What is Charge: Definition and 1000 Discussions

Homework Statement q=1.602*10^-19 point 1 L=1mm=r1 v=1.1*10^6 at point 2 F=1.44*10^-12 at point 1 Homework Equations E=(1/4πε)*(q/r) ΔV=∫E*dr=(1/4πε)*q∫(1/r)=(1/4πε)*q*ln (r2/r1) ΔU=ΔK=mv^2/2 ΔK=mv^2/2=ΔV*q=q*(1/4πε)*Q*(ln(r2/r1))...

Say, we have two particles of equal and opposite charge in an isolated system in which we neglect gravity. The energy of particle 1 is: E1 = U1 + T1 Where U1 is electrostatic potential energy and T1 is the kinetic energy of particle 1. The energy of particle 2 is: E2 = U2 + T2 Where U2 is...

Homework Statement Homework Equations ##q = CE(1 - e^{-t/RC})##The Attempt at a Solution I assumed that, since the problem specifies that sufficient time has passed, it meant to say that enough time passed. thus making the exponential term in the equation go down to 0, and the charge in the...

Homework Statement Hello, this is more of a conceptual question than a concrete homework assignment question. I'm learning about Gauss's law and the Prof did an exercise on a sphere with uniform charge distribution, where he found E(r). The trick was, that E(r) was constant over the Gaussian...

Homework Statement Given that we have q1 = -4nC on the y-axis at y=0.60m. q2 on the y-axis at y= -1.20m. What must be the sign and magnitude of q2 be for the net electric field at the origin to be: a. Zero b. 50 N/C Homework Equations E=KQ/R2 The Attempt at a Solution I used: ET = E1 + E2...

Homework Statement Homework Equations Circuit Equations. ##U_C=Q^2\2C## ##U_L=Li^2\2## The Attempt at a Solution For (a) I said ##100J## .But I think it might be ##200J## too.Here what I did; ##U_t=Q^2\2C## and I put ##Q=0.1C## and we know ##C##.Here I...

So I am aware the charge conjugation operator changes the sign of all internal quantum numbers. But I was wondering how it acts on a state such as ## \left|\pi^{+} \pi^{-} \right>## when the individual ##\pi's## are not eigenstates of C. I believe the combination of the ##\pi's## has eigenvalue...

Homework Statement We have a spehere of radius ##r_1## and on of ##r_2## far away from each other. The first sphere has a charge ##Q##. What is the change in electro static energy when they are connected together? Homework Equations Potential of a charged sphere: ## V = \frac{Q}{4\pi\epsilon_0...

Homework Statement We have two metal spheres of radii ##R_1## and ##R_2## placed far apart. Given total amount of of charge ##Q## to distributed between the two spheres, how should you do it so that the potential of given distribution is as small as possible. Homework EquationsThe Attempt at a...

Some things I did not get are, 1): In the third para, it is said that potential approaches ##\infty## at ##Q##, why ? 2): In last para, The z component of field by ##Q## is said to be ##-Qh/(r^2 + h^2)^{3/2}##, Why ? should not it be ##+Q## not ##-Q## has the charge itself is positive. 3): I...

Homework Statement Charge is distributed uniformly over a large square plane of side l, as shown in the figure below. The charge per unit area is σ. Determine the electric field at a point P a distance z above the center of the plane, in the limit l -> infinity.. Homework Equations please...

Homework Statement Two 3.0-cm-diameter aluminum electrodes are spaced 0.50 mm apart. The electrodes are connected to a 200 V battery. Find the capacitance of one of the spheres. Homework Equations [/B] C=QV C=ε0A/d The Attempt at a Solution [/B] I'm really not sure how to approach this...

Lets suppose we have a charge and we want to accelerate it from a point A to B and back. Does the energy requirement increases if we move the charge quicker? I can make an analogy with mass. To accelerate an object over a distance d requires energy. The objects resist to change in velocity. The...

Homework Statement The Attempt at a Solution Top left: No charge flowing through circuit b/c switch is open, not closed. Top right: No charge flowing through circuit b/c circuit does not connect positive and negative terminals Bottom left: Charge flows through circuit b/c closed loop between...

Homework Statement A uniform spherical charge density of radius R is centred at origin O. A spherical cavity of radius r and centre P is made. OP = D = R-r. If the electric field inside the cavity at position r is E(r), the correct statement is: 1)E is uniform, its magnitude is independent of r...

