Point charge Definition and 363 Threads

After solving a homework problem, I realized I don't know what to do when there's a dipole and a point charge but the distance from the charges in the dipole is greater than the distance from the center of the dipole to the charge. As my homework problem stated, with a little context added...

Homework Statement Two positive charges q1 = q2 = 2.0 μC are located at x = 0, y = 0.30 m and x = 0, y = -0.30 m, respectively. Third point charge Q = 4.0 μC is located at x = 0.40 m, y = 0. What is the net force ((a)magnitude and (b)direction) on charge q1 exerted by the other two charges...

Homework Statement Homework EquationsThe Attempt at a Solution Let's consider the primitive model of atom i.e. the nucleus is surrounded by an electron cloud. Let's say that the nucleus has charge qa and it moves a distance d from the center in the equilibrium position. ## E = \frac {kq}...

Homework Statement Consider the arrangment of charges (fixed in place) shown in the figure. The square has side length d. (Figure 1) Now suppose the particle with charge q is released. It is "kicked" so that it's initial speed is v. After an unspecified trajectory, it is observed that the...

Some things I did not get are, 1): In the third para, it is said that potential approaches ##\infty## at ##Q##, why ? 2): In last para, The z component of field by ##Q## is said to be ##-Qh/(r^2 + h^2)^{3/2}##, Why ? should not it be ##+Q## not ##-Q## has the charge itself is positive. 3): I...

Homework Statement I am trying to derive an expression for the potential of a positive point charge by bringing in another positive test charge in from infinity to a point at a distance R from the point charge. Homework Equations $$V_f - V_i = - \int \vec E \cdot d \vec r \, dr$$ The Attempt...

Homework Statement : STATEMENT:[/B]A point charge at rest is released in an electric field. It will move along the electric field line...(1) REASON: The force on a point charge is along the field line...(2) State whether: A) 2 is the correct reason for(1) B) Both (1) and (2) are correct but 2 is...

I need help trying to set up this problem. I want to find the capacitance between a point charge and a finite plate (or disk) as the point moves from above the center of the plate to some distance off the plate. I have been able to simulate this problem using FEM, however, there should be a...

Homework Statement We have an electric dipole with moment P=2*[10][/-5] pointing in x direction. What is the force experieced by dipole at origin when a point charge Q=3*[10][/-4] is located at (0.014 m ,0,0) Homework Equations 1. [E][/dipole]=(1/4π[ε][/0])(2p/r3) 2. p=qs 3. F=qE 4. τ=pEsinϑ...

When we say a fundamental particle is 0 dimensional, is that literal or figurative? Is it physically possible that a particle has it's properties (like charge, mass) spread out in a finite volume, but can be "shrunk" to increasingly small volumes when we measure it?

Firstly I appologize, that I am not native english speaker and I don't study physics(but cybernetics we are getting just some general knowledge about physics), but hopeffuly I will write this right. Homework Statement We know that inside of a conductive object is protected from influence of...

Homework Statement Around a point charge there are three points: A, B and C. Determine the electric field vector for those points. Also, determine the force vector for q0 if it was in point B. Q = 10 µC, a = 1 m, b = sqrt(3) m, q0 = 10 pC 2. The attempt at a solution Here is the attempt at a...

1. Homework Statement A fixed parallel plate capacitor is charged. A point charge is starting to move with an initial speed 1.0 m/s at shown initial position. The capacitance is 5.0 F. The mass of the point charge is 0.80 kg. Assume that the plate length is infinite. No gravity. The initial...

Homework Statement I have two related questions here. 1. A positive point charge is moving directly toward P. The magnetic field that the point charge produces at P is? 2. Two positive point charges move side by side in the same direction with the same velocity. What is the direction of the...

Homework Statement Homework Equations Work = - (integral of) (E dot dl) The Attempt at a Solution Hi, I know that the right answer is D zero, but I fail to understand why. I said that the answer was A as I have different charges, and I thought that depending on how I approach each...

Homework Statement The geometrical positions of point-like charges and point A situated in the xy-plane in terms of the length parameter a. The vector of electric field E at point A is shown schematically and measured as E = Exi + Eyj (that is, both Ex and Ey are given). If possible, find the...

An accelerated charge emits radiation and so must lose energy. This implies that it feels a "reaction force" in the direction opposite the motion. Since EM interactions conserve energy/momentum, it must be possible to describe the reaction force in terms of EM fields acting on the charge. These...

