Point charge Definition and 345 Threads

Homework Statement [/B] Figure 20-3, referred to below, is 0.800m wide and 0.400m tall with "A" in the top left corner, "+4 microC" charge in the top right corner, "+2 microC" charge in the bottom left corner, and "B" in the bottom right corner. Two point charges of magnitude +4.00 μC and...

This question seems to come up often, but I cannot find a satisfying explanation. There is a point charge +Q some distance above an infinite conducting plane. Supposedly, the electric field below the plane must be zero. I have trouble understanding why this is true. The total charge on the...

Homework Statement I need to create an equation that can tell me the electric flux through the surface of a sphere (centered at the origin) due to a point charge placed at various locations in/around the sphere. For example, find the electric flux through the sphere (of radius = 1) with a point...

If there was a spherical shell with negative charge density and a positive point charge inside the shell, the electric field lines from the point charge would just be radially outward towards the shell right? What about the case where there's a positive charge density and a positive point...

Homework Statement Non-uniform charge distribution over a randomly shaped object. This object will fit inside a sphere centered on the origin with radius r. What is the minimum distance from the origin that we can assume such that we can treat the electric field as if it were generated by a...

Hello, I have a conducting copper ring of inner radius a and outer radius b. point charges Q pass through the centre of this ring for time dt. so I guess I'm suppose to get a step function of induced current or something similar. 1)what is the equation relating the charge Q to the...

Does a point charge 'q' (say an electron) moving with constant angular speed ω in a circle of radius R constitute a current ? A rotating ring of uniform charge density is treated as a current flowing in the ring . On similar lines I think a point charge q is equivalent to current given by i =...

I'm having some trouble confirming Ampere's law for a moving point charge. Let's say we have a point charge q moving with velocity \mathbf{v}. The magnetic field it creates is given by \mathbf{B}=\frac{\mu_0 q}{4\pi r^3} \mathbf{v}\times \mathbf {r}. Now consider a circular loop centred...

Homework Statement (a)Consider a charged sphere of radius R centred at the origin with the spherically symmetric charge density ρ(r) = ρ0(r4/R4) where ρ0 is a constant and r is the radial coordinate. Find the charge dQ0 contained in a spherical shell of radius r0 < R and infinitesimal...

Hello again I seen in this forum about this problem but not in the special case when the point charge is at the center of the sphere how do I solve the series legendre polynomials?

Homework Statement A point charge q = -2.9 μC moves along the z-axis with a velocity v→ = (+7.3 x 105 m/s) k . At the moment it passes the origin, what are the strength and direction of the magnetic field at the following positions? Express each field vector in Cartesian form. (a) At...

I need to use coulombs law to describe the electric field due to a point charge in cylindrical co ordinates. I know the answer should have E = [ρ,0,z] with the azimuth as 0 but I can't show it using the standard electric field equations. please note I need to use E=q/4πε * r/|r|^3 I'm sorry I...

Homework Statement Q a) A charge is placed at a distance x from the center of a conducting sphere of radius R.Find the charge flown through the switch(from ground) when it is closed . b) In the above question replace the switch with an ammeter .What is the reading of ammeter if charge is...

Homework Statement Three charged particles are placed at the corners of an equilateral triangle of side 1.20 m. The charges are Q1 = 7.4μC , Q2 = -8.0μC , and Q3 = -5.7μC . Calculate the magnitude of the net force on each due to the other two. (The answer is prompted to be in Newtons)...

Homework Statement A point charge q is moved inside a hollow charged cylinder of radius R. The initial point A is a distance (3/4)R from the center and the final point B is at the center of the sphere. How much work is done by the electric force in this case? 2. The attempt at a solution I...

Homework Statement If the distance between a neutral atom and a point charge is doubled, by what factor does the force on the atom by the point charge change? (new force / old force) 2. The attempt at a solution Wouldn't the answer just be (new force / old force) = 0 since there is no...

In Griffiths Chapter 12, pg 527: Suppose a point charge is moving along x, we obtain the following E-fields: Questions 1. Is the vector R solely in the x-y plane? 2. What happened to the coordinate 'z' ? 3. Why are they only doing things in the 2-D plane? Can we use rotational...

