Charges Definition and 1000 Threads

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 =...

Earnshaw's theorem http://en.wikipedia.org/wiki/Earnshaw's_theorem gives a straightforward reason why we can't have a static equilibrium for a system of point charges. For some time I've been trying to find out if anyone's worked out a similar proof for the impossibility of a dynamic...

Thank you all for helping. Today I have another question: If individual charges move at around (10^ -4) m/s, then how come signals are being able to travel at great speeds- like approaching speed of light? Isn't it too fast?

Homework Statement Two circular lines of charge are centred at the origin and lie on the xy plane. The inner loop has a radius of a and a total positive charge q. The outer loop has a radius of b and total negative charge -q. (a) Use Coulomb's Law to calculate the electric field on the z-axis...

what are the generalised and more quicker ways of finding Force that multiple charges (4 charges along the y-axis and x-axis at most) exert on the origin charge Q. i have used a cartesian plane to try solve for the vectors but seem to not get to the right answer.

Hello, so this was a past assignment question that I attempted. I got the right answer but in an incorrect way (I guess my thinking was not based on the concept?) 1. Homework Statement Three point charges of charge Q = 10...

Hello. I was trying to understand the mathematics underlying Faraday cages. After hours of research on the web, It turns out that there are very few mathematical analysis related to Faraday cages, even in the electrostatic case, and those that I read do not satisfy me. So, I tried to solve the...

Homework Statement [/B] Two point-like charges are placed as shown in the figure, r1 = 28.0 cm and r2 = 56.0 cm. Find the magnitude of the electric field at point (p) shown in the figure. Let q1 = −13.0 µC, q2 = +30.0 µC. Homework Equations [/B] E1 = k*q1 / r^2 3. The Attempt at a...

1. How far apart must two point charges of 75.0 nC be to have a force of 1.00 N between them?Homework Equations F = k Q1Q2/r2[/B]3. 1N = 9e10 * 75e-10 squared/r squared r2= 9e10 * 75e-10 squared/1N r2= 9*75*75e-10 r2= 5.0625e-7 r= square root of 5.0625 * square...

I'm studying for the physics GRE and am fairly poor with EM. 1. Homework Statement What is the work needed to assemble four point charges q into a regular tetrahedron of side length a? Homework Equations W = 1/2ΣqiV(ri) The Attempt at a Solution Assume that the origin is at one of the...

Let's say I keep on dropping electrons on one spot of a Rindler horizon. Does the charge of the spot increase without a limit? When the charge of the spot is very large, does the spot exert a Coulomb force on the electron I'm about to drop, causing the electron to start moving away from the...

Homework Statement Four charges equal in magnitude of 20.0 microC are placed on the four corners of a square with side length 0.180m. Determine the electric field at the centre of the square. (-q) ---------- (+q) l l l l l...

four charges each equal -Q placed at the four edges of a square and a charge q is placed at the centre. if system is in equilibrium the value of q is, the answer is q = Q/4 * ( 1 + 2(√2) can anyone please solve this, would be great

A thin metallic spherical shell contains a charge Q over it. point charge +q is placed in side the shell at point T separated from the centre by a distance a. Another point charge q1 is placed outside the shell at a distance b from the centre find the electric field at the centre due to the...

What I studied was that the force on one charge due to another equal charge in the system of two charges was, (say) F; whereas the force on the other charge due to the first charge was found out to be -F. Hence they add up to be zero. So can I say that the two equal charges are in electrostatic...

Having a question regarding Faraday's cage,Applying a magnetic field over the cage, will cause the charges in the conducting cage to rearrange, thus causing another field which opposes the first field. This will give a net field inside the cage of zero (this is why we are safe in a car during a...

I have often wondered why, when you consider the equivalence principle, accelerated charges radiate. Its not something the EM books I have read seem to actually address. Anyone know the answer or is it tied up with weird stuff like runaway solutions to the Lorentz-Dirac equation that really...

I'm having an issue with the equation that Griffith uses to derive the field of a polarized object. In Chapter 4, Section 2.1, he starts off with equation 4.8 with the 'script r' to denote the distance between a point outside the distribution P (and the origin) and the dipole (and the origin)...

Homework Statement The first one has charge Q is at "-a" from origin the second is at "+3a" which is an unknown charge.What are the values for unknown charge if at the origin the net electric field they produce with magnitude 2Ke(Q/a2) Homework Equations Ke (Q/a2)i - Ke(q/9a2)=2Ke(Q/a2)i if...

Simply, is there a difference between a positive charge repelling a positive charge and a negative charge repelling a negative charge. More of what I am asking, is there any special properties that one has over the other, and vice versa.

The sistem above is the one I'm interested in. There is two equally charged spheres spinning on a plane. The line has L=\sqrt{2} m and the spheres weight 0.6Kg. The angular speed is \omega = 2rad/s. The radius for the circular trajectory is R=1m and so the centripetal force is...

Hey guys, new to this forum. Currently studying a mechanical engineering degree (first year), but I'm having real problems with some of the electrical side of it, mainly electric fields. Any tips or help on how to answer these two questions: 1. Two point charges of +3.1 muC are separated by a...

Homework Statement Find the vector potential from two oscillating point charges on the z axis. Homework Equations z_+ = -z_0cos(\omega t) q1_+ = q2_+ = q The Attempt at a Solution I know how to solve this problem when the two charges are equal and opposite, but now the two oscillating...

Homework Statement Two charges are placed on the x axis. One charge (q1= +8.5 micro coulombs) is at x1 = +3.0cm and the other (q2 = -21 micro coulombs) is at x1 = +9.0cm. Find the net electric field (magnitude and direction) at (a) x = 0cm and (b) x = +6.0cm Homework Equations E = kq1/r^2 The...

