Charge Definition and 1000 Threads

Is the potential energy of a symmetric planar (x,y) charge distribution lower than any non symmetric distribution ? from the discussion on Gauss's law and symmetric charge distributions I would think so because the electric field could only be normal to the (x,y) plane in the symmetry case but...

Homework Statement Positive charge Q is distributed uniformly along the x-axis from x = 0 to x = a. Determine a. The electric field produced by the charge distribution Q at points on the positive x-axis where x > a. b. A point charge q is then placed at x = a + r. Determine force on q due to Q...

Why are these batteries stated as 12V batteries if often they have a reading of greater than 12V e.g 13 or 14 and when you rev the engine hard while in neutral and do a voltage test on some components in the car circuit you get a reading of much much greater like 40V! How is this working? Could...

Homework Statement Consider a ring of radius R placed on the xy-plane with its center at the origin. A total charge of Q is uniformly distributed on the ring. a) Express the volume charge density of this configuration ρ(s,Φ,z) in cylindrical coordinates. b) Express the volume charge density of...

Homework Statement A point charge ##q = −5.0\times 10^{−12} C## is placed at the center of a spherical conducting shell of inner radius 3.5 cm and outer radius 4.0 cm. The electric field just above the surface of the conductor is directed radially outward and has magnitude 8.0 N/C. (a) What is...

Homework Statement I just have a general question about Guass's Law and the cylinders above. I don't really understand what the difference is between the 2 cylinders? They are both charged, but one of them does not have an electric field inside the cylinder because it a conducting...

Hi For a 1200 watt tool, there are 20, 40 and 60 volt batteries, and in the case of a 2 amp hour (7200 Coulomb) battery, using energy = charge x voltage gives different values of stored energy for each of the three batteries, which are 144000, 288000 and 432000 Joules. Is this correct? Thanks

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 identical thin rods of length L carry the same uniform line charge distribution (charge per unit length) of . If the two rods are collinear (aligned along the same line), with a distance of d between their nearest ends, calculate the Coulomb force (magnitude and...

Homework Statement An infinitely long line of charge has linear charge density ##λ=4.00_{10^{−12}} \frac{C}{m}##. A proton (mass ##m_p=1.67_{10^{-27}}kg##, charge ##e=1.602_{10^{-19}}C##) is ##r_a=0.18m## from the line and moving directly toward the line at ##v=1000\frac{m}{s}##. Homework...

Hey there I'm trying to reconstruct the entire table of all Dirac bilinears under C, P, T and CPT transformations of page 71 and hit a wall on charge conjugation. It's a computational problem, really. Here's a specific problem: Equation 3.145 we have $$-i\gamma ^2 \left( \psi ^{\dagger...

Homework Statement A proton is at the origin and an ion is at x1 = 6 nm If the electric field is zero at x2 = -3 nm , what is the charge on the ion? Homework Equations for ion The Attempt at a Solution https://imgur.com/ryyuQBq I just have used all my attempts besides one. So I...

Homework Statement Point charges ##q_1=50 \mu C## and ##q_1=-25 \mu C## are placed 1.0 m apart. Where must a third charge ##q_3=20 \mu C## be placed so that the net force on it is zero? Homework Equations $$\vec F=\frac{1}{4\pi {\varepsilon}_0}\frac{|q_1q_2|}{r^2}\hat r$$ The Attempt at a...

Consider an electric charge Q with rest frame R and a closed conductive loop L with rest frame R'. Q is moving relative to L, and vice versa. In R, the loop is moving and receives no magnetic flux from Q thus no voltage according the integral form of Faraday's law. In R', the loop receives...

Two identical front surface mirrors are hung in a vacuum chamber with a high vacuum with a bit of bias of their mass wanting to lean into each other so they don't separate on their own. The metal surface is connected to a variable high voltage source. Both mirrors are connected to the same...

Homework Statement A charge Q=5.14 nC is located at the center is located at the center of a Gaussian sphere of radius R=10.0 cm . The sphere lies within a uniform upward electric field E=2100 NC The net outward electric flux through the sphere is What? Second problem (bonus round!) A...

