What is Charge: Definition + 1000 Threads

Chargé is a commune in the Indre-et-Loire department in central France.
Chargé is a small town near Amboise. The Rock 'in Chargé festival has revitalized the village since 2006

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1. B Some Questions about Electric Current/Capacitors to help my understanding

Q 1) In electric currents, in a battery, the positive charge starts at the negative terminal and gains energy through emf which forces the charge to go to the positive terminal of the battery, with plenty of energy. This voltage is the energy difference between the terminals. For the charges to...
2. Electric field lines outside a neutral conducting spherical shell

I'm talking about a situation like this. Ive been told that charge distribution on the inner side of the conducting material is non uniform and equal to -q. This makes perfect sense But ive also been told that the charge distribution on the outer part of the conducting material is ##uniform##...
3. A charge q approaching two stationary charges q1 and q2

I'm only confused about one part of this problem and that is setting up the conservation of energy equation. In the solution, they just wrote this: $$\frac{mv_o^2}{2} = - k \frac{q_1 q}{r} + k \frac{q_2 q}{l + r}$$ where ##r## represents the distance at which the force created by the negative...
4. Critical distance value for attractive force

On Problem 3.11 for Griffiths' Electrodynamics, there is a question that asks for the critical value between a point charge and a conducting shell, but I don't quite know what they mean by 'critical value' in this context and how I'm supposed to approach this question, the rest of the problem is...
5. Charge conservation for 3 parallel charged plates

I took a point P on the conductor with charge Q. We know that the field inside a conductor is zero in electrostatic equilibrium Therefore I took induced charge on the neutral conductor to be x and gave the respective charges to the others. On the side facing conductor with charge Q the neutral...
6. Closest distance of approach between 2 charged particles

A few hours ago, I tried solving this problem and I'm still not quite sure if I've made a mistake somewhere or perhaps the guy in the video is wrong? Anyway, here's my solution: In the problem we're given that the total kinetic energy of of these 2 charges at this instant(look at the picture)...
7. Is My Answer Correct for Calculating Average Current on a Ring?

$$I=\frac{q}{t}$$ $$=\frac{4Q}{T}$$ $$=4Qf$$ My answer is (a). Is that correct? Thanks
8. A Why do the proton and electron have equal and opposite electric charge?

The most common explanation I know is that anomaly cancelation implies the sum of electric charges of each particle must cancel generation-wise, so 3 Q(Up) + 3 Q(Down) + Q(electron) = 0, and electroweak doublets imply Q(Up) - Q(Down) = Q(neutrino) - Q(electron), so with Q(neutrino) = 0 it solves...
9. I Color charge is not scalar -- do their components have dimensions?

Color charge is not scalar. Still, do their components have dimensions (in metrological terms)?
10. I Only one type of elementary electric charge?

Is there only one type of elementary charge? The type of elemental charge that appears on particles such as electron, proton, etc. It is well known. Could there be another different type that we don't know yet?
11. The electric potential inside a conducting sphere with charge Q

If there is no field inside the conductor, how can there be electric potential? I think of potential very similar to gravity, as how much energy would be required to move a particle of mass/charge against the gravitational/electric field. If there is no field at all, how would there still be...
12. I Why charge density of moving dipole is dependent on time?

This paper aims to resolve the inconsistency between different transformation equations by expressing the electric current created by a moving electric dipole as the sum of polarization and magnetization currents and calculating the resulting magnetic field. Here they take charge density to be...
13. Coulomb's law and energy - potential energy

I know that the formula qqk/r applies to a system (two charges), but where is the flaw in my derivation? Thanks!
14. B Conservation of charge in a nuclear reaction

Conservation of charge: The sum of the charges on all the particles before and after a reaction are the same I was considering this reaction: n + 3 He → 3 H + p + 0,764 MeV Making the charge balance I have: 0 + 0 (2protons + 2 electrons) → 0 (1proton + 1electron) + 1 (proton) There is...
15. Electromagnetism problem: Merging of 2 charged drops of mercury

I originally thought that this problem was simple, and it still seems like it is, but there are conflicting solutions and I don't know which is correct. So I first solved for R1 and R2 using V=kQ/r where R1 is 0.514 and R2 is 0.54. My original thought was volume is conserved so V1 + V2 = V3 and...
16. Final Charge of a Capacitor in a Circuit with Capacitors and Resistors

I had two trains of thought. One is that the capacitor will fully charge when t = infinity, so when you plug t = infinity into the equation of charge as a function of time you get 1.68E-4, which you also could've gotten from Q = CΔV where ΔV = 42V. My other train of thought was that when t =...
17. Why Is the Electric Potential the Same for Inner and Outer Semi-Circles?

