Electric charge Definition and 274 Threads

Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charge: positive and negative (commonly carried by protons and electrons respectively). Like charges repel each other and unlike charges attract each other. An object with an absence of net charge is referred to as neutral. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that do not require consideration of quantum effects.
Electric charge is a conserved property; the net charge of an isolated system, the amount of positive charge minus the amount of negative charge, cannot change. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms. If there are more electrons than protons in a piece of matter, it will have a negative charge, if there are fewer it will have a positive charge, and if there are equal numbers it will be neutral. Charge is quantized; it comes in integer multiples of individual small units called the elementary charge, e, about 1.602×10−19 coulombs, which is the smallest charge which can exist freely (particles called quarks have smaller charges, multiples of 1/3e, but they are only found in combination, and always combine to form particles with integer charge). The proton has a charge of +e, and the electron has a charge of −e.
Electric charges produce electric fields. A moving charge also produces a magnetic field. The interaction of electric charges with an electromagnetic field (combination of electric and magnetic fields) is the source of the electromagnetic (or Lorentz) force, which is one of the four fundamental forces in physics. The study of photon-mediated interactions among charged particles is called quantum electrodynamics.The SI derived unit of electric charge is the coulomb (C) named after French physicist Charles-Augustin de Coulomb. In electrical engineering it is also common to use the ampere-hour (Ah). In physics and chemistry it is common to use the elementary charge (e as a unit). Chemistry also uses the Faraday constant as the charge on a mole of electrons. The lowercase symbol q often denotes charge.

View More On Wikipedia.org
Recent contents Top users
  1. 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...
  2. LarryS

    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.
  3. Behrouz

    Exploring the Nature of Charge in Electrons and Protons

    Is it right to say that 'modern physics has no deep explanation of the nature of charge' in electrons and protons?
  4. 1

    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...
  5. 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...
  6. L

    Electric circuitry, confusion about the electric charge

    Homework Statement car's battery has voltage (E) 11,5 volts and internal resistance of 0,040 ohms. battery's charge is 20 amperehours (20 Ah) How many ignition attempts of the car can be made, when the charge can be allowed to fall to 15 amperehours. One attempt of at engine ignition...
  7. DuckAmuck

    Electric Charge Interacting with Magnetic Monopole

    Is there a general solution explicitly worked out for how a monopole and electic charge would interact? Of course the electro-static solution is that there is no interaction, but the electro-dynamic solution would not be so trivial, as moving charges/monopoles would induce magnetic/electic fields.
  8. 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...
  9. Fernando Valadares

    Electric flux density of oscillating electric charge

    Homework Statement The electric flux density in free space produced by an oscillating electric charge placed at the origin is given by \vec{D}=\hat{r}\frac{10^{-9}}{4\pi r^2}cos(wt-\beta r), \ \ where \ \beta=w \sqrt{\mu_0 \epsilon_0} Find the time-average charge that produces this electric...
  10. F

    International Change Electric Charge Day

    Hello. What would you think of the international scientific community calling to change all negatively charged particles to positive and vice versa? Do you think there's a circumstance where we should switch or should have switched? The only reason I brought this up is that it came up when...
  11. M

    Electric charge and force question

    Homework Statement q1 = 25 μC at (0,1) and q2 = 20 μC find a.) q3 if q1 is in the negative x direction Homework Equations E=kq1q2/r^2 The Attempt at a Solution I keep trying to add vectors to find q3 ie ( -(25 μC) + 20 μC) and get 5 μC the book answer says 20 μC
  12. Y

    Electric charge is distributed inside a nonconducting sphere

    Homework Statement Electric charge is uniformly distributed inside a nonconducting sphere of radius 0.30 m. The electric field at a point P, which is 0.50 m from the center of the sphere, is 15,000 N/C and is directed radially outward. At what distance from the center of the sphere does the...
  13. GuhaGubindam

    Which direction does a charged particle move in a magnetic field?

    I understand that a cathode ray will be attracted to one pole of a magnet, while being repelled away by the other. The cathode ray, being electrons and thus negatively charged, must definitely be attracted by the positive pole of the magnet, while being repelled by the negative pole of the...
  14. Monkey_Man08

    What is the unknown charge if the net electrostatic force on particle 1 is zero?

    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...
  15. V

    Has the Charge Quantization Problem Been Solved Without Magnetic Monopoles?

    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...
  16. LarryS

    Exploring the Relationship Between Electric Charge and Gauge Symmetry

    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.
  17. M

    Electron-Proton Pair: Exploring the Possibility in an 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?
  18. 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...
  19. T

    Electric Charge Applied on Two Wires of Electroscope?