Homework Statement ≈ What is a 3D representation of voltage using Kq/r assuming a positive point charge and what is the equation in cartesian and cylindrical form2. Relavent equations Kq/r 3. Attempt at solution[/B] I was trying to get a better understanding of Voltage, to really FEEL...

Homework Statement A particle of mass 52[kg] is at 5.0[m]ˆi a particle of mass 13[kg] is at 12[m]j, and a particle of mass 13[kg] is at −12[m]jˆ. What is the gravitational force on the 52[kg] mass due to the mass at 12[m]jˆ? answer: −1.0 × 10−10[N]ˆı + 2.5 × 10−10[N]jˆHomework Equations...

This is a really abstract question, and I'm absolutely clueless on how to approach it. I know W= F*d, where F=force and d=distance, as well as W= PEa-PEb. The question reads: The diagram shows an isolated point charge. Marked are four paths (A, B, C, and D) from a point (P1) to point (P2). The...

Homework Statement Take the expression 21.11 (pictured below, specifically the bottom one) for the electric field above the center of a uniformly charged disk with radius R and surface charge density σ, and show that when one is very far from the disk, the field decreases with the same square...

Hi. I'm currently learning about magnetism, however the course I'm in doesn't combine special relativity with E&M so I just wanted to do some personal exploring. The magnetic field for a point charge is proportional to V1 x R of the charge. Then, the magnetic force is proportional to V2 x B...

Homework Statement If a charge of +2 µC and mass 2 g is taken to (0,0,4) in the presence of an electric field due to a ring {R : x2 + y2 = 25,z = 0} of uniform charge density ρL = +3µ C/m, and then released, find the maximum velocity it gains. Given in the problem: You solve the equation 1/2...

Homework Statement [/B] Three point charges each of 4 µC are situated at the three corners of an equilateral triangle of side 4 m. Find the work done in moving one of them to a point mid-way between the other two. Solution: The Potential difference VAB between two points A and B is the work...

Homework Statement A point charge q1 = 4.40 μC is at the origin and a point charge q2 = 6.00 μC is on the x axis at x = 2.49 m. i) Find the electric force on charge q2 ii) Find the electric force on charge q1 Homework Equations Coulomb's law F = k (q1q2)/d^2 The Attempt at a Solution Part...

Homework Statement Consider two equal point charges q, separated by a distance 2a. Construct the plane equidistant from the two charges. By integrating Maxwell’s stress tensor over this plane, determine the force of one charge on the other. I have the full solution, but I'm confused on one...

bear with me, i know that this question has been asked many time , but i would like a definite answer, now, starting off the external charge density on the outer surface of sphere WILL be uniform by unique solution of Laplace equation and letting the sphere be huge, so, electric field due to...

If there is a small object with positive charge placed above a metal plate, the object induces a negative charge on the surface of the plate facing the object. Let's call this surface as S1. (The metal plate is initially uncharged). But from conservation of charge, the net charge in a metal...

For instance, at a point 1 meter from a 1 nC charge the voltage (potential difference) from the formula V = Kq/r, is given as 9 volts, 9 J/C. So what does it then mean to call a battery 9V, 9 J/C? Is this a battery capable of taking a 1 C charge from infinity and pushing to within 1m of a 1 nC...

Homework Statement A ring of radius R lies in the x-y plane with the center at the coordinate origin. The ring is uniformly charged with with a uniform charge density +λ. a) Charge +q is brought along the z-axis from -∞ to the center of the ring. What is the increase in total potential energy...

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 point charge out to infinity (through a tiny hole drilled in the shell)? [answer: q2/8πε0)(1/a - 1/b) Homework...

Homework Statement Find the electric field (both magnitude and direction) at point P located between the charges q1 = -3C and q2 = +4C. Point P is 1/3 of the charges' separation distance from q1 and 2/3 of the charges' separation distance from q2. Homework Equations E = kq/d^2 Etotal = E1 + E2...

Homework Statement Two points charges. q1=2.4e-6 C is located at (0,0) q2=-5.7e-6 C is located at (3,0) I must calculate the magnitude of the Electric field at (0,0) Homework Equations E=kq/r^2 ; k=9e9 The Attempt at a Solution The electric field at (0,0) due to q2=9e9x(-5.7e-6)/3^2 =...

