Read about electric charge | 39 Discussions | Page 1

  1. F

    Reducing the charge Q on an isolated charged conducting sphere to Q/8

    It seems to me that one can obtain the required result by using just one neutral sphere and one ground wire. Let A be the charged sphere and B be the neutral one. Initially ##Q_A=Q## and ##Q_B=0##. put A and B in contact. As a result ##Q_A=Q/2## and ##Q_B=Q/2##. ground B, so that ##Q_B=0##...
  2. C

    I Electrical potential of a thin wire in an E field

    Assume that an infinite metallic plate A lies in the xy-plane, and another infinite metallic plate B is parallel to A and at height z = h. The potential of plate A is 0, and the potential of plate B is constant and equal to V. So, there is a uniform electrostatic field E between plates A and B...
  3. T

    Capacitance and induced charge of a spherical Capacitor + dielectric

    I) For the first part I used: ##V = - \int E ds = \int_a^c \frac{1}{4\pi\epsilon_0} Q /r^2 dr+ \int_c^{c+d} \frac{1}{k} \frac{1}{4\pi\epsilon_0} Q /r^2 dr + \int_{c+d}^b \frac{1}{4\pi\epsilon_0} Q /r^2 dr ## And by using ##C = Q/V## We get an answer which is somehow large for writing here...
  4. Mutatis

    Find the electric field at an arbitrary point

    Homework Statement A distribution of charge with spherical symmetry has volumetric density given by: $$ \rho(r) = \rho_0 e^{ \frac {-r} {a} }, \left( 0 \leq r < \infty \right); $$ where ##\rho_0## and ##a## is constant. a) Find the total charge b) Find ##\vec E## in an arbitrary point...
  5. C

    I Floating potential of a conductor in an electrical field

    I'm interested in the following general question: Assume x,y,z is an axes system, and that the y-z plane is occupied by a conductive plate at a known potential V with respect to the earth. Now, a conductive material M of neutral global electrical charge is placed at some distance of the plate...
  6. C

    I Electric field created by a charge seen through an infinite plate (dielectric vs. conducting)

    Having come experimentally to an interesting electrostatic effect, I have returned, aged 47, to my old books in physics. It turns out that my books delight in using Gauss theorem etc. in rather ideal geometrical surface charge distribution, but never gave me the tools to answer to this simple...
  7. J

    Drawing electric field lines

    Homework Statement In the diagram, two small objects, each with a charge of -4.0nC, are held together by a 0.020 m length of insulating string. The objects are initially at rest on a horizontal, non conducting frictionless table & the effects of gravity on each other are negligible. (b)...
  8. B

    Electric field inside/outside (uniformly charged sphere)

    A sphere of radius a carries a total charge q which is uniformly distributed over the volume of the sphere. I'm trying to find the electric field distribution both inside and outside the sphere using Gauss Law. We know that on the closed gaussian surface with spherically symmetric charge...
  9. M

    I Elementary Charge

    My textbook states: "The magnitude of charge of the electron or proton is a natural unit of charge." and then has an explanation that follows. It states, "...The charge on any macroscopic body is always either zero or an integer multiple (negative or positive) of the electron charge." Here is...
  10. Manolisjam

    Non-conductve sphere with cavity -- find Electric field

    I have a non conducting sphere with a charge ρ=A/r per uni vollume A is constant. suppose there is a cavity in the centre and within a particle of charge q. i want to find the E inside the sphere in respect with r. Homework Equations The Attempt at a Solution for radius equal of the cavity i...
  11. M

    B Dimension of the electric charge in CGS and in SI?

    The Bohr magneton is (see e.g. Wikipedia) in SI units: $$\mu_B=\frac{e\hbar}{2m_e}$$ and in CGS units: $$\mu_B=\frac{e\hbar}{2m_ec}$$ So the dimension of the electric charge in SI, ##[q_{SI}]##, is related to the dimension of the electric charge in CGS, ##[q_{CGS}]##, by...
  12. Z

    Coulomb's force - magnitude of the electric force

    Homework Statement Show that the magnitude of the electric force on each ball is given by Fe = mgtanθ/ (cosα+ sinαtanθ) where θ = arcsin(x2/L) α = arcsin((y2-y1)/r) r = √((x2-x1)^2+(y2-y1)^2) This is a question from my coulomb's law lab, where 2 styrofoam balls where charged, one was hung on a...
  13. T

    Did i calculate the V/A/R of a plasma arc properly?