Homework Statement It is the last part, part (c) that I'm having trouble with, but I'll post the entire question for clarity. Three charges (q) form the vertices of an equilateral triangle. A fourth charge Q ( Q = -q ) is placed at the center of the triangle. (a) will the charges at the...

I'm a little confused by the formula used to find the charge between 2 charges. The formula is fe = kq1q2/r^2. How does this work for two objects such as a neutral object and a charged object? They are attracted to each other due to distribution of the charges, but the formula doesn't show that...

In the superposition of charges, both directions is said to occur at the same time.. question: is this simultaneous occurrences observable (viewable) at the same time? I presume the left an right direction are eigenstates, but it is commonly said you can only observe one eigenstates at a time...

Can experiments differentiate like vs. opposite charges? Two electrons repel, whereas an electron and positron attract. But for macroscopic observers, in the absence of annihilation, could anyone tell whether paths deflected due to attractions or repulsion? Or, is there always annihilation...

Homework Statement Three positive particles of charges 11 μC are located at the corners of an equilateral triangle of side 15.0 cm. Calculate the magnitude and direction of the net force on each particle. Homework Equations Coulomb's Law The Attempt at a Solution I think, that this is easy...

Homework Statement Three point charges q,q and -q lie at three corners of an equilateral triangle of side length d with -q at the apex. If an electron is released from rest midway at the base (point P) what is its KE when its reasonably far away? Homework Equations V = kq/r, U = qV The...

Homework Statement a.) [/B]A proton and an "positron" (identical to an electron, except positively charged) are brought ##5µm## apart and released from rest. What is the initial potential energy stored by this system? b.) In all of the previous problems on this homework, the system's...

Hi everybody, The situation is the classic one: a point charge q+ in a distance d above a conductor plane grounded: The conductor is grounded so V = 0, for z = 0. Also, far away from the system (x2 + y2 + z2 >> d) V --> 0 The argument to replace it for a q- charge seems perfect to me. What I...

Hey, Just wanted to thank everyone for their time to help solve people problems, I can generally find all my answers here but I made an account now because i can't seem to find a related problem to this. In general the textbook for these types of problems make the plane z=something. In this...

Homework Statement The distance between two small balls of the same radius and charge is r. If we release the balls they approach, touch and then repulse each other. When their distance is 4r the repulsive force is 1/20th of the initial force. What is the charge of the first ball if the...

Homework Statement I was looking for some practice problems in my textbook and found this problem that I was just a little stuck on. I drew the diagram from my textbook with the givens of the problem. Homework Equations ∲E*dA = Q (inside) / ɛ0 The Attempt at a Solution For r less...

Suppose there are N charges fixed at arbitrary locations , how do I calculate the total electrostatic energy ? I can think of two ways. one being the straightforward coulomb's law : k=1/(4*pi*ε) Q=k/2 * ΣiΣj qiqj / |ri-rj| ; i≠j the other method is to integrate energy density with respect...

How do you determine the force between two objects based on their net charge. For example, if you have a charged balloon and you know the value of that charge and the distance it is away from a neutrally charged wall, how can the attractive force between the wall and balloon be determined?

An accelerating charge radiates light. But in its own frame of reference it is stationary. So it does not emit light. How is this explained? Extreme Example: A charge inside an elevator is falling in a gravitational field. The elevator is lined with a light sensitive sensor that triggers a...

Homework Statement Two point charges q1 and q2 are held in place 4.50 cm apart. Another point charge -2.00μC of mass 6.00g is initially located 3.00 cm from each of these charges and released from rest. You observe that the initial acceleration of -2.00μC is 354m/s^2 upward, parallel to the...

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...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Three point charges are located at the corners of an equilateral triangle as Q1 in the top, charge Q2 in the left corner and charge Q3 in teh right corner. Each leg of the triangle has a length...

1. two point charges q1 and q2 with a combined charge of 20 micro coulombs are placed 3m apart. If one repels the other with a force of 0.075N calculate; the value of q1 and q22. k=8.987x10^9 F=kxq1xq2/r^2 E=kQ/r^2 E=f/q3. I've tried to work out the charge by working out the...

In Gaus's law when the integral is set up, we don't account for the charge outside the closed area. Why is this? How does this law work when the charges outside are not accounted for and only the charges enclosed is in the equation? I need an explanation why Gaus's law still works for...

Homework Statement I am trying to graph the flux density field between two infinite line charges located at y = 1 and y = -1 Homework Equations I am trying to do it using the equation for a line charge that I got from lecture notes. The above equation is derived from this: Here is the...

Homework Statement 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 neutral...

This is a concept that has long since plagued me. I will quote an article off of Google about the concept I am confused about: "Consider a collection of static point charges located at position vectors (where runs from 1 to ). What is the electrostatic energy stored in such a collection...

Homework Statement What is the potential energy of the system composed of the three charges q1, q3, and q4, when q1 is at point R? Define the potential energy to be zero at infinity. Charges are arranged in a triangle, with q3 and q4 located up and down 2.2 cm from the origin, and q1 on 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 If Q1 in the above figure is twice Q2 and both are positive, where can a point of zero potential be found?Homework Equations V = kq/r The Attempt at a Solution I know that eventually I'll have to set it up so that kq/r = kq/r, but my problem is, how do you know where this...

Homework Statement Three fixed point charges of +2 nC, −3 nC and +4 nC are located inside a thin uncharged metal spherical shell of radius R = 2 cm, as shown in the picture attached. Calculate the strength and direction of the electric field at position P, being 10 cm from the centre of the...