Homework Statement A beam of electrons passes undeflected through two mutually perpendicular electric and magnetic fields. If the electric field is cut off and the same magnetic field maintained, the electrons move in the magnetic field in a circular path of radius 1.14 cm. Determine the ratio...

This is a question born out of a homework thread that lead to a discussion between @haruspex, @rude man, and myself. Link here https://www.physicsforums.com/threads/what-is-the-charge-of-each-conductor-afterwards.923909/ . I feel this question deserves its own thread and hopefully we can get...

Greetings! I'm new here and I think about this place as soon as I see what the statement asks. Homework Statement Considering the volumetric density ρv=(e-2r/r2), figure the total charge (ℚ) of the universe. Homework Equations [/B] ρv=ΔQ/ΔV -> (ΔQ ∝ ΔV) ℚ=∫v ρv dxdydz The Attempt at a...

Homework Statement Two identical conductors are brought into contact. Initially one conductor has a charge of +30 x10^(-6) C, what is the charge of each conductor afterward? Does it matter how the contact is made? Homework EquationsThe Attempt at a Solution Well since they are conductors...

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 "A straight, nonconducting plastic wire ##x=9.50_{10^{-2}}m## long carries a charge density of ##λ=1.3_{10^{-7}} C/m## distributed uniformly along its length. It is lying on a horizontal tabletop. If the wire is now bent into a circle lying flat on the table, find the...

Homework Statement "Let there be two point charges ##q_1=3.5μC## and ##q_2=-3.5μC## located at ##(0,0.3 m)## and ##(0,-0.3 m)## respectively. What force do these two charges exert on a test charge ##Q=4.5μC## at ##(0.4 m,0)##?" *title should read "due to two point charges"* <Moderator's note...

Hi, initially I would like to share this link related to derivation of maxwell equation : http://www.physicspages.com/tag/amperes-law/ My question is : in this link, it states interesting situation in electrodynamics is one where the current density is constant in time, but the charge density...

Homework Statement You charge a parallel-plate capacitor, remove it from the battery, and prevent the wires connected to the plates from touching each other. When you pull the plates apart to a larger separation, do the following quantities increase, decrease, or stay the same? (a) C (b) Q...

Dear all, I know the sources of magnetic field are moving charges or varying electric field. I also know that subatomic particles(even neutron) have their own magnetic moment due to its quark and spin and their magnetic moment is explained by invoking quantum mechanics(though I don't know how...

Hello, I was looking over my notes and I was trying to figure out when we integrate Q enclosed when Q = ρ*d(volume). If there's one thing I've learned from physics II you only integrate when a field is non-uniform. I'm just wondering how we know when it's uniform (usually the problem will tell...

No one could ever explain to me the mechanism how attraction of positive and negative charge works. Can you? (Exchange of (virtual) photons only explains repulsion.) An electrical field is playing hide and seek.

Charge moving in constant linear velocity does not produce magnetic field... If not, please provide an explanation...

<Moderator's note: Moved from a technical forum and therefore no template.> Hi, I've been doing this excersice but I'm not quite sure about my answer It says: A positive charge Q is located at the origin of a three-dimensional coordinate system. Consider and imaginary square surface of side...

Homework Statement A capacitor of capacitance C is charged to a potential difference v from the cell and then disconnected from it. A charge Q is now given to its positive plate. The potential difference across the capacitor is now? Homework EquationsThe Attempt at a Solution V is the...

Does a current (or a mobile charge) exert any force on the stationary charge (charge with no motion)? We know that the current produces a magnetic field around which exert a magnetic force on mobile charge and now I like to know whether the current exert force on a stationary charge.

Homework Statement "*Question 44: Uniform Circular Motion Inside Sphere of Charge The tau particle is a negatively charged particle similar to the electron, but of much larger mass - its mass is 3.18 x 10-27 kg, about 3480 times the mass of the electron and about twice the mass of a proton or...

