What is Charge: Definition and 1000 Discussions

Does the Earth have a charge? so magnetic field? Is there a function to its distribution on the Earth surface? If there's a free charge on the air will it effect by it?

Homework Statement The charge of uniform density 50 nC/m3 is distributed throughout the inside of a long nonconducting cylindrical rod (radius = 5.0 cm). Determine the magnitude of the potential difference of point A (2.0 cm from the axis of the rod) and point B (4.0 cm from the axis). a . 2.7...

Homework Statement A charge Q is uniformly distributed along the x-axis from x = a to x = b. If Q = 45 nC, a = –3.0 m, and b = 2.0 m, what is the electric potential (relative to zero at infinity) at the point, x = 8.0 m, on the x axis? a . 71 V b. 60 V c. 49 V <-- correct answer d. 82 V...

Homework Statement A charge of +3.0 μC is distributed uniformly along the circumference of a circle with a radius of 20 cm. How much external energy is required to bring a charge of 25μC from infinity to the centre of the circle? a . 5.4 J b. 3.4 J <- answer c. 4.3 J d. 2.7 J e. 6.8 J=...

Homework Statement A charge q is kept at distance d from center of grounded conducting sphere of radius R. Find V everywhere outside. Homework Equations V = k*q/r Cosine Law. The Attempt at a Solution [/B] What do I do with the theta? And how would I analytically find out what Q and b...

Homework Statement The solution to this problem is B, and I was able to get the answer by calculating the total potential at ##r = 2a##, however, what I don't seem to understand is why must the voltage be calculated at ##r=2a## but not ##r=3a##. Homework Equations ##V(r) = - \int_a^b E(r)...

Homework Statement Imagine having a conducting sphere with free charge ##Q## surrounded by a spherical shell filled with a dielectric and then a conducting spherical shell with no free net charge. I want to find out the charge induced on the spherical conducting shell by the sphere or by the...

If we have a point charge of significant value, would osciloscope measure voltage if we just point the electrodes in two diffrent point in space?

Homework Statement Hi. in my problem there is an infinite half cylinder uniformly charged with ρ. What is the force is the cylinder is making on a test charge on a charge located on the position that is shown on the following picture: Homework Equations ∫qdQ/(r2) The Attempt at a Solution Well...

Homework Statement Homework Equations The Attempt at a Solution I'm sure my solution is wrong because of Φ(z=0) ≠ 0 I searched the internet for a similar problem but I couldn't. Any help will be appreciated.

Two infinite conducting plates 1 and 2 are separated by a distance l. A point charge q is located between the plates at a distance x from plate 1. Find the charges induced on each plate. Many of the places this problem has been solved by considering an infinitely large plate in place of the...

We all know a moving charge generates a magnetic field. A moving charge also generates a displacement current ∂E/∂t. Is the magnetic field generated entirely due to the presence of the displacement current, or is there an independent, separate effect which contributes to the magnetic field?

I have been struggling to figure this question out lately and could use some help setting it up correctly. As shown in the figure, V = 9.0 V, C1 = C2 = 27.2 μF, and C3 = C4 = 13.6 μF. What is the charge on capacitor 4? I have tried using the summation of charges and then multiplying by the...

Please help me. How many times I can charge my 5000mah mobile from 12 volt 7ah battery. I will use dc mobile charger.

Assuming the point charge lies at the origin, what is the electric field at the origin? Zero or undefined?

Homework Statement Find induced charge density in the classic image problem. Sorry, I uploaded my work in form of an image instead of typing. I have tried to use polar coordinates to solve this. But i must have done something wrong. Please help me find the mistake.

Hej Guys, Did anyone see anywhere an equation to this? If nothing else then a loading time formula for solenoid would do. Thank you!

Given a representation of a Lie Group, is there a equivalence between possible electric charges and projections of the roots? For instance, in the standard model Q is a sum of hypercharge Y plus SU(2) charge T, but both Y and T are projectors in root space, and so a linear combination is. But I...