Homework Statement In a certain region, the electric potential due to a charge distribution is given by the equation V (x, y, z) = (3x2y2+yz3-2z3x)V0/a4 where a, x, y, and z are measured in meters and V and V0 are in volts. What is the magnitude of the electric field at the position (x, y, z)...

Homework Statement A thin disc, radius 3 cm, has a circular hole of radius 1 cm in the middle. There is a surface charge of -4 esu/##cm^2## on the disc. a) what is the potential at the centre of the hole ? b) An electron starting from rest at centre of the hole moves out along the axis. What...

Homework Statement A line charge with uniform charge distribution and linear charge density ##\lambda## lie along z-axis from ##(0,0,-d)## to ##(0,0,+d)##. Find electric field due to this charge along z, x-axis and potential at ##(0,0,2d)##, ##(\sqrt{3}d, 0,0)## and ##(3d/2, 0 , d)##...

Homework Statement Question : How much charge is stored on the capacitor C2 ? 2. Homework Equations Q = C . U The Attempt at a Solution [/B] Since Q2, the charge stored on the capacitor, is C2 . (Va - Vb) , I thought that I just had to multiply 1.0 x 60 = 60. But in fact, the expected...

From the book, I did not understand, 1. Why does fields coming inwards the sphere contradicts the Gauss law ? 2. I am unable to connect the potential picture and electric field picture. Why does the point P must have lowest or highest potential than neighbouring particles ? 3. I understand...

Hello all, As I understand (and realize when looking at my electricity bill) it seems all power utility company (in residential market) only charge for kW not kVA. But somehow I find it a bit weird when I think about it more deeply. Wouldn't it make more sense to charge for kVA ? Otherwise, it...

there is power source grounded, with electric power of 20v the negative side of the wire we connect to a pointy metalic button and the positive side of the wire we connect to a metalic conductive ring with radius of 7.5 cm as...

To make antimatter you have to change the charge of proton and electron. So how do you do it

Given a charged sphere, the electric field within it is zero at every point. Why is this? Why is not merely zero only at the center? If a sphere is conducting, then its charge is all across the surface. If electric field is inversely proportional to distance from charge squared, won't the field...

Homework Statement A charge ##Q## is distributed unifromly around a thin ring of radius ##b## which lies in ##xy## plane with its centre at the origin. Locate the point on the positive ##z## axis where the electric field is strongest ? Homework Equations The Attempt at a Solution...

Homework Statement Consider a high voltage direct power line which consist of two conductor suspended 3 meters apart. The lines are oppositely charged, If electric field halfway between them is ##15000N/C## how much is the excess positive charge on a 1 km length of positive conductor ...

While reading the book, Electricity and magnetism, the author says that electric field just outside a spherical shell is ##4\pi \sigma##, on it ##4\pi\sigma r_0^2## ,inside is ##0## and outside is ##Q/R^2##. My derivations :- For inside, ##E\Delta S = 4\pi Q = 0## since ##Q = 0##. For...

Suppose a spherical shell is kept at the orgin. Its surface charge density is ##\sigma## and radius is ##R##. I think I remember the formula for its electric potential energy is ##U = \displaystyle {Q^2 \over 2R}##. Now I want to derive it. I used ##\displaystyle U...

Hi, Let's think 2 arbitrary shape conductors with non zero charged. If these 2 conductors are closed, there will be induced charge density over surfaces of these conductors. I have not seen such an example, instead there are lots of problems which involve zero(grounded) potential case and...

It’s been a long time since I took E&M courses and even thought about these things, but a current thread has led me to question the location of excess charge on a conducting shell. Given that there are two surfaces to which charge can move, why doesn’t some charge also locate on the inner...

Homework Statement Two positive point charges, A and B are 6m apart. The electric field intensity at point C, midway between the two charges is 5 N/C directed towards B and the potential at the same point is 45V. Find the magnitude of A and the magnitude of B. Homework Equations E = kQ/r2 The...

I've got confused over a topic in my physics textbook (Fundamentals of Physics). The textbook says if a charged particle is enclosed by a shell of uniform charge, there is no electrostatic force on the particle from the shell. I don't firmly get this, as the book uses a confusing reasoning for...

