Charge Definition and 1000 Threads

  1. Lilian Chan

    What is the net force on the -1nC charge in this Coulomb's Law problem?

    Homework Statement link: https://ibb.co/Xy9s6DR What is the magnitude of this force? Homework Equations Coulomb's Law Trig equations The Attempt at a Solution (.05 m)xcos(60)=0.025m (the distance between the two known charges) F(between the two known...
  2. A

    Variable induced surface charge density on a sphere

    Homework Statement Homework Equations While solving this problem at r >>a ,the corresponding potential due to the dipole is kpcosθ/r2(potential due a dipole) where k is the electrostatic constt. ...(1) If σ(θ) is the surface charge density induced due to external electric field. then the...
  3. A

    How does the dielectric affect the charge distribution on a charged sphere?

    Homework Statement [/B]Homework Equations [/B] ∫Dperpendiculards=qenclosed freecharge D=ε0E+P The Attempt at a Solution D1+D2=q/2πr2 at a distance r from the centre How to find D2 which is at the lower boundary e.g inside the dielectric??
  4. 1977ub

    B Relativistic Mass-Energy: Charge & Particles

    Does The Presence of Charge Add To Relativistic Mass-Energy, or does it take two particles attracting or repelling one another to generate charge-related mass-energy?
  5. Zack K

    Distance of a Point Charge: Solving for Initial Distance Using Relativity

    Homework Statement You make repeated measurements of the electric field ##\vec E## due to a distant charge, and you find it is constant in magnitude and direction. At time ##t=0## your partner moves the charge. The electric field doesn't change for a while, but at time ##t=24## ns you observe a...
  6. G

    Potential generated by a point charge in a isotropic medium

    Homework Statement When a point charge is positioned at the origin = 0 in an isotropic material, a separation of charge occurs around it, the Coulomb field of the point charge is screened, and the electrostatic potential takes the form \phi(r) = \frac{A}{r} \exp\left( -\frac{r}{\lambda}...
  7. CalcNerd

    I Measuring Charge & Angular Momentum in Black Holes

    It is stated that a Black hole has only mass, angular momentum and charge for properties, but since it is black ie no light escapes its event horizon and charge E/M is related (same speed) as light (photons), how can unbalanced charge be detected? And since many Black holes have electron...
  8. Raihan amin

    Induced surface charge distribution

    Two identical metalic spherical conductor of radii ##R## are at a distance ##d## apart.One of the conductor has charge ##Q## while the another one is neutral.What will be the induced charge on the other conductor ? If we put an image charge ##q## inside the neutral one. Then the potential at...
  9. iVenky

    Surface charge on a conductor due to a charged rod 'q'

    Homework Statement A charged rod of charge 'q' is at a distance 'd' from a perfect conductor as shown below. What's the total surface charge on the conductor? 2. Homework Equations I tried to solve this without equations. The Attempt at a Solution [/B] Basically, as long as there is E field...
  10. M

    What Causes Discrepancies in Calculating Induced Charge Ratios?

    Dear colleagues I have this problem which I don't understand from where they got the solution I tried to solve it with slot of methods with the same answer which not the stated answer. A point charge (q) is located a distance (b) from a grounded conducting sphere with radius (a) show that the...
  11. fluidistic

    I Charge carrier density: Hall experiment vs Fermi-Dirac statistics

    Many times, the charge carrier density of a material is determined from a Hall effect experiment, from ##R_H=1/(ne)## (SI units). Where ##R_H## is determined from a measured voltage and other controllable parameters. As far as I know, this simple formula comes from the obsolete Drude's model...
  12. A

    Need a machine to impart measurable charge (Coulombs) at will

    Hi there, Does anyone know of a machine/equipment/technology, etc. that allows a person to give charges (Coulombs) to conductors in a measurable way? I've rubbed a ton of plastic rods with fur but that's not too measurable. The Van De Graaff is overkill or it if I try to connect alligator clips...
  13. M

    A Charge of the Vacuum in QED: Meaning & Implications

    Hello! When calculating the Hamiltonian operator in QED, in terms of creation and annihilation operators, we obtain an infinite term, which is considered irrelevant for most part (beside some renormalization problems) because we usually care about the difference in energies, so that would be...
  14. V

    Magnetic field at a point due to a line of charge

    Homework Statement A wire carrying a current I in the positive x direction is located along the x axis. The wire is of finite length and is located between x = -L and x = L. Find the magnetic field at a field point located a distance a away from the wire. Homework Equations Biot-Savart law...
  15. T

    How Do You Calculate Charge Density in a Uniform Sphere?