    Hello there! So i am currently sitting in my EME class and have nothing to do, so i decided to try spit-balling the V/A/R of the plasma arc my Tesla Lighter produces. note that i did not physically take it apart, and my goal was just to get a rough estimate for the arc itself or at least get a...
  14. F

    Question about electrical potential energy

    Homework Statement Two charged plate hold a charge of 3 coulombs with the upper plate being positively charged and the lower plate being negatively charged. They have a pd of 6 volts. There is a spacing of 20 cm between them. A positive charge q with a charge 0.4 coulomb is located at midpoint...
  15. UseAsDirected

    B Why are two cellophane tapes attracted when ripped apart?

    Hello, I put two strips of cellophane tape adjacent to each other adhered onto a table. When I pull them both apart, they repel each other, both insulators ripped electrons from the wood. When I stack two strips of tape on top of each other on a table, rip the combined bundle off the table...
  16. dumbdumNotSmart

    Electric Field in a cavity of a charged sphere

    NOTE: Other threads suggest solving it with Gauss' Law. I'd like to see an approach through direct integration, no full followthrough necessary.. 1. Homework Statement Consider a sphere with a uniform distribution of charge ρ (ro). Inside the sphere is a cavity (spherical). Calculate the...
  17. referframe

    I How are protons, photons and quarks related electrically?

    When protons, due to their electric charge, interact with photons are the quarks somehow also involved in this same electric interaction? After all, the quarks do have fractional electric charges. Thanks in advance.
  18. Behrouz

    I Electric charge

    Is it right to say that 'modern physics has no deep explanation of the nature of charge' in electrons and protons?
  19. 1

    B Discharging capasitors and it's general electrical propertie

    It's just that i've never properly sorted this confusion of mind, so i would like to sort it out so it 2 different capacitors are in series with a resistor: (let's say 0.15F, 0.45F, 150M ohm) 1. both current and voltage drops exponentially 2. capacitance on capacitors remain same over time? 2...
  20. 1

    Why does the point experience NEGATIVE field strength?

    Hi, i'm looking for an explanation to this answer of a past paper that i'm doing, it's from OCR (A level) G485, question 1 b ii) the question on top, and answer on bottom i don't understand why would the point experience a negative electric field strength when it's getting closer to a...
  21. Futurestar33

    Electric engine for car vs Electric Engine for Drone

    Hello, I am trying to find out if there are any differences between how the Electric engine for car works vs how an Electric Engine for Drone works. I am sure the both consist of an Ignition coil, stator and rotor. However I have not been able to find the any schematics for a drones electric...
  22. Monkey_Man08

    Net Electrostatic Force

    1. The problem statement: In the figure four particles form a square with edge length a = 2.44 × 10-2 m. The charges are q1 = q4 = 1.06 × 10-15 C and q2 = q3 = q. What is q if the net electrostatic force on particle 1 is zero? All variables and given/known data: The given variable are in the...
  23. V

    Charge quantization problem solved?

    I am no mathematician, not even an expert in Gauge Theories, but I came across this article http://arxiv.org/abs/1409.6716 (published here http://www.sciencedirect.com/science/article/pii/S0393044015002284) when I was looking for some "condensed-matter-type-monopoles", and the author claims...
  24. referframe

    Property of Electric Charge

    Does the property of electric charge of an elementary or composite particle exist only within the context of gauge symmetry - of the complex phase of the wave function, i.e. does gauge symmetry define electric charge? Thanks in advance.
  25. M

    Alternative Universe

    Imagine a universe where electrons and protons have positive and negative electric charges, respectively. Could an atom consisting of one electron and one proton exist in this universe?
  26. P

    Charge on q from other charges given net force is zero

    Homework Statement Consider the figure below, we need to find the charge on Q_0, both charges Q are negative. It is given that the net charge on Q_A is zero. The figure of the problem is attached. The Attempt at a Solution I understand how to get the solution except for one part. I'm just...
  27. S

    Can charge be held in a vacuum?

    It's my understanding that matter holds charge on earth from the insulation of the atmosphere, since the atmosphere is a bad conductor and essentially blocks current due to the gaseous molecules' atomic structure and their covalent bonds. Does this mean it's impossible for matter to hold charge...
  28. P

    Figuring out the magnitude of electric repulsion

    Homework Statement [/B] In a certain organic molecule, the nuclei of 2 carbon atoms are separated by a distance of .20nm, What is the magnitude of the electric repulsion between them? Now, I know the distance between them, but it has to be converted into meters: .20nm = .20 X 10 ^-9m And...
  29. I

    Electric field using dielectric constant

    Homework Statement What is the magnitude of the electric field due to a 6.0 x 10-9 C charge at a point located 0.025m from the charge? The charge and the point in question are located underwater (κ(water) = 80). Homework Equations I know that E = magnitude of electric field = kq/r2, where k =...
  30. lonely_nucleus

    Are hot objects charged?

    Because a hot object like a hot metal has a lot of heat flowing through them are they charged? What are some ways to charge objects.
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