Charge Definition and 1000 Threads

I'm working through Griffiths EM 3rd ed. in section 2.4.2 (point charge distribution) and 2.4.3 (continuous charge distribution). I understand from the section on point charge distributions that when we add up all the work (excluding the work necessary in creating the charge itself), one clever...

I know how the answer is C, since E=F/q and F=ma=mg. However, I am a bit confused as to why my other method doesn't work. I thought that since the droplets are falling at a constant velocity, there is not net force, so according to E=F/q the electric field must be zero then? This seems like a...

Hello, Let's imagine we have an infinite plane (or large enough compared to the region of interest and measurements) pierced in normal direction by magnetic field B which is uniformly distributed but time varying. For the sake of simplicity we'll presume the magnetic induction is linearly (and...

Two identical conducting spheres A and B carry equal charge. They are separated by a distance much larger than their diameters. A third identical conducting sphere C is uncharged. Sphere C isfirst touched to A, then to B, and finally removed. As a result, the electrostatic force between A and B...

Double integration maybe?? I calculated potential due to shell on plate's center but not on other points on it's surface.

Why is angular momentum conserved for a charge in an electric field?

My Textbook says this is the formula to find energy values for electron shells: $$E_{mol of electrons} = \frac{-1312kJ}{n^2}$$ where $n$ is in electron shell number But when we divide by 1 mol to get the energy value for each electron we get $$E_{electron} = \frac{-2.178 \cdot 10^{-18}}{n^2}...

Where should I start?

Hello, there are a couple things about magnetism that I do not understand. 1. Why didn't we define the magnetic field to be in the directions of the force? This isn't really a technical question, I am just more curious about why it is this way. The way I was thinking of it, the math seems to...

I want to charge a 52V 12ah lipo battery directly using 2x 36 cell, 120 watt max solar panels in the most efficient way possible. My current plan is to wire the two solar panels in series to produce one effective 72 cell, 240 watt panel. The peak output voltage is 34 volts at 14 amps. The...

I was recently seeing videos on standard model of particle physics and something occurred to me that ,Higgs field gives mass to elementary particles ,this gives reason for one property of matter that is mass. Why not a field that gives elementary particles a charge ? After all their are two...

I'm trying to get the Electric Field of a Thin spherical shell along $$ \hat z $$ axis. In this problem I've got a charge/area density: σ(θ)=σ0⋅cos(θ)σ(θ)=σ0⋅cos(θ). θ∈[0,π]θ∈[0,π] (theta is the polar angle)Can you please help me with how can I know the area element? thanks.

Hi. In a current carrying conductor because of special relativity amount of protons and electrons differ so we get an electric field or as we call it magnetic field. So if magnetic field is just an electric field how is it that the charge has to move so that magnetic field would exert a force on...

Hi. Need help with physics homework. I was able to separate each term and find sigma from the second term and possibly lambda from the first term. Not sure how to approach the third term. (attached attempt at question)

Hi. Need help with physics homework. I was able to separate each term and find sigma from the second term and possibly lambda from the first term. Not sure how to approach the third term. (IMAGE ATTACHED)

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...