Homework Statement Suppose a free electron in air is 1.1cm away from a point charge. What minimum charge must this point charge have to cause a breakdown of the air and create a spark? I already have the Electric field and force, which I solved to be E=7.2x10^6 N/C F=1.2x10^-12 N...

Homework Statement A point charge, Q, is "nailed down" on a table. Around it, at radius R, is a frictionless circular track on which a dipole \boldsymbol{p} rides, constrained to always point tangent to the circle. Show that the electric force on the dipole is (in the forward direction of the...

Hello , there are two questions I would like to ask from a educational paper i just read. For the first question please look the attached picture , it says that in the picture of the capacitor with the wire that has a gap in the middle and next to it when the gap is closed , it says that in...

A point charge Q is located on the axis of a disk of radius R at a distance b from the plane of the disk Show that if one fourth of the electric flux from the charge passes through the disk, then R= √3 b I have looked it through all angles possible for me but it seems to evade me. Got...

Homework Statement A point charge q is at the center of a spherical conducting shell of inner radius a and outer radius b. How much work would it take to remove the charge out to infinity? Homework Equations Potential, W = 1/2qV The Attempt at a Solution I am going at this in...

So here we are talking about solving this problem by method of images. The approach taken by most of electrodynamics textbooks is as follows: "If we wish to consider the problem of an insulated conducting sphere with total charge Q in the presence of a point charge q, we can build up the...

Homework Statement An infinite line charge of uniform linear charge density lambda = -3.1 mu or micro CC/m lies parallel to the y-axis at x = -1 m. A point charge of 0.7 mu or micro CC is located at x = 2.5 m, y = 3.5 m. Find the x- and y-components of the electric field at x = 3.5 m, y = 3.0...

Homework Statement The drawing shows a positive point charge +q1, a second point charge q2 that may be positive or negative, and a spot labeled P, all on the same straight line. The distance d between the two charges is the same as the distance between q1 and the spot P. With q2 present...

Homework Statement You charge a piece of aluminum foil (mass = 4.65 g) by touching it to a charged rod. The charged rod gives the aluminum foil a charge of 10 µC. Your professor brings a charged plate over and tells you to put the aluminum foil on top of the plate. To your surprise the...

Homework Statement Looking at the picture I have attached the problem is very straight forward. In the denominator of the equations I have posted the teacher uses 2\Pi but the book uses 4\Pi. Can someone please explain to me why is that. Homework Equations Book's equation: Teacher's...

Homework Statement A point charge q is moving relativistically with constant speed ##\beta## along the x-axis. At t = 0 a constant decelerating force F is applied in opposite direction of its velocity. If the charge stops after traveling a distance d, find the total radiated energy...

Say I have a stationary point charge with a matching charge moving past it at a velocity. What is the magnetic potential energy of the stationary point charge? The formula for magnetic potential energy involves pole strength so I am confused. I can calculate the B field the stationary particle...

A 10 nC point charge is at the center of a 2.0m x 2.0m x 2.0 m cube. What is the electric flux through the top surface of the cube? related equations: gauss's law -- Qin/e0 e0 = 8.85 x 10 ^-12 C^2/Nm^2 my attempt: 10 x 10^-9 C ________________________ = 1129.94 C/Nm^2 8.85 x 10...

Homework Statement See image Homework Equations KQ/r^2 The Attempt at a Solution I have seen several different ways of working this problem, but they have all failed on me. I tried this using the equation above from my book E = (8.99x10^9)(1036 C)/(4x10^-6m) E= 2.328x10^18 N/C I also...

Homework Statement Using the method of images, solve the following The Attempt at a Solution I have very little idea on how to solve this. I looked up various methods online and none seem to be what the lecturer has used. This is the solution he posted up, but as usual it is missing 300...

Homework Statement Consider a point charge q > 0 which is surrounded by a hollow metal sphere (uncharged) with inner radius R1 and outer radius R2. Use Gauss Law to determine the electric field E=E(r)er in the following regions: (i) 0 < r < R1 (ii) R1 < r < R2 (iii) r > R2 Homework...