Is there a difference between the meaning of charge conjugation in Relativistic Quantum Mechanics and its meaning in Quantum Field Theory? In chapter 4.7.5 of "Thomson Modern Particle Physics" the charge conjugation operator is derived without changing the electromagnetic field Aμ. This...

In the context of SM (##SU(3)_C\otimes SU(2)_L\otimes U(1)_Y##) the charge operator is ##Q_{SM} = T_3 + \frac{Y}{2}\mathbb{I}_2## and gives us the fermions charges. Here ##T_3=\frac{1}{2}\sigma_3## is the third ##SU(2)## generator. For example, assuming ##Y=-1## for the left lepton doublet...

Homework Statement A charge q1 is at rest at the origin, and a charge q2 moves with speed βc in the x-direction, along the line z = b. For what angle θ shown in the figure will the horizontal component of the force on q1 be maximum? What is θ in the β ≈ 1 and β ≈ 0 limits? (see image) Homework...

How can we calculate the magnetic field of moving charge by the Maxwell equation ##\nabla \times H=J+\frac {\partial D} {\partial t}##? I mean which term, ##J## or ##\frac {\partial D} {\partial t}##, should be taken into account in calculations? The first, second, or both? Can we deal with the...

Homework Statement The figure shows a closed Gaussian surface in the shape of a cube of edge length 3.20 m. It lies in a region where the electric field is given by E=(1.65x+2.86)i + 4.39j + 5.47k N/C, with x in meters. What is the net charge contained by the cube? Homework Equations net...

Homework Statement "A rod of length L lies along the x-axis with its left end at the origin. It has a non-uniform charge density λ=αx where α is a positive constant. a) What are the units of α? b) Calculate the electric potential at A. Homework Equations Linear charge density: λ = Q/L where Q...

Homework Statement For a configuration of charges and currents confined within a volume ##V##, show that $$\int_V \mathbf J d \tau = \frac {d \mathbf p}{dt}$$ where ##\mathbf p## is the total dipole moment. Homework Equations ... The Attempt at a Solution I have one question: since the...

I'm calculating current through a resistor by measuring a single current pulse, integrating it and multiplying it with its frequency. This would correspond to calculating an arithmetic mean. I also tried calculating RMS of this waveform, using GNU Octave, and was a bit surprised by the...

Homework Statement Find the electric potential of an infinitely long cylinder shell of radius ##R## whose walls are grounded, when in its interior a line charge, parallel to the cylinder, is placed at ##r=a## (with ##a<R##) and that has a lineal charge density ##\lambda##. Homework Equations...

Homework Statement A cork ball is suspended at an angle from the vertical of a fixed cork ball below. The mass of the suspended ball is 1.5x10^-4 kg. The length of the suspension thread is .1m. The fixed ball is located .1m directly below the point of suspension of the suspended ball. Assume...

Homework Statement What is the potential at the center of the sphere relative to infinity? The sphere is dielectric with uniform - charge on the surface of the sphere. Homework Equations ##k=\frac {1}{4\pi\epsilon_0}## ##V=\frac {KQ}{r}## The Attempt at a Solution If the distance r=0 it would...

Homework Statement There's a thin, straight, infinite wire conducting alternating current: $$I(t) = I_{0}\exp(-\kappa t^2),$$ where ##\kappa > 0##. Calculate the force exerted on point charge ##q## that is located in distance ##\rho## from the wire. Consider relativistic effects. Homework...

Does anybody know if there is an analytical expression for the electrostatic potential produced by a charge distribution confined to a double cone shaped region. Think of a beam of charged particles converging to a focus and then diverging again. The total charge in each thin, cross-sectional...

Homework Statement A charge q is placed at one corner of a cube. What is the value of the flux of the charge's electric field through one of its faces? Homework Equations The flux surface integral of an electric field is equal to the value of the charge enclosed divided by the epsilon_naught...

Hi everyone, this is my first thread! I am currently undergoing a personal investigation that is based on one of the factors which effect the splitting of d orbitals in central metal ion by the charge density of ligands (in a complex ion). However, recently I got stumped by trying to...

Consider a very simple idealized circuit, with a constant voltage emf, perfectly conducting wires and a resistor all in series. There is a potential drop across the resistor, given by Ohm's law: ##V = -IR##. I have read on the Internet that many people say that the potential drop is caused by a...