I solved using the formulae listed in the relevant equations and got the right answer. However, I noticed something strange to me. The electric potential due to the inner semi-circle was equal to that due to the outer semi-circle. But based on the formula for calculating V, we notice that there...
18. A 3.5 nC charge is at the origin and a -10 nC charge is at x = 2 cm

Apparently the answer is not 2.9 cm or 7.4mm. I've looked at similar questions in this thread and solving the exact same way gives me the same answers. I set it up as (3.5/x^2)=(10/(.02+x)^2). What am I doing wrong?
19. E&M: Forces resulting from Charges at the Corners of a Cube

My first attempt at solving: I divided up the point charges based on the radius away from point A. 1 charge was s*sqrt(3) away, 3 charges were s*sqrt(2) away, and 3 charges were s away from point A. q remained constant. Therefore, my F_total was: F_total = k * [(q^2 /...
20. B Stationary charge next to a current-carrying wire

(1) https://www.youtube.com/results?search_query=relativity+and+electromagnetism (2) If I understand this correctly, then, well, shouldn't all current-carrying wires exhibit a small amount of positive charge?
21. B Can I use this method to charge a metal sphere?

Consider a metal sphere connected to one end of the battery and the other end of the battery to be connected to the ground. Does the metal sphere become electrically charged with this method?
22. I Maxwell's equations and the momentum of charge

There appears to be a conservation of charge momentum (qv) analogous to that for mass (mv) although in the case of charge it is more potential in nature. A change in the flow of charge (or current) produces changing magnetic and electrics fields according to Maxwell's equations. These in...
23. I Electrical breakdown in air in the presence of a single charge

Suppose there is an electric charge of 350 micro coulombs in space. The electric field at a distance of less than one meter will be more than 3,000,000 volts/meter considering that this field is greater than the electric breakdown of air and the charge has no place to discharge, what happens...
24. What could be draining the car battery and how can it be fixed?

Our car battery is past its warranted life by 1.5 years (it's 5 years old). It's been discharged a few times due to lights being left on overnight. We're not currently using the car because of engine issues, so it just sits in the driveway for the last few months. Last week, it was found...
25. Multipole Expansion for Two Charged Hemispheres

My thought: First of all, I find the upper hemisphere (with a total charge +Q): ##ρ(\vec r)=\frac {V} {Q}## where V is the volume of the upper hemisphere = ## \frac {2} {3} \pi R^3##. Secondly, find the lower hemisphere (with a total charge −Q): ##ρ(\vec r)=\frac {V} {Q}## where V is the volume...

I'm confused in the calculation for R/2. The author took in account that the charge will change by a factor 1/8. But how does it show that the coloumbic force will become 1/8th. The distance will also reduce by half shouldn't that also be taken into account? Or am I missing something here?
27. How to Compute charge ##Q## of a particular state in free Dirac field

suppose I should evaluate $$Qa_{p1}^{r \dagger}a_{p2}^{s \dagger} b_{p3}^{t \dagger}$$ I get lost in the commutator relation. Any help?
28. B Why is the test charge always positive?

why test charge is always positive ?
29. Describe how you could use a pith ball as an electroscope

Would it still work in a similar manner as an actual electroscope where you would charge it either positively or negatively and then observe attractive or repulsive forces or is there an easier and more efficient method?
30. Coulomb's Law Application: A charge repelling a mass on a frictionless incline

Fg = Fc Fg = 2.3g*9.8m/s^2*cos(28)=19.90N 19.90 = (8.99*10^9)*(4*10^-6)*(6*10^-6)/(r^2) 1/(r^2) = 92.23 r = 0.104m However, it's not one of the option...
31. Calculating Charge of an Electron w/ the Millikan Oil Drop Experiment

I am doing the Millikan Oil Drop experiment to determine the charge of a single electron. I have been following the lab manual provided by the manufacturer, https://hepweb.ucsd.edu/2dl/pasco/Millikans%20Oil%20Drop%20Manual%20(AP-8210).pdf. The manual defines a simple method to calculate for...
32. I How do we know that both plates of a capacitor have the same charge?