    Homework Statement A charge Q is uniformly distributed throughout a nonconducting sphere of radius R. Write the expression of the charge density in the sphere? Homework Equations Charge density ρ=dQ/dV Gauss's Law ∫EdA = E(4ϖr^2) The Attempt at a Solution If Q is uniform then ρ=Q/dV and the...
  16. M

    Spin of a nucleus within an external magnetic field.

    When a nucleus is placed inside an external magnetic field, it aligns itself parallel to the field, as that is the most stable position for it to be in. In more technical terms: it acquires an alpha spin. When you shine radio waves at this nucleus, it absorbs energy and flips over anti-parallel...
  17. S

    How spacecrafts discharge static electric charge

    I was wondering how spacecraft s discharge when encountering van allen belts (for example the juno spacecraft around jupiter) since obviously there is no earthing and is it possible to remove excess charge to power something on the craft?
  18. J

    Force on a stationary test charge from a moving charge

    Given a test charge, let's say on the vertical y axis. Another charge vertically below it moves past at a significant speed compared to c. From the Lorentz transformations (in most E&M books) the electric field and thus the force on the test charge will be greater than would be the static...
  19. D

    Bound surface charge on a linear dielectric half-cylinder

    Homework Statement Problem statement in attached photo. This is an ungraded assigned problem which I am using to study for an exam, so I don't need the whole solution just help with a couple of points I am confused about. One: Part d) is really important to how I will answer part b). If we can...
  20. sneakycooky

    Find the charge q(t) for an LC circuit

    Homework Statement An LC circuit consists of an 82 mH inductor and a 17 microfarad capacitor that initially carries a 180 microC charge. The switch is open for t < 0 and is then closed at t = 0. a. Find the frequency of the resulting oscillations. b. At t = 1 ms, find the charge on the...
  21. B

    Question on the work done while charging up a capacitor.

    So the work done when charging up a capacitor is ##dW=VdQ## However, when we add a charge ##dQ## to the capacitor, ##V## also changes accordingly, so I was wondering why the work done wasn't written as ##dW=VdQ+QdV## (one that also takes into account t he change in ##V##). Thanks in advance.
  22. Aishikdesto

    Nature of charge at the junction of a composite wire

    Homework Statement Please help me answer thew question in the image.[/B] Homework Equations Current Density J=conductivity X Electric field[/B] The Attempt at a Solution As the current density depends on the conductivity of the material through which the electrons constitutuing it are...
  23. Raihan amin

    Contradiction in a charge redistribution problem

    Homework Statement There are two metallic spheres, of same kind ,separeted from one another .One of them has charge 6 C wheras the another one is neutral.They are brought in contact for a long time.Then they are separeted again.Now what is the charges of the spheres?Homework Equations ...
  24. SebastianRM

    What happens to the Electrical Potential the closer we are to a point charge?

    So I have been wondering: The potential for a point charge at the origin, is described as: (Using the reference point at infinity): V=1/(4πε) * q/r My question is, what happens to this Potential the closer we are to the point charge, and so the closer we would get, the Potential seems to go...
  25. CDL

    Einstein Velocity Addition for a Moving Charge in a Wire

    Homework Statement I am reading through Griffiths' Electrodynamics, and I have come to the scenario in the Relativity chapter where in an inertial reference frame ##S##, we have a wire, with positive charges (linear density ##\lambda##) moving to the right at speed ##v##, and negative charges...
  26. N

    Can NH2 with no formal charge on it be protonated?

