Charge Definition and 1000 Threads

So far I have came to know that when a charge is accelerated the electric field magnitude around the charge changes and the effect is not felt instantaneously. The change in magnitudes of electric and magnetic field travels outwards at speed of light creating the so called EM wave. So the EM...

Homework Statement It is known that the potencial is given as V = 80 ρ0.6 volts. Assuming free space conditions, find a) E, b) the volume charge density at ρ=0.5 m and c) the total charge lying withing the closed surface ρ=0.6, 0<z<1 Homework Equations E[/B]=-∇VThe Attempt at a Solution (this...

My question is, Why do we use q=1.6*10^-19 C rather than -1.6*10^-19 C, for the charge on an electron in most of the equations?

Can Kaluza-Klein theory accommodate magnetic charge? If so is there a simple geometric difference between electric and magnetic charge in such a theory? Thanks!

Hi. A student wishes to test gravitational time dilation near a black hole within her lifetime, so she travels to a location where a black hole is said to reside and parks her ship at distance where she is not affected by the hole's time dilation effects. She then fires a tethered capsule...

Hello, Given a simple electric circuit like the one below (taken from Wikipedia) If we were to start from tracking all the forces acting on each individual free electron in the circuit, would it be possible to eventually find all the currents and voltages acting in the circuit? Probably a...

Homework Statement A point charge of 5.6 microcoulombs is placed at the origin (x=0) of a coordinate system, and another charge of -1.9 microcouloumbs is placed on the x-axis at .29m. Where on the axis can a third charge be placed so that it experiences no charge? q1= 5.6 E-6 q2= -1.9 E-6 d=...

Light is an electromagnetic wave and to be so it needs an oscillating electric field, so only charges that undergoes harmonic motion shold be able to generate light is that right? And if that's right how can an electron that goes form an excited state to a lower one emit a photon? It wasn't...

Homework Statement This is more of a general question, but a simple example would be find the force on a test charge q at the center of a ring of charge with a total charge Q and a charge distribution given as λ(θ) =ksin(θ) where θ is measured clockwise with respect to the positive x-axis. The...

In the situation consisting of a steady current of 1A in an arbitrary closed path, what would the consequences be for the electric field if the drift velocity was non-uniform along the path due to non-uniform carrier density? This would be a case of a "uniform" 1 amp, but where the charge...

In any simple carboxylic acid there are two oxygen atoms then i have a confusion that which oxygen has more negative charge on it or which one has the most electron density on it?

I understand what we classically know as the charge of a particle is actually the parameter of the local phase symmetry of the field the particle belongs to, the Noether current of which permits its coupling to the electromagnetic field. But when a field has phase symmetry it is symmetric under...

I am having a hard time understanding flat band voltage in MOS capacitor. Please see the picture below about MOS capacitor. Q0 is a fixed effective charge at the surface between oxide and semiconductor and it is positive here. The voltage across the oxide caused by the fixed charge ψox =...

Homework Statement An insulator is in the shape of a spherical shell. The insulator is defined by an inner radius a = 4 cm and an outer radius b = 6 cm and carries a total charge of Q = + 9 C (1 C = 10-6 C). You may assume that the charge is distributed uniformly throughout the volume of the...

Formula for Electrostatic Potential due to a point charge is V=1/4π∈ Q1 Q2/r This implies that at r=0 value of the potential should be infinity. Is it True. If that is the case then how we say the terminals of a battery having positive and negative charge are having definite value of...

Homework Statement Is it possible to introduce local charge on a conductor? Homework Equations - The Attempt at a Solution I know that electrons can move freely from atom to atom in the conductor, so if you introduce excess electrons to the conductor, they'll spread out and there won't be a...

Greetings, There seems to be a supposition in astronomy that charged black holes are uncommon. Is this assertion well supported? According to a paper I found by Briet and Hobill, if you look at gravitational lensing alone charged black holes look just like regular black holes, but with a mass...

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...