This is 'optional homework' that the teachers don't see and we write down just to practice. So I want someone to review it and tell me if I truly understand these concepts :) thanks in advance 1.What is the smallest charge (quantum of charge) that any paricle an exert? A: An electron/proton of...

Homework Statement Find the electric field of an infinitely long straight wire of charge ## \lambda## C/m at a point ##r= ix+jy## Homework Equations ##\int E.da = \frac {Q}{\epsilon_0}## ##E= \frac{\int dq}{4\pi\epsilon_0 r^2} ##r The Attempt at a Solution Drawing a cylindrical gaussian...

I have solar panels fitted, with a capacity of 2.4 -2.5 kW. I am considering buying lithium battery storage for evening use. What would be the largest battery system I could charge from this setup?

Homework Statement What is the force F on the 1.0 nC charge at the bottom in the figure? Give your answer in component form. In the figure, the +!.0 nC charge is adjacent to a +2.0 nC charge to the left at a 45° angle, a -6.0 nC charge directly above, and a -2.0 nC charge to the right at a 45°...

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 Homework EquationsThe Attempt at a Solution ##\rho = b r \\E =\frac { k r^2} {4ε_0} \\ p ∝ E^a \\E \left ( r=d \right ) = \frac { k d^2} {4ε_0} \\ p = q d \\ d ∝ d^{2a} \\a = ½ \\p ∝ √E ## PART B ##\rho ∝ r^n \\E ∝r^{n+1} \\ p ∝ E^a \\d ∝d ^{{n+1}a} \\## For eq. 4.1 to...

Homework Statement I uploaded the Ex. 3.2. Homework EquationsThe Attempt at a Solution On the spherical surface, the potential due to q'' at center is going to be constant. q''= V0 R\kLet's say that the potential of the neutral conducting sphere is V0. Now, to calculate the force of...

Currently, I am reading this article which introduces electromagnetism. It gives a function for the charge density as: $$\rho = q\delta(x-r(t))$$ The paper states that "the delta-function ensures that all the charge sits at a point," but how does it do that? Also, if ##r(t)## is the trajectory...

Homework Statement Homework EquationsThe Attempt at a Solution I understand I, but struggle to figure out whether rod S is an insulator or conductor. Does this have anything to do with charged object attract uncharged uncharged object? Please help~[/B]

I'm trying to understand the concept of Butler-Volmer equation and its kinetic derivation. What I don't know and didn't find it anywhere is related to the charge transfer coefficient. Let's have a reaction coordinate during electrode reaction with a transfer of electrons: Can anybody explain...

Homework Statement There are three identical conducting spheres, A, B and C. They are initially charged as q_A = 0, q_B = 0, q_C = +Q. Initially, A and B are connected by a wire. Then the spheres are connected (by a wire) as follows: 1) A to C (while A is still connected to B) 2) Connection...

Homework Statement Homework EquationsThe Attempt at a Solution I chose B because I thought the positive charges in the insulator would attract the negative charges in the conductor to one side. I do realize that it is earthed for a short time. What difference does it make? Thank you

I found out that Power of an electrical circuit will be equal to the work done divided by the time T for which the power by the cell or battery is exerting to keep a potential difference V in the circuit for a charge Q. Hence, Power= Voltage*Charge/time Which then can be written as: Power=...

A 2.53*10^(-6) C charged particle with kinetic energy of 0.0929 J is fired into a uniform magnetic field of magnitude 0.147 T. If the particle moves in a circular path of radius 3.38 m, determine its mass in kg. (answer should be within 2*10^-14 kg) The formula r=mv/qb comes to mind where r is...

Homework Statement Three capacitors are connected in series, C1 = 4.5 mF, C2 = 7.5 mF, and C3 = 10 mF, and connected to a 150V d.c. supply. Calculate: (a) the total capacitance...

I have a hard time comprehending excess charge in capacitor plates. Let's say we have two identical capacitor and we charged them to identical amount of charge. Next we connect them in series by opposite sign electrodes and we get double the voltage on the open ends. Now a single capacitor has...

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...