Would you be better off standing your ground? I don't actually know how massive a bull is but let's say about 1,700 kg. It's coming at you with a velocity of 16 m/s. You got a human who is a decent 93 kg and runs in the opposite direction at 12.517 m/s (he's an olympian 100m runner). Would...

Why the gaussian surface is "A" instead of "2A" on the right-hand side?(the photo attached below) Due to the thickness of the sheet? I usually find that E=σ/2ϵ0 is being frequently used but we hardly use E=σ/ϵ0. When can I directly apply the equation E=σ/ϵ0 ?

Homework Statement There is a total of ##Q## charge on soap bubble of radius ##R##. What force is acting on one hemisphere by the other ? Homework Equations Electrostatic pressure is ##P_e = 2\pi \sigma^2## for a spherical shell. The Attempt at a Solution ##P_e = F/A## therefore ##F =...

Homework Statement A capacitor with a capacitance of C = 5.95×10−5 F is charged by connecting it to a 12.0 −V battery. The capacitor is then disconnected from the battery and connected across an inductor with an inductance of L = 1.50 H . What is the charge on the capacitor after a time...

What equation in QM show us that symmetry in quantum-mechanical phase implies charge conservation?

Homework Statement You dope an $n$-type substrate at time ##t=0## with electrons and holes around the points: ##\vec{r}_{0,c}## and ##\vec{r}_{0,v}## respectively. The initial densities' distributions are: $$\Delta n (\vec{r},t=0) = \frac{\Delta N_0}{(2\pi...

Is there anyway to detect the Earth's magnetic field without a compass? or putting it differently, Is there anyway to detect an electric field without bringing a charged particle in proximity of the field?

The circuit is intended to control the charging of a 12v 7ah battery by a 10w, 24v volt solar panel.

Homework Statement Hi guys, I hope you can help me with this problem, because I do not have any idea and I could not find anything that could help me, thank you in advance! Draw the electric field lines due to a punctual charge Q immersed in a dielectric medium with constant K1. Q is separated...

Homework Statement I'm having a bit of trouble with this problem: "A spherical ball of charge has radius R and total charge Q. The electric field strength inside the ball (r≤R) is E(r)=r^4Emax/R^4. a. What is Emax in terms of Q and R? b. Find an expression for the volume charge density ρ(r)...

The question asks to find total charge in a region given x has lower bound 0 - upper bound 5 , y has lower bound as 2 and upper bound as 5. Based on knowledge I have been reading throughout the chapter, I set up a double integration with those dxdy, but the results went out to be off - compared...

Take the following diagram of 4 1.5V batteries connected in series to creat and net voltage of 6V (the numbers are of no significance here). If we were to short circuit the system by connecting battery 1 to battery 4 (or run the current through a load), wouldn't there be electrons traveling...

I wonder, what would happen if you started dropping lots of electrons into an existing black hole which otherwise doesn't accrete any new matter? The charge of the black hole would build up much faster than the mass. Wouldn't its charge become so high at one point that further electrons would...

Homework Statement What collection of image charges solves the problem in above pictured ?? Homework EquationsThe Attempt at a Solution One of the image charge should be in dielectric region q'=-((e2-e1)/(e2+e1))

I have a moving charge in a generic motion, and I pick a point p, how do I get the electric field caused by the charge on point p, at any time? Can I use the coulomb definition of electric field that relates it's strenght with the Distance? Or does that law works only when the charge is static...

Homework Statement The current in a wire varies with time according to the equation I(t) = 6.00 A + (4.80 A/s)t, where t is in seconds. How many coulombs of charge pass a cross section of the wire in the time period between t = 0.00 s and 3.00 s Homework Equations I=dq/dt The Attempt at a...

Homework Statement I am trying to derive an expression for the potential of a positive point charge by bringing in another positive test charge in from infinity to a point at a distance R from the point charge. Homework Equations $$V_f - V_i = - \int \vec E \cdot d \vec r \, dr$$ The Attempt...

The intrinsic charge parity of a species is the ##\eta_C## defined in the equation $$\mathcal C |\psi \rangle = \eta_C |\psi \rangle $$ which can take on values ##\pm 1##. Since the gluon carries a colour charge, it is not an eigenstate of the C (charge conjugation) operator. 1) Why do I...