What is Charge: Definition and 1000 Discussions

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. L

    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!
  2. eneacasucci

    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...
  3. E

    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...
  4. Tofuwu6

    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 =...
  5. C

    Semi-circular charged rods

    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...
  6. Count

    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?
  7. C

    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 /...
  8. L

    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?
  9. A

    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?
  10. S

    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...
  11. A

    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...
  12. R

    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...
  13. the_fater

    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...
  14. KnightTheConqueror

    B Confused about this force calulation in Resnick Halliday Krane Electrostatics

    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?
  15. Pouramat

    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?
  16. misbah alshaybani

    B Why is the test charge always positive?

    why test charge is always positive ?
  17. sarah123

    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?
  18. DanielGuh

    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...
  19. guyvsdcsniper

    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...
  20. K

    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?
  21. C

    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...
  22. Edy56

    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.
  23. B

    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?
  24. paulimerci

    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...
  25. paulimerci

    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...
  26. paulimerci

    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...
  27. T

    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
  28. ARoyC

    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
  29. W

    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?
  30. P

    B How did fundamental charge thinking develop?

    How did fundamental charge thinking develop?
  31. ananonanunes

    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...
  32. L

    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#...
  33. K

    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.
  34. DomDominate

    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...
  35. Philip Koeck

    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...
  36. milkism

    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?
  37. D

    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?
  38. J

    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...
  39. L

    Finding Charge Density on the Surface of a Slab

    Here's my attempt at a solution, but when I plug it in, it gives me a power ten error. I don't really understand what I'm doing wrong here. I think all my variables are in the correct units and it asks for my answer to be in μC/m2. Any help is much appreciated.
  40. F

    Magnitude of the Line Charge Density of a Power Line

    Okay so I am a little confused as to where I made a mistake. I couldn't figure out how to program Latex into this website but I attached a file with the work I did and an explanation of my thought process along the way.
  41. C

    Finding charge on a capacitor given potential difference across two points

    For this part(b) of this problem, The solution is However, I tried solving (b) like this: Since ##Q_{total} = 363 \times 10^{-6} C## then ##Q_1 = 181.5 \times 10^{-6} C ## since the equivalent upper capacitor is in series with the equivalent bottom capacitor so should store the same amount...
  42. C

    Ranking charge stored on three capacitors by a battery

    For this problem, The solution is, I have a few questions about parts of the solutions, - Part(b): (1) Why do they assume that the capacitors are initially uncharged? Do they even need to make that assumption because it seems clear to me that we are finding the charge stored by each...
  43. P

    I The electron as a smeared charge density

    Schrodinger’s original interpretation of the wavefunction was that it represented a smeared out charge density however this was replaced with Max Born’s probability interpretation. The issue was from what I understand that a charge density would repel and have self interactions as all the charge...
  44. Pushoam

    Charge upon a parallel plate capacitor

    a) if I take a Gaussian cylindrical surface whose circular area are present in the meat of the two plates of the capacitor, then the electric flux through this Gaussian surface is zero ( as the electric field inside the meatof the capacitor is zero and between the capacitors, electric field is...
  45. Pushoam

    I Conservation of charge in the Universe

    The charge of an isolated system is conserved. This implies the charge of the universe is constant. This implies that charge can neither be created nor destroyed. This implies that the net positive charge and the net negative charge of the universe are conserved. Is this right?
  46. C

    Calculating Linear Charge Density of a Cylinder

    For part a: I know that linear charge density is the amount of charge per unit length, and we are given the volume charge density. Since we are given the volume, we can obtain the length by multiplying the volume by the cross sectional area, so C/m^3 * m^2 = C/m. The cross sectional area of a...
  47. S

    Powder coating: way to add more positive charge?

    I am thinking of powder coating at home. I know the part to be coated is negatively charged because it is grounded. I assume the powder is positively charged by the gun. I wonder if there is a way to add more positive charge cheaply to an inexpensive gun like the one at harbor freight? I think...
  48. C

    Finding value of unknown charge

    For this problem, The solution is, However, why did they assume that the electric field produced by charge q is always pointing to the left at the origin? Many thanks!
  49. noowutah

    Find the electric field of a long line charge at a radial distance

    TL;DR Summary: Find the electric field of a long line charge at a radial distance where the potential is 24V higher than at a radial distance r_1=3m where E=4V/m. Answer: 29.5V/m. Never mind: I retract this question. The integral apparently is supposed to diverge! I apologize for not reading...
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