    So I have this question that asks which is the strongest base. I have one structure with a benzene ring with an NH2 group on one side and a methoxy group on another side. Automatically I knew that the NH2 group would be what is protonated in the situation that this structure acts as a base and...
  27. archaic

    Force of one distribution of charge on another

    Homework Statement I need help on solving this exercise : We have a ring of radius = ##a## uniformly charged (total charge = ##Q##) and on its axis a segment ##OA## (length = ##a## also) of uniformly distributed positive electric charges with the charge density ##\lambda'## and of total charge...
  28. K

    Path of a deflected charge? Solvable ODE's?

    Homework Statement Suppose a particle of mass m and charge q is moving with velocity v(t) to the right in the second quadrant of a coordinate system C and whose position is described by the vector r(t) pointing from the origin to the particle's location in C. A charge with magnitude Q is fixed...
  29. YMMMA

    What would happen to the charge and capacitance?

    Homework Statement In the attached file.. The question asks about the charge and capacitance after being separated by twice the original separation. I also need to know if it is kept connected to the battery( spearted to twice the distance,too) , what would happen to both the charge and...
  30. T

    Electromagnetic Radiation Emitted By An Accelerating Charge

    Suppose a point charge is slowly oscillating simple harmonically. Does it emit an electromagnet wave and if not why not ? How does its field change with time. Does anyone know of a good animation ? Thanks.
  31. HotFurnace

    Calculating Velocity Change in a Moving Charge-Magnet Interaction

    Homework Statement A magnet is moving with constant velocity vector ##\vec V##. A charged particle fly through it. At first, the objects are place very far from each other, and the charged particle velocity vector is ##\vec V0##, after the charged particle cross over and fly away from the...
  32. DJ_Juggernaut

    B Moving Charge in a Magnetic field Problem

    Hi all. I am alluding to the Moving Charge in a Magnetic field problem by quoting an MIT lecture below. Scott Huges – Lecture http://web.mit.edu/sahughes/www/8.022/lec10.pdf Suppose we now examine this situation from the point of view of the charge (the “charge frame”). From the charge’s point...
  33. E

    Formula to calculate the charge in a sphere

    1. The problem is: Which charge will a sphere have if it has a diameter of 0.26 meters and produces an electric field of 1030 N/C in the surface? 2. Gauss Law3. I need the charge of the sphere but i couldn´t find any formula to calculate the charge given the distance (r) and electric field (E)
  34. A

    Finding Charge & Tension of a Suspended Cork Ball

    Homework Statement A charged cork ball is suspended on a light string in the presence of a uniform electric field. E=(3×10^5 N/C)i+(5×10^5 N/C)j. The ball is in equilibrium in the field. Find the charge on the ball. The acceleration due to gravity is 9.8 m/s2 . The mass of the ball is 0.7g. The...
  35. F

    How does a low charge on an A/C cause the subcooling to be low

    I know that having both high superheat and low subcooling on an Air-Conditioner (A/C) is a strong indication that an air-conditioner does not have enough refrigerant. When the charge on an A/C is low, there is less refrigerant that enters the evaporator. When there is a lower amount of...
  36. P

    Electric potential energy between charge and moving magnet

    The setup for one magnet Introduce a magnet: Inertial Frame 1 (or lab frame) A frame where a magnet is seen to move with uniform velocity v and carries a uniform polarization P while a point charge Q is seen to be stationary at time t=0. Inertial Frame 2 (or material frame) A frame where a...
  37. L

    Potential due to Uniform Charge Distribution (3d)

    Homework Statement Homework Equations dV= integral(kdQ/dR) The Attempt at a Solution So, I'm familiar with these type of problems but in 2D (like a line of uniform charge). When the y,z component is added, I'm kinda lost. i know dQ = p*dV= p*dx*dy*dz. (atleast i think it is). also the dR =...
  38. E

    How to Determine Electric Flow Through a Square Surface Due to a Nearby Charge?

