Point charges Definition and 359 Threads

Homework Statement What is a point charge? and what is the purpose of it when the definition of coulomb's law says,"force b/w TWO POINT CHARGES is directly proportional to their magnitude,and inverse to the square of their distance..."...I mean what is the use of it,why only point charges...

Homework Statement What would the electric field lines / equipotential lines look like between point charges that are set up with potentials of 20 volts and 30 volts versus point charges that are set up with potentials of 0 volts and 10 volts? The Attempt at a Solution At first I thought the...

Homework Statement Two point charges are located on the x-axis, q1 = -e at x = 0 and q2=+e at x=a.(a)Find the work that must be done by an external force to bring a third point charge q3 = +e from infinity to x = 2a. (b) Find the total potential energy of the system of three charges.The Attempt...

Homework Statement Find the magnetic forces acting on each electron in the attached image Homework Equations B = \frac{μ0}{4pi}*q*\frac{v x \hat{r}}{r^{2}} F_{m} = qv x B The Attempt at a Solution B_{1} = 10^{-7} * 1.6*10^{-19} *...

Homework Statement Two equal positive charges Q are fixed on the x-axis, one at +a and the other at -a. (a) The electric field E at the Origin O (b) The electric potential V at the origin O Homework Equations E=-dV/dr --> V=kQ/rThe Attempt at a Solution VNet = V0 + V1 I got V0 = -kQ/r...

Two point charges, one measuring +5μC and the other -6μC are placed .02m apart. What is the force between the two charges? Which point charge exerts the greater force on the other? Is it an attracting or repelling force? 1μC= 1x 10 to the negative sixthC

Homework Statement 2 questions regarding the answer I have been given for this problem. Attachments are the problem & relevant worked answer I disagree with. Problem Three charges are arranged in the xy-plane as shown in attachment. A charge Q is at the point A with (x, y) coordinates...

Homework Statement Two point charges Q1 = -58.6 mC and Q2 = +35.4 mC are located so that Q1 is directly above Q2. The coordinates of Q1 is (-12.0 cm, +15.6 cm). The two charges are 42.8 cm apart. Determine the coordinates of the location where the net electric field due to Q1 and Q2 is zero...

Can someone explain how you can have a zero electric potential between opposite charges? a charge would move there. I thought electric potential was the measure of energy per charge. wouldn't a 0 electric potential imply that a test charge cannot have any potential energy at this point? how is...

Homework Statement Three charges, each of magnitude 2 nC, are at separate corners of a square of edge length 1 cm. The two charges at opposite corners are positive, and the other charge is negative. Find the force exerted by these charges on a fourth charge q = +3 nC at the remaining (upper...

Homework Statement A positive point charge (q = +8.9 10-8 C) is surrounded by an equipotential surface A, which has a radius of rA = 1.3 m. A positive test charge (q0 = +2.7 10-11 C) moves from surface A to another equipotential surface B, which has a radius rB. The work done by the electric...

Homework Statement How to find the potential between two positive point charges? I don't know where I'm going wrong. ==I am adding V_1 and V_2. converted mC to C, cm to m, correct value of k. V1= kq1 / r1 v2= kq2/ r2. ==I am adding both of these, but I'm not getting...

Homework Statement How to find equilibrium points between four point charges? How do you determine whether these equilibrium points are stable, unstable, or neutral? I know the sum of the forces should equal zero, but that's it. How do you determine the stability of the equilibrium...

Greetings fellow physics adorers/ mathematicians, I was wondering if someone could help me with my posted problem. All the necessary details from the template are included in the screenshot on the right.

1. Homework Statement Three small identical metal spheres carry electric charges, +Q, +2Q, and +3Q. The centres of the spheres lie in a straight line at fixed positions R, S and T, such that the distance between the spheres at R and S is d1 and that between the spheres at S and T is d2. Assume...

I don't even know why I am having trouble with this problem. Homework Statement Two protons are initially an infinite distance apart. One of the protons is initially at rest, and the other is approaching the other at a certain speed. What kinetic energy must the other proton have so that their...

Homework Statement Point charges of -7 µC, 1.0 µC, and +7 µC are located along the x-axis at x = -1.0 cm, x = 0, and x = +1.0 cm, respectively. Locate a point on the positive x-axis where the magnitude of the electric field is zero. Homework Equations E=(kQ)/r^2 E(total)=E(1)+E(2)+E(3)...