Homework Statement 9uC charge at origin. How much energy does its electric field store outside a sphere centered about the origin with a radius of 5mm?Homework Equations C(sphere)=ab/(k(b-a)) V=kq/r U(cap)=(1/2)CV^2 E=kq/(r^2) a=inner radius b=outer radius The Attempt at a Solution...

Homework Statement A point charge q is at the center of an uncharged spherical conducting shell, of inner radius a and outer radius b. How much work would it take to move the charge out to innity? (find the minimum work needed. Assume charge can take out through a tiny hole drilled in...

Homework Statement In the figure the rod has a charge density of ßx, where x=0 is the left end of the rod, etc. Find the electric potential energy of the point charge q a distance a from the end of the rod and lying along the rod's axis...

Homework Statement How do the charges distribute when I have a spherical conductor centered cavity with a point charge not in center inside the cavity? See image: Homework Equations N/AThe Attempt at a Solution I would guess solution 1, but my tutor says it's 4, and I just can't believe him...

Homework Statement This is regarding setting up an integral to calculate the electric field on a point charge that is at a distance "a" from a uniformly charged rod of length "L". I have attached a picture of my work, which includes a diagram of the problem, and wanted to know if my thought...

Hi all, I was going through the derivation for the electromagnetic field of point charges by Griffith(Introduction to electrodynamics page 437). I'm missing minus sign somewhere: The book says that:\nabla(\vec{n}\cdot\vec{v})=\vec{a}(\vec{n}\cdot \nabla...

Homework Statement In the figure, what is the force on charge Q3? Q1 = 5×10-6C, Q2 = -3×10-6C, Q3 = 4×10-6C http://www.usi.edu/science/physics/pickett/206/4p2f1.jpg Homework Equations Coulomb's law The Attempt at a Solution I thought I could just find the charges on q1 and 3 and...

We know that the spacetime of General Relativity with a single electron in otherwise empty space is hardly curved, basically zero. In Kaluza–Klein theory with a single electron in otherwise empty space is there a type curvature due to the charge of a single electron? Is the amount of...

Homework Statement Three charges, q1, q2, and q3, are located at the corners of an equilateral triangle with side length of 1.49 m. Find the work done in each of the following cases: a) to bring the first particle, q1 = 1.33 pC, to P from infinity b) to bring the second particle, q2 = 2.99...

Gauss' Law has been fairly tough for me and I seem to be struggling to analyze situations properly and, specifically, decided on the net charge included in arbitrary symmetrical-shapes used for this law. Specifically, this one includes two spherical shells. Homework Statement A point charge q1...

Homework Statement Two +4 mC charges and two -4mC charges are arranged on a circle of diameter "d" as shown in the figure below. The magnitude and direction of the force on the +4mC charge at the top of the circle is: a) 6.39*10^6 N radially inward b) 1.2 * 10^7 N radially inward c) 2.4...

I've been thinking of 2 point charges separated by some distance in static equilibrium. When one charge is moved from rest, the EM field would change the way it looks at the location of the other point charge. This "changing in the looks" of the EM field as I understand propagates from the...

Homework Statement A point charge q is located at the center of a dielectric sphere of radius a. Find D, E, and P everywhere and plot your results. What is the total bound charge on the surface of the sphere? (I assume by "everywhere" my professor meant inside and outside the sphere.) (D is...

Homework Statement A point charge of -2 micro coulomb is located at the origin ,a second charge point of 6 micro coulomb is at x= 1m and y= 0.5 m Find the x and y coordinates of the position where the electric field is zero Homework Equations E=κq/ r^2 multiplied by unit vector...

Homework Statement A point dipole p is at the origin of coordinates, while a point charge q is at position r. Calculate the potential energy U of this system in two ways (a) by treating the dipole as a source and q as a test charge in the dipole field (b) by treating the dipole as a...

Hello friends, So I have a point charge with mass m and charge +e entering a uniform magnetic field B at velocity v from the "right". The field is perp to the velocity pointing "in", so I see that eventually this particle reaches a steady state of uniform circular motion (counter clockwise)...

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...