What is Charge: Definition and 1000 Discussions

This is a question that is vaguely related to coursework but is more for curiosity. Lets say there are two spheres joined by a thin wire in the presence of an electric field: Assume the conductors initially have no charge. Now I am pretty sure without the wire, the charge distribution would...

Homework Statement . Homework Statement If the electric field does negative work on a negative charge as the charge undergoes a displacement from position a to b within an electric field then the electrical potential energy is? ANSWER: positive Homework Equations none The Attempt at a...

Hi! It has been explained to me in another thread of mine that there actually can be lightning/thunder within a cloud. My question now is how there can be such high charge gradients within a cloud that this can happen and of what types of ions and electrons there is and how they have emerged...

Homework Statement A charge 2Q is placed a distance 'd' from charge 4Q. A third charge 'q' is placed 3m from charge 2Q directly on the line between charges 2Q and 4Q. Find d and q such that the force between charges 2Q and 4Q is equal to 0. Homework Equations Coulomb's law: f = k(|q1q2|)/r2...

Is it right to say that 'modern physics has no deep explanation of the nature of charge' in electrons and protons?

As per the Gauss Law , Net Flux Electric Field through a closed Surface (Gaussian Surface) is zero if no charge is enclosed. As per the definition of the Electrical Flux = Electrical Field Intensity dot product Area Vector i.e. Closed Integral of E.S If Electrical Flux is zero then as per the...

Homework Statement Homework Equations coulomb's law The Attempt at a Solution Hi everyone. I understand their approach with the integration to find the amount of work that "a person" would have to do to bring the charge q3 from infinity to its current position. I understand...

When calculating the electric field from a point above a line of charge using coulomb's law, the integral that comes up is of the form \int { \frac { dx }{ { x }^{ 2 }+{ a }^{ 2 } } } . But if the point we were asked for is right in the middle, the horizontal (cosine) components cancel out...

Need some information about electret. Is it possible to charge a metal plate electostatically using electrets. will electrets attract neutral charged things, like glass rod attracting paper pieces after rubbing with wool ?

Hi Everyone, I'm trying to justify to myself why |F(a)| > |F(b)| > |F(c)| I think I can see why |F(b)| > |F(c)| due to special relativity case c observed from the charges point of view would observe the charges closer due to lorentz contraction. As the charge is invariant would result in...

"Classic" EM is symmetric against electric and magnetic fields/charges (except magnetic charges are not observed in reality, but this is another story). Still, magnetic field is pseudovector and magnetic charge is pseudoscalar. I suspect where it comes from in classic EM, but I wonder about QFT...

1. Homework Statement final charge on 3 microF be q1, on 2 microF be q2 and on 1.5 microF be q3 Intial charge on 3 microF is 360 microC and intial charge on 2 microC is 300 microF Homework Equations how the charge conservation takes place at the three junctions in the circuit The Attempt...

Homework Statement Two point charges ##Q_1 = 9 \mu##C and ##Q_2 = -16 \mu##C are fixed in space on a distance r=7cm. At what distane ##x_1## from the first charge, and ##x_2## from the second charge, should we place the third charge ##Q_3## so that net force on ##Q_3## is zero? make a sketch...

Why does the potential energy of a system of two charged particles decrease as the distance between them increases? It seems that the PE should increase, as in U=mgh; as h increases, the PE increases. Why does this not occur in electrical potential energy, and in the gravitational potential...

Suppose some charge and current config is present which at time t produces fields E and B. In the next instant dt the charges move around a bit. Work done on the charge q F.dl=q(E+v×B).vdt=qE.vdt dW/dt= qE.v Now the question is q has also contribution in the field E. How the charge is exerting...

Homework Statement (Not for homework/assignment. Just doing problems for practice) This is from Griffiths Introduction to Electrodynamics, 4th edition, p.112 Problem 2.60 " A point charge q is at the centre of an uncharged spherical conducting shell of inner radius a and outer radius b...