Homework Statement Consider a charged body of finite size, (\rho=0 outside a bounded region V). \vec{E} is the electric field produced by the body. Suppose \vec{E} \rightarrow 0 at infinity. Show that the total self-force is zero: \int_V \rho \vec{E} dV = \vec{0}, i.e. the charged body does not...

Homework Statement link: https://ibb.co/Xy9s6DR What is the magnitude of this force? Homework Equations Coulomb's Law Trig equations The Attempt at a Solution (.05 m)xcos(60)=0.025m (the distance between the two known charges) F(between the two known...

Homework Statement Homework Equations While solving this problem at r >>a ,the corresponding potential due to the dipole is kpcosθ/r2(potential due a dipole) where k is the electrostatic constt. ...(1) If σ(θ) is the surface charge density induced due to external electric field. then the...

Homework Statement [/B]Homework Equations [/B] ∫Dperpendiculards=qenclosed freecharge D=ε0E+P The Attempt at a Solution D1+D2=q/2πr2 at a distance r from the centre How to find D2 which is at the lower boundary e.g inside the dielectric??

Does The Presence of Charge Add To Relativistic Mass-Energy, or does it take two particles attracting or repelling one another to generate charge-related mass-energy?

Homework Statement You make repeated measurements of the electric field ##\vec E## due to a distant charge, and you find it is constant in magnitude and direction. At time ##t=0## your partner moves the charge. The electric field doesn't change for a while, but at time ##t=24## ns you observe a...

Homework Statement When a point charge is positioned at the origin = 0 in an isotropic material, a separation of charge occurs around it, the Coulomb field of the point charge is screened, and the electrostatic potential takes the form \phi(r) = \frac{A}{r} \exp\left( -\frac{r}{\lambda}...

It is stated that a Black hole has only mass, angular momentum and charge for properties, but since it is black ie no light escapes its event horizon and charge E/M is related (same speed) as light (photons), how can unbalanced charge be detected? And since many Black holes have electron...

Two identical metalic spherical conductor of radii ##R## are at a distance ##d## apart.One of the conductor has charge ##Q## while the another one is neutral.What will be the induced charge on the other conductor ? If we put an image charge ##q## inside the neutral one. Then the potential at...

Homework Statement A charged rod of charge 'q' is at a distance 'd' from a perfect conductor as shown below. What's the total surface charge on the conductor? 2. Homework Equations I tried to solve this without equations. The Attempt at a Solution [/B] Basically, as long as there is E field...

Dear colleagues I have this problem which I don't understand from where they got the solution I tried to solve it with slot of methods with the same answer which not the stated answer. A point charge (q) is located a distance (b) from a grounded conducting sphere with radius (a) show that the...

Many times, the charge carrier density of a material is determined from a Hall effect experiment, from ##R_H=1/(ne)## (SI units). Where ##R_H## is determined from a measured voltage and other controllable parameters. As far as I know, this simple formula comes from the obsolete Drude's model...

Hi there, Does anyone know of a machine/equipment/technology, etc. that allows a person to give charges (Coulombs) to conductors in a measurable way? I've rubbed a ton of plastic rods with fur but that's not too measurable. The Van De Graaff is overkill or it if I try to connect alligator clips...

Hello! When calculating the Hamiltonian operator in QED, in terms of creation and annihilation operators, we obtain an infinite term, which is considered irrelevant for most part (beside some renormalization problems) because we usually care about the difference in energies, so that would be...

Homework Statement A wire carrying a current I in the positive x direction is located along the x axis. The wire is of finite length and is located between x = -L and x = L. Find the magnetic field at a field point located a distance a away from the wire. Homework Equations Biot-Savart law...

Homework Statement A charge Q is uniformly distributed throughout a nonconducting sphere of radius R. Write the expression of the charge density in the sphere? Homework Equations Charge density ρ=dQ/dV Gauss's Law ∫EdA = E(4ϖr^2) The Attempt at a Solution If Q is uniform then ρ=Q/dV and the...