Hello! I'm having a problem with the Green's function solution of the simplest case of Poisson's equation, namely a single test charge ##q## located at ##\boldsymbol r = \boldsymbol r'##. I've read the related posts on Poisson's equation via Green's function formalism, but they do not answer my...

Homework Statement If a point charge is inside a Gaussian sphere but is off center, why is its electric field still Qenc/(e0*4*pi*r^2)?Homework Equations surface integral of E*da=Qenc/e0The Attempt at a Solution If we draw cones out from the charge. the 2 surfaces from the cones' intersection...

Homework Statement Reading a journal from that crazy old retired physics professor on the hill, you stumble upon a scheme to generate high frequency (HF) radio waves (λ = 10 m). It requires generating an electric field that diverges from a point and increases in strength linearly with respect...

Homework Statement [/B] 14. Two positive point charges of magnitude Q and 9Q are a distance d apart, as shown in Figure 2.22 (image attached). a) Calculate the electric field strength at point P, a distance d/4 from Q. A third positive point charge is placed at P and is then displaced a bit to...

Homework Statement Here is the problem I am stuck on. I have checked my process multiple times, but have come up with the same wrong result. I would like to find out where by error of thinking lies. "An infinitely long line charge of uniform linear charge density λ = -1.30 µC/m lies parallel...

Hi there. I'm reading Jackson's Classical Electrodynamics. 1. Homework Statement In chapter 6, the equation for the electric field of a moving point charge is derived. I could follow the mathematics to get the electric field for the moving charge, which is given in equation 6.57 in Jackson...

Homework Statement My book demonstrates how a uniform electric field through a box generates a net flux of zero. I was wondering if the same would happen from a point charge outside of the cylinder on one end instead of a uniform electric field. Homework Equations Flux = E⋅A The Attempt at a...

Homework Statement An insulated conducting sphere of radius ##R##, carrying a total charge of ##Q##, is in the field of a point charge ##q## of the same sign. Assume ##q\ll Q##. Calculate and plot the force exerted by the sphere on ##q## as a function of distance from the center. In particular...

Homework Statement [/B] 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...

In this problem, we have a positive point charge in a conducting thin shell. The shell is overall neutral. The complication is that the charge is not at the center of the sphere but maybe half radius away. How do we find the electric field and potential inside the sphere? Why the distribution...

Homework Statement Three charges are placed as shown in the figure below. The magnitude of q1 is 2.00 µC, but its sign is not known. The charge and sign of q2 is not known. We do know that q3 is +4.00 µC and the net force on q3 is entirely in the negative x-direction. a.) Deduce the signs of...

Homework Statement The electric field map is shown below. (Take it to be a self-consistent scale drawing at a particular moment in time.) where \mathrm{q}_4 = +10 C, \mathrm{q}_6 = +10 C What is the charge of \mathrm{q}_5 ? Homework EquationsThe Attempt at a Solution I've tried the...

Homework Statement A point charge q =+6.4 \mu \mathrm{C} is placed at each corner of an equilateral triangle with sides 0.29 \mathrm{m} in length. What is the magnitude of the electric field at the midpoint of any of the three sides of the triangle? Hint: if you are careful to examine the...

Homework Statement A point charge q1 = -6.1 μC is located at the center of a thick conducting shell of inner radius a = 2.8 cm and outer radius b = 4.8 cm, The conducting shell has a net charge of q2 = 2.6 μC. Homework Equations E = (kQ)/r2 F = (kq1q2)/r2 The Attempt at a Solution I honestly...

Homework Statement Find the Electrostatic potential energy of a cubical configuration of point charges. (One charge on each corner of a cube). Each of the charges is 3.00e and the edge of the cube is 3 cm. Homework Equations U = kqQ/r The Attempt at a Solution I'm pretty sure I understand...

Do charges exist as a point or a distribution? Or does it depend on the situation? Or does the concept of image mean that it's very difficult to tell, and if so why is the point charge model being pushed so hard, what phenomena does it explain that distributions cant?

Homework Statement What is the magnitude of the electric field at the two points on the x-axis where the electric potential is zero? Homework Equations E= kQ/r^2 The Attempt at a Solution I tried setting three cases, between the charges, to the right of the positive charge, and to the left of...