric potential at the origin of the xy coordinate system? Homework Equations ΔV= Kc (q/r) The Attempt at a Solution Do voltages cancel each...

I have attached a diagram. s Three charge are at corners of an triangle. The + and - 5.00*10^-6C charges form a dipole. a) Find the magnitude and direction of the force exerted on the dipole from the -10*10^-6C charge. b) For an axis perepndiculat to the line connected the + and -...

Homework Statement A point charge of q1=3.6nC is moving with speed 4.5 x 107m/s parallel to the y-axis along the line x=3m. The magnetic field produced by this charge at the origin when it is at the point x=3m, y=4m is approximately: Homework Equations vector B= (magnetic constant/4pi)...

I need help understanding how to calculate various Electric Field Strengths of several point charges (Q) both inside and along two OVERLAPPING identical spheres BUT with on NON-UNIFORM VOLUME CHARGE DENSITIES (-1p non-overlap density on the outside with -4p density overlapping internally) with...

Question: A point charge is moving with speed 2 x 107m/s along the x axis. At t=0, the charge is at x= 0m and the magnitude of the field at x=4m is B0. The magnitude of the magnetic field at x= 4m when t= 0.1μs is:The equation and my attempt at solving it is in the attachment. --I also converted...

Homework Statement Calculate the surface charge density on a thin insulated and uncharged cone, which has a point charge inside of it on the cone axis. Furthermore, calculate the force between the point charge and the cone. Homework Equations The relevant equation is the Poisson equation...

Imagine an uncharged spherical conductor centered at the origin has a hole of some strange shape carved out inside it, and a charge q is placed somewhere within this hole. What is the field outside the sphere? Is it even possible to determine the electric field simply from the given...

Homework Statement Give an expression to find V of Arc of uniform charge (at the center, or origin) Homework Equations V=kQ/R The Attempt at a Solution the solution is kQ/R. I'm wondering why an arc can be treated like a point charge... Is this reason partly connected to a...

I am not sure why or how the distance away from a charged conductor, r, is greater than the radius of that charged conductor or surface, R, then the electric field is that of a point charge.. if r>>R then we are far from conductor. if r<<R then we are close to the conductor.. these are...

Homework Statement Three charges are placed along a meter stick. One charge, q1, is placed at the 12.1cm mark. A second charge, q2, is placed at the 27.2cm mark. The third charge, q3, is placed at the 48.5cm mark. Charge q1 is equal to +171μC. What must be the sign and magnitude of charge q3...

Homework Statement Write down a general function where E=f(r,D) for sphere (D=3), (where D is a dimensionality parameter, which describes how many orthogonal directions x,y,z the field drops off from its maximum). Homework Equations The Attempt at a Solution E=f(r,3) Am I...

Point P in the figure is equidistant from two point charges +Q/-Q of equal magnitude. If a negative point charge is placed at P without moving the original charges, the net electrical force the charges +Q/-Q will exert on it is? figure: http://goo.gl/EAADC ATTEMPT: i think P will move...

I had a question (very similar to this) for homework a few days ago, which was basically: In which arrangement will the electric field at the leftmost point be largest and in which will it be the smallest? A. (+)-------(+) B. --------(+)-------(+) or C. ----(+)---(+)...

Hi everyone, Consider two frames: the rest frame that has a stationary point charge and the moving frame which has a moving point charge. In the rest frame the point charge has electric field lines pointing radically outward. The charge can be imagined to be surrounded by a spherical shell...

Homework Statement My problem is the following:There is a point charge inside a thin uncharged and insulated metal cone. Calculate the charge distribution on the cone and the force between the point charge and the cone. I presume "thin cone" means only the infinitely narrow surface of a...

My problem is the following:There is a point charge inside a thin uncharged and insulated metal cone. Calculate the charge distribution on the cone and the force between the point charge and the cone. I presume "thin cone" means only the infinitely narrow surface of a cone.The relevant equation...

Not much more to add to the title. I was just wondering, under what conditions can a charged sphere be treated as a point charge?

Relationship between Electric Fields and Distance from point charge?? Homework Statement Homework Equations E= kq/r^2 The Attempt at a Solution K so looking at the graph, I noticed that there is a inverse-square relationship between the electric field and the radius/distance...

Homework Statement Consider an infinitely long and thin line of charge, with density 8nC/m. Calculate the electric potential difference ((phi)1-2) between two points in air at radial disances 1mm and 3mm.Homework Equations I am assuming: Phi(r) = λ/2(pi)ε0 * ln(rR/r) where rR is a reference...

Homework Statement A point charge Q is located at point P(0,-4,0) while a 10nc charge is uniformly distributed along a semicircular ring as shown in the figure. find the value of Q such that E(0,0,0)=0 Homework Equations Q=ρLdl dl = ρd∅ (because ρ and z are constant)...

Homework Statement A point charge q is situated at the origin. A dipole p is placed at r. The angle θ is defined by \hat{p}\cdot\hat{r}=cos(\theta) Calculate the vector force Fp acting on the dipole by the nonuniform E field of the point charge. Homework Equations The Attempt...

Homework Statement A one point charge of -12µC is located at x=0m and a second point charge of -24µC is located at x=6m. Calculate the point where the electric field would be zero. I think that my physics professor worded this question wrong. Is there a point where the field would be zero if...

I'd like to know what the energy stored in the magnetic field created by a moving point charge is, as a function of speed. Hopefully, someone knows a relationship like this? or how to get this? I've got a straightforward approach below, but don't know how to integrate it. BfieldEnergy = f(|v|)...

Homework Statement There is a point charge Q = 4π nC inside a glass sphere which has the radius 1 m and the dielectric constant εr=10. This sphere is enclosed in a hollow metal sphere with an inner radius of 2 m and a thickness of 0.5 m. The task is to find the amount of the electric field...

Why should the force on a point charge always be toward a neutral conductor? I know this is a simple concept, but I'm having trouble grasping it. Any ideas? Thanks!

Homework Statement There is a charge located at the origin of magnitude 5nC. There exists a vertical line of charge, 2 meters in length, that runs from (2m,-1m) to (2m,1m). a) What uniform linear charge density must this line of charge have in order that the net force on a charge placed at...

At a certain distance from a point charge q there is small, dielectric ball. How would change the value of electrostatic force acting on the ball, if the value of a point charge would be doubled? According to F=k[(q1*q1)/r^2] there would be no force on the dielectric ball, because his resultant...

Problem: A +11 nC charge is located at the origin. Question: What is the strength of the electric field at the position x,y (-5cm, 5cm) ? I would think you would do this but when I try it I get the wrong answer for x-axis - E=k|q|/r2 For y-axis - E=k|q|/r2 Then \sqrt{}Ex^2 + Ey^2

A uniform electric field has a magnitude 2.40 kV/m and points in the +x direction. (a) What is the electric potential difference between x = 0.00 m plane and the x = 3.90 m plane? (b) A point particle that has a charge of +3.40 µC is released from rest at the origin. What is the change in the...