Homework Statement Two fixed charges, +1.07 uC and -3.28 uC, are 61.8 cm apart. Where may a third charge be located so that no net force acts on it? Homework Equations Coulombs law The Attempt at a Solution q1 = 1.07 uC q2 = -3.28 uC q3 = q q1 ----- q2 ----- q q1 and q2...

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...

Homework Statement Two point charges with charges of +5μC and -100μC are separated by 15 cm. The magnitude of the force between these charges is: a) 1.99 N b) 4.02 N c) 20 N d) 199 N e) 400 N Homework Equations F = q1q2 * k / r^2 The Attempt at a Solution F =...

Homework Statement Two point charges (opposite signs, equal in magnitude) are a distance d apart. Point P is a distance z above both charges and horizontally equidistant. Find the electric potential at point P. Homework Equations Kq/r The Attempt at a Solution It's my...

Homework Statement "A point charge of 3*10^-6 C is at the origin and another point charge of -4*10^06 C is at point 0.1m away along the x axis. What is the magnitude and direction of the electric field at point 0.15m from the origin along the posting y-axis? Homework Equations E=...

Homework Statement A small metal sphere, carrying a net charge of q1 = -2.90 μC , is held in a stationary position by insulating supports. A second small metal sphere, with a net charge of q2 = -7.20 μC and mass 1.70g , is projected toward q1. When the two spheres are 0.800 m apart, q2 is...

Homework Statement A point charge q1 is held stationary at the origin. A second charge q2 is placed at point a, and the electric potential energy of the pair of charges is + 5.4 x10^-8 J. When the second charge is moved to point b, the electric force on the charge does - 1.9x10^-8 J of work...

Homework Statement Point charge 2.5 microC is located at x = 0, y = 0.30 m, point charge -2.5 microC is located at x = 0 y = -0.30 m. What are (a)the magnitude and (b)direction of the total electric force that these charges exert on a third point charge Q = 4.5 microC at x = 0.40 m, y = 0...

Homework Statement In the figure below, six charged particles surround particle 7 at radial distances of either d = 1.0 cm or 2d, as drawn. The charges are q1 = +8e, q2 = +8e, q3 = +e, q4 = +8e, q5 = +8e, q6 = +4e, q7 = +4e, with e = 1.60 10-19 C. What is the magnitude of the net electrostatic...

Homework Statement Determine the magnitude of the force between two point charges, Q1 = -2e located at (-3.60 cm, +4.10 cm) and Q2 = -8e located at (-0.60 cm, -8.60 cm). Give your answer in the form "a.bc x 10^(y) N". Homework Equations F = kq1q2/r2 The Attempt at a...

Homework Statement Two identical + 8.5mu C point charges are initially 2.5 cm from each other. If they are released at the same instant from rest, how fast will each be moving when they are very far away from each other? Assume they have identical masses of 2.0mg . Homework Equations...

Homework Statement Three point charges are arranged on a line. Charge q3 = +5.00nC and is at the origin. Charge q2 = -4.00nC and is at x = 4.50cm . Charge q1 is at x = 2.00cm. What is q1 (magnitude and sign) if the net force on q3 is zero? Homework Equations The Attempt at a...

Homework Statement See attachment Homework Equations The Attempt at a Solution I was successful with finding a solution. But, only because I tried the practice version of that (where you can see the answers) and noticed the equation I derived gave angles that, when summed with...

Homework Statement Four point charges, two of charge +q and two of charge -q, are placed in an arbitrary way. Each charge is located a distance r_i < R from the origin. Find the electric field at r >= R. Homework Equations According to Gauss's law, the field should be zero, right...

Let's suppose, we have two ideal point charges q_{1}, m_{1} and q_{2}, m_{2}. One of them comes from almost infinite distance with relative velocity v_{0}, w.r.t another charge. I'm curious how can we analyze this situation mathematically, i.e the equations of the motions of these particles...

Homework Statement These are really frustrating because they seem so simple, I work them all out without a hitch only to find that I'm wrong half the time and left wondering why. In fig 21-26a, particles 1 and 2 have charge 20 microcoulombs each and are held at separation distance d = 1.5...