Homework Statement car's battery has voltage (E) 11,5 volts and internal resistance of 0,040 ohms. battery's charge is 20 amperehours (20 Ah) How many ignition attempts of the car can be made, when the charge can be allowed to fall to 15 amperehours. One attempt of at engine ignition...

Homework Statement An electric charge Q is uniformly distributed along a thin circular wire situated in the z = 0 plane at x2 + y2 = R2 . Determine the electrostatic potential at the point (0, 0, D). Homework EquationsThe Attempt at a Solution I figured the only components that mattered would...

Hi, I am a high school physics student and the only ways we learned to calculate the magnitude of a magnetic force involved a moving charge or current in a wire. As a result I have wondered how a bar magnetic magnet may exert a force on a piece of iron, since there is no clear movement of charge...

Homework Statement edit: I had put this in the calculus section because it was a problem from Stewart but I guess it's closer to a physics problem considering the use of Gauss's Law. My apologies for any confusion this my [/B] I've been trying to do this problem without making use of the...

Homework Statement A slab of material has parallel faces. One coincides with the xy plane (z = 0), while the other is given by z = zt . The material has a nonuniform polarization P = P(1 + αz)zˆ where P and α are constants. Fin the volume and surface densities of bound charges[/B] The Attempt...

My teacher posted on his website, Lewis structures of different compounds. One of them were N3- Why isn't there a dipole moment arrow pointing from the central atom to the other Nitrogen? Does the arrow only point from neutral atom to negatively charged atom?

The Earth has a net negative charge whilst the Ionosphere has a net positive charge, this has been known for well over a hundred years now. My question is about the negative charge of the Earth, are the free electrons on the Earth's surface stationary? are they whizzing around in the Earth in...

Homework Statement A particle with charge ##e## and position vector ##\vec{r}## (relative to some frame, S) moves with constant velocity ##\vec{v}##. A second charge ##e'## is moving with the same velocity ##\vec{v}## through the field generated by ##e##. If ##\vec{d}## is a vector from ##e##...

Ques: If infinite number of charges placed along x-axis .At x=1, 1μC , x=2, 2μC, x=3, 3μC so on. Find the net force on charge 1μC placed at origin.Formula used (1/4πε)*q1*q2/r² Solved from this formula but stuck in a series

Homework Statement At t = 0, the charge stored on the capacitor plates is maximum in an oscillating series RLC circuit. At what time will the maximum possible energy that can be stored in the capacitor fall to one-eighth of its initial value if R = 7.20 Ω and L = 21.0 H? The differential...

Homework Statement When an instable atom emits alpha or beta particles. Doesn't the overal electrical charge of the remaining atom change? For example when an atom emits alpha decay, a helium core is emitted, this results in the lose of two protons (forthe radiating atom). But doens't this mean...

Homework Statement 1. Homework Statement [/B] Prove the potential energy of interaction between an electric charge ##q## moving with velocity ##\vec{v}## and an electromagnetic field with potentials ##V## and ##\vec{A}## is given by ##U = qV-q \vec{v} \cdot \vec{A}## Homework Equations...

Homework Statement Consider a long, cylindrical charge distribution of radius R with uniform charge density ρ. a) Using Gauss’s law, find the electric field at distance r from the axis, where r < R b) Using Gauss’s law, find the electric field at distance r from the axis, where r > R...

A battery has an Emf 6 Volts. It is completely discharged. It is charged by maintaining a potential difference of 9 Volts across it. If the internal resistance of the discharged battery is 10 ohms, find the current through the battery, just after the connections are made. My textbook says that...

I came upon this page that provides the answer: http://farside.ph.utexas.edu/teaching/em/lectures/node125.html But I can't figure out what gamma(u) is. Could anyone help?

Homework Statement If linear charge density is equal to 1micro coulomb per meter, then what is the electric field intensity at O? Homework EquationsThe Attempt at a Solution The electric fields due to the two straight lines should cancel out.. But how to progress further? Please let me know...