    Homework Statement determine the electric flow through a square surface of side 2l due to a load + Q located at a perpendicular distance l from the center of the plane I really don't know how to answer this question .i need help guys Thanks Homework EquationsThe Attempt at a Solution I ended...
  39. S

    B What really is the charge of the electron?

    In my study of Quantum physics i have arrived at the natural shielding caused by photon to electron/anti-electron pair fluctuations.The shielding reduces as you get closer the electron which naturally leads me to the question.What actually is the charge on an electron?
  40. A

    Finite dual disk capacitor: estimating charge distribution

    Homework Statement Working through Purcell (among others) as fun applied math/math modeling refresher. But, I have struggled all week in establishing from first principles that the potential/field/distribution for a configuration of two capacitive disks of radius 1 and separation s along the...
  41. L

    Derivation of the Potential Energy of an Electric Charge System

    Hi, I learned about how PE = U=kq1q2/r is the electrical potential energy for the system. It is found by taking the integral of electrical force and dr from infinity to the point of location we are interested in. So that is the intregral(F*dr) from r=inf to r=ro. My question is that do I...
  42. cookiemnstr510510

    Electric field from spherically symmetric charge distributio

    Homework Statement A spherically symmetric charge distribution produces the electric field E=(200/r)r(hat)N/C, where r is in meters. a) what is the electric field strength at 10cm? b)what is the electric flux through a 20cm diameter spherical surface that is concentric with the charge...
  43. isukatphysics69

    A plate carries a charge of -5.2 μC

    Homework Statement A plate carries a charge of -5.2 μC, while a rod carries a charge of +1.8 μC. How many electrons must be transferred from the plate to the rod so that both objects have the same charge? Homework Equations N/A The Attempt at a Solution So I am imagining a plate and a rod...
  44. B

    Divergence of the E field at a theoretical Point Charge

    I've been thinking about this problem and would like some clarification regarding the value of the divergence at a theoretical point charge. My logic so far: Because the integral over all space(in spherical coordinates) around the point charge is finite(4pi), then the divergence at r=0 must be...
  45. isukatphysics69

    Determine the net charge of sphere C

    Homework Statement Consider three identical metal spheres: Sphere A carries a charge of -9q, Sphere B carries a charge of +3q, and Sphere C is neutral. Spheres A and B are touched together and then separated. Next, Sphere C is touched to Sphere A and then separated from it. Finally, Sphere C...
  46. Abhimessi10

    Charge distribution on concentric spheres

    Homework Statement Two thin conducting spherical shells have radii R1 and R2.Outer shell is charged to q and inner shell earthed.Find charge appearing on both the shells. Homework Equations The Attempt at a Solution Isnt the charge on inner shell 0 and charge on outer shell remains Q as it...
  47. Faizan Samad

    Finding the equipotential surfaces of a finite line of charge

    Homework Statement Consider a line of charge stretching along the z-axis from -L to +L. Find the potential everywhere. What are the surfaces of constant potential. (The next question answers the previous question and says its a prolate ellipsoid. Homework Equations I will upload an image of...
  48. Abhimessi10

    Charge entering into the field between capacitor plates

    Homework Statement A negative charge of mass m enters into the field between two deflecting parallel plates with length 'l' separated by distance 'd' with a velocity 'v'.Assuming electric field to be uniform,find the maximum charge so that it will not hit a plate Homework Equations Kinematic...
  49. cookiemnstr510510

    Electric field of ring of charge/washer of charge/disk of charge

    Homework Statement Homework Equations charge density equations, electric field equations, The Attempt at a Solution My attempts are attached. The attachment labeled A, is part A. Part B took a lot of paper so there are two attachments labeled B1 and B2. It is really B and C that I am...
  50. isukatphysics69

    How to Rank Charge Density of Conductive Spheres?

    Homework Statement Sphere 1 has net positive charge Sphere 2 has net negative charge Sphere 3 has net positive charge The ranking of net charge magnitudes are SPHERE 3 > SPHERE 2 > SPHERE 1 All spheres are conductors Sphere 2 is moved away from Sphere 1 and toward Sphere 3 so that 2 and 3...
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