I have a quick question about understanding the theory behind point charges and electrostatic potentials. I've not had any classes in electrodynamics, so I lack a comfortable foundation to help me think about these problems. I need to determine the electrostatic potential a certain distance...

Homework Statement I have a quick question about understanding the theory behind point charges and electrostatic potentials. I've not had any classes in electrodynamics, so I lack a comfortable foundation to help me think about these problems. I need to determine the electrostatic...

Homework Statement The energy stored by any pair of positive charges is inversely proportional to the distance between them, and directly proportional to their charges. Three identical point charges start at the vertices of an equilateral triangle, and this configuration stores 15 Joules of...

Homework Statement The 2.1mm diameter spheres in the figure are released from rest. What are their speeds vc and vd at the instant they collide? Spheres: C has 2nC of charge and a mass of 1g. D has -1nC of charge and a mass of 2g. The starting distance between the two spheres is 10mm...

Homework Statement A +15μC point charge Q1 is at a distance of 20mm from a +10μC charge Q2. Explain why there is a point along the line between the two charges at which the electric field strength is zero. After this, calculate the distance from this point to Q1 and Q2. The Attempt at a...

Imagine a cube with side lengths 'r', (like a dice) and we put point charges of charge Q at each corner of the cube. Issues with 2 subsections of this problem... First: What is the total electrostatic potential energy of the arrangement? Second: Add a charge -CQ to the center of the cube for...

Point charges q1 and q2 lie on the x-axis at points x = -a and x = +a, respectively. (a) How must q1 and q2 be related for the net electrostatic force on point charge +Q, placed at x = +a=2, to be zero? (b) Repeat (a) but with point charge +Q now placed at x = +3a=2. Can someone help me...

Homework Statement Two charges, one of charge +1.5 x 10^–2 C and the other of charge –2.7 x 10^5 C, are 20.0 cm apart. The positive charge is to the left of the negative charge. (a)Draw a diagram showing the point charges and label a point Y that is 5.0 cm away from the positive charge, on...

I'm having trouble trying to understand what a volt is, and I thought this question might be able to help me understand, so.. For example: If there are 10^6 electrons in one place, and 100 electrons in a different place, what will the potential difference between these two places be. Also...

Homework Statement Below is a graphic representation of the problem. With a point charge at the origin, calculate the difference in potential of point B relative to point A using the path integral. Homework Equations As I recalled, to find the electric potential difference, Vab = - ∫ E ° dl...

Homework Statement Hi! I have a question about calculating electric field made by finite point charges q_{1},q_{2},..., q_{n}. From the book "introduction to electrodynamics", you can see that the electric field E at a point P made by the finite point charges can be calculated by the below...

The above equation gives the EPE of two point charges separated by a distance r. Firstly, I do not understand how this formula gives the TOTAL EPE of the system. Secondly, let's say I have three deuterium nuclei moving towards one another with initial speed V. They all stop...

Homework Statement Two point charges are situated at A and B a distance of 35cm apart in a vacuum. The charge A is a positive charge of 16 μC and the field strength at X, a distance of 12 cm from A, is zero. Calculate: (i) The field strength at X due to the charge at A. (I found this to be...

A small charge of 4 x 10^-6 C is located at the point x=2 m, y=3 m in the xy-plane. A second small charge of -3 x 10^-6 C is at the point x=4 m, y=-2 m. A) Calculate the force that the first charge exerts on the second. Express your answer in both terms of magnitude and angle, and also in i ...

Electrostatics -- point charges and work Homework Statement A 3.0 μC point charge and a 9.0 μC point charge are initially infinitely far apart. How much work does it take to bring the 3.0 μC point charge to x = 3.0 mm, y = 0.0 mm and the 9.0 μC point charge to x = -3.0 mm, y = 0.0 mm? (The...

Homework Statement Two point charges are separated by a distance r. If the separation is reduced by a factor of 3/2, by what factor does the electric potential between them change? A. 3/2 B. 2/3 C. 9/4 D. 4/9 E. Sqrt(3/2) Homework Equations The Attempt at a Solution Honestly I...

Homework Statement The questions asks to consider the following comment about a situation where there are three point charges held fixed along a linear line. "There will be zero net electric force on the charge in the middle due to the other charges. Using Coulomb's law, the force due to...