So I was posting questions in someones homework help and I thought I'd create my own thread instead. https://www.physicsforums.com/index.php?threads/868492/ Now in coulombs equation you multiply the coulombs (Q1×Q2) Ujjwal (OP in other thread) was using 2 balls charged at 2 and 3 coulombs in...

Hello.. i just saw this amazing Forum and wanted to contribute, so here is my first question and i hope i get an answer x.d I was told that at electrostatic equilibrium, the electric field inside a conducting sphere will be ZERO, How can i charge thissphere from the inside, so the Electric...

Hi everyone, I am self-studying Electricity and Magnetism. I have a good grasp in Calculus, but still I am confused on how to figure out volumes of arbitrary figures(rest is easy). I know it's a bit silly. I mean how do we know how to choose a figure (like in case of hemisphere, you imagine...

Homework Statement A thin insulating rod with charge density lambda=+5nC/m is arranged inside a thin conducting cylindrical shell of radius r =3 cm. The rod and the shell are on the same axis, and infinite in length. What is electric field at point p? 6cm from the central axis. Homework...

What statement about magnetic fields interacting with a moving charge is correct? A) Magnetic fields can’t change the direction of motion of a moving charge. B) Magnetic fields can do work on a moving charge. C) Magnetic fields can accelerate a moving charge. D) The force on a moving charge in a...

Hi, In my notes it says that SU(5) operates on a five component vector. Fine. But the example given is (d d d e v) ie. electron, neutrino and 3 down quarks (one for each colour) it says this explains why the proton charge is the equal and opposite to the electrons but why? A proton is uud...

They say that an electron accelerating radiates and loses energy, and that is one of the reasons why an electron cannot orbit a nucleus: - 1) does a charge accelerating in a straight line radiate, and what is the rate of radiation? do we have to supply extra Ke (apart from m/2 v^2) when we...

I have several problems regarding this/these topics. Is anyone available to tutor me right now? Thank you.

Hello, I'm posting the first time on this forum. I want to create a robot controlled by an Arduino which is able to make a touch signal without using a mechanic arm or finger ( here is a robot with the same goal but using an arm video). I want to take the electrical approach. A modern...

where are the charge =0? please help...no idea how to do

Homework Statement A thin rod of length 2L has a linear charge density that isλ0 at the left end but decreases linearly with distance going from left to right in such a way that the charge on the entire rod is zero. Given E = −kλ0/L(d/(L−d)−ln(d−L)+d/(L+d)+ln(L+d)) for a point P that is...

Homework Statement A positively charged particle initially at rest on the ground accelerates upward to 180 m/s in 2.70 s .The particle has a charge-to-mass ratio of 0.100 C/kg and the electric field in this region is constant and uniform. What are the magnitude and direction of the electric...

- David J Griffiths But how s it valid for some conductor like →

Homework Statement A positive point charge q is located off-center inside a conducting spherical shell.We know from Gauss’s law that the total charge on the inner surface of the shell is −q. Is the surface charge density negative over the entire inner surface? Or can it be positive on the far...

my understanding of beta radiation is that an up quark in a proton changes to a down quark, forming a neutron and emitting an electron as the result of the change in charge. My questions are, 1. Why does the quark change? 2. How does it change and how does it change charge?

Hello! Double heterostructures are used in LEDs and lasers to provide both the confinement of the charge carriers and the confinement of the generated light. This image is a comparison between a homojunction and a heterojunction. As regards the unbiased junctions, when the n region and the p...

Is there any easy way to determine the charge on a van de graaff generator based on the voltage?

Today my prof said that for a point charge the force is proportional to 1/r^2. For a line charge it is proportional to 1/r. For a sheet charge it is a constant and for a volume it is proportional to r. He also did some derivations but I don't see how this can be. For example for a sheet charge...