Suppose we have two conductors ( can be of different shapes) and connect them to battery. Why would equal amounts of charge appear on the two conductors?
33. M

Conventional current definition and a variation on that definition

One normally sees that the definition for conventional current as defined as the amount of positive charge that passes a point over unit time. However, why could we not define conventional current as the amount of positive unit charge that passes a point over unit time. I added in unit there...
34. Engineering Calculate time for capacitor to charge and discharge

I really don't get this one. Why do I need V? Since I didn't use it, I assume my work Is incorrect.
35. What is the source of the Kelvin Water Dropper effect?

From a classical mechanics perspective I understand the force interactions leading to the phenomenon, but from a matter perspective, what is a "positive" or "negative ly" charged water stream? Is this referring to the spontaneousH(+) + OH(- )formations?
36. What is the magnitude of the field at point R?

I've no idea how to solve this problem. The sign of the charge is not mentioned, so I'm assuming the charge is "+". The charge exerts an outward electric field. Since two lengths of the right-angle triangle are given, I use the Pythagorean to find the hypotenuse, which is the distance between q...
37. Find the magnitude of the electric field at point P

There are two identical spheres with the same charge that are the vertices of an equilateral triangle. ##+3 \mu C## will exert an outward electric field, which is drawn in the FBD below (see the attached pic), Since the horizontal force components (1x and 2x) are equal and opposite at point P...
38. Find the magnitude of the electric force from 3 charges at vertices of a cube

There are three charges with +1 μC and −1 μC, are placed at the opposite corners of a cube with edges of length 1 cm, and the distance from P to B is 1cm 2. I labeled them as A, P, and B, which is shown in the diagram below. Since we need to find the magnitude of the charge at point P and the...
39. Line of charge and conducting sphere (method of images)

I was thinking of using the sphere and point charge as an analog, but is quite diferent from what i have seen
40. Total Force on a Point Charge in Motion

As the observer is moving, there will be a magnetic force. Electric Field of the Rod = λ/2πεr r̂ Electric Force on the Point Charge = qλ/2πεr r̂ Magnetic Force on the Point Charge = q(vxB) = qvB n̂ = qv(µI/2πr) n̂ = qv(µλv/2πr) n̂ = µqλv²/2πr n̂ Total Force = Electric Force + Magnetic Force
41. B Exploring the Electric Field of a Moving Charge

How does an electric field of a moving charge, for example a moving electron, inside a wire looks like? Does it looks like this with distorted circular radial lines?
42. B How did fundamental charge thinking develop?

How did fundamental charge thinking develop?
43. Finding Current in Resistors & Charge of Capacitor

Suppose the switch has been closed for a long time so that the capacitor is fully charged and current is constant. a)Find the current in each resistor and charge Q of the capacitor. b)The switch is now opened at t=0s. Write the equation for the current for the resistor of 15kΩ as a function of...
44. Divergence of the Electric field of a point charge

Hi, unfortunately, I am not sure if I have calculated the task correctly The electric field of a point charge looks like this ##\vec{E}(\vec{r})=\frac{Q}{4 \pi \epsilon_0}\frac{\vec{r}}{|\vec{r}|^3}## I have now simply divided the electric field into its components i.e. #E_x , E-y, E_z#...
45. Calculating electric charge from graph (capacitor)

Apparently, we need to integrate the functions from 0 to the time when it is fully charged. However, I integrated in terms of t so the soultion (according to a graph programme) should be around 236 Vs but I don’t see how this could help me.
46. B What exactly is spin? Does the standard model work without spin?

I did some research online and found that "When certain elementary particles move through a magnetic field, they are deflected in a manner that suggests they have the properties of little magnets." To explain this phenomenon, physicists invented the concept of spin. So far so good. What I...
47. I Surface charge of neutral solids

Also referring to the post by @Kostik plus answers, I'm wondering about surface charges of neutral solids such as metals or carbon, for example. I only want to discuss large scale effects so that the solid can be treated as continuous. The atomic structure is averaged out. I also assume that...
48. Electric and magnetic fields of a moving charge

Part a) My solution: Big R basically becomes r, and the electric and magnetic field lines are doubled because of superposition principle. Am I right?
49. What is the charge for Hexaminotriphenylene?

I have seen the structures like X3 (HITP)2 (X = Cr, Mn, Fe, Co, Rh, Os, Ir). Can I replace X with Mg? Will it be stable?
50. Charge of 2 conducting spheres separated by a distance

First assuming only one sphere at a potential of 1500 V, the charge would be q = 4πεrV = 4π(8.85×10 −12C2/N · m)(0.150 m)(1500 V) = 2.50×10−8C. The potential from the sphere at a distance of 10.0 m would be V =(1500V)(0.150m)/(10.0m) =22.5V. I don't understand the reasoning of the...