    Homework Statement A large electroscope is made with "leaves" that are 78-cm-long wires with tiny 24-g spheres at the ends. When charged, nearly all the charge resides on the ends of the spheres. (See diagram attached) If the wires each make a 26° angle with the vertical, what total charge Q...
  20. C

    Wikipedia electric charge page confusion

    Why does Wikipedia's page on electrical charge have a picture of a positivity charged object with arrows going to a negatively charged object? Doesn’t electrons flow from a negatively charged object to a positively charged object? Or is the picture just showing conventional current? Thanks.
  21. 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...
  22. 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...
  23. 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 =...
  24. B

    Calculating Work Done per Unit Charge in an Electric Field

    Homework Statement A charged particle is moved from a great distance to a distance d from a point charge. At distance d, the electric field has a strength E and a potential V. Which of the following represents the work done per unit charge q? Homework Equations F = Eq; V = Ed, E = kq/r^2; U...
  25. B

    Electric charge and potential energy

    Homework Statement A particle with charge q experiences a force F when placed a distance d from a point charge. At a distance d, the electric field has a strength E and a potential V. Which of the following represents the potential energy of the charge? (A) Fd (B) Eqd (C) Vq (D) Ed Homework...
  26. Hardik Batra

    Electric field and electric charge inside the Earth?

    As we know, If you put charge on conductor then all the charge reside on the surface of the conductor and charge inside the conductor is zero and electric field is also zero. Earth is also a good conductor. So the charge resides on the Earth surface? Is there no charge inside the earth? And...
  27. lonely_nucleus

    Can hot objects become 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.
  28. J

    Calculating E due infinite line and point charge?

    Homework Statement Here is the problem I am stuck on. I have checked my process multiple times, but have come up with the same wrong result. I would like to find out where by error of thinking lies. "An infinitely long line charge of uniform linear charge density λ = -1.30 µC/m lies parallel...
  29. C

    Electric charge inside a uniformly distributed sphere

    1. The problem statement, all variables and given/known my book says inside of a uniformly distributed sphere is zero and it also says it is not it is increasing. I didnt understand any single thing it is like kidding me? Homework EquationsThe Attempt at a Solution
  30. I

    Electric charge on rubbed objects

    When two objects say glass, fur, plastic, ebonite rod etc are rubbed with each other then why is it that glass rod, wool, fur gain positive charge while ebonite rod, plastic rod gain negative charge? I know that it's because of transfer of electrons...but why does the transfer of electrons...
  31. N

    Electric charge flow in AC and DC

    Can I say that energy transmitted in DC by electrons flow like ants walking align and in AC by electron vibration like water wave ?
  32. D

    Electric Field Work on Moving Charge

    Homework Statement An electric field does 40 J of work on a charge moving from point A to point B in a straight line at a distance, d. If the charge moves through a different path from point C to point D at a distance of 2d, what is the work done on the charge? Homework Equations W=Fd The...
  33. K

    How does Earth maintain its electric charge balance?

    Earth has a charge of -1.6×10^-19C or about 7 moles of excess electrons on it's surface. This is compensated by an equal deficiency of electrons in the Earth's upper atmosphere. Earth is also an infinite source and sink of current. Now, when current flows into it, that means it loses...
  34. B

    Electrical neutrality in radioactive decay

    Although it was drummed into me that electrical neutrality is preserved, I am perplexed by the phenomenon of radioactive decay. How is electrical neutrality maintained when electrons (beta particles) and proton-neutron sets (alpha particles) are being spit out by some elements. These particles...
  35. abrogard

    Relative Magnetic Fields: What is Reality?

    According to page 61 'Einstein' by Andrew Robinson an electric charge at rest produces no magnetic field. But: For an observer moving East with uniform motion the charge will appear to be moving West uniformly and B, using a sensitive compass, will detect a magnetic field around the 'moving'...
  36. Y

    Three charges located on a straight line

    Homework Statement Three charges, Q1, Q2 and Q3 are located on a straight line. The charge Q3 is located 0.169 m to the right of Q2. The charges Q1 = 1.56 μC and Q2 = -3.03 μC are fixed at their positions, distance 0.268 m apart, and the charge Q3 = 3.18 μC could be moved along the line. For...
  37. N

    What is the electric charge of Higgs particle?

    What is the electric charge of Higgs particle?Then if it is charge particle why must we give that particle the charge? In GWS model we introduce a scalar field in the spinor representation of SU(2):(H^+,H^0) .Then why must we choose positive charge for H^+? Now,I think that Q=T^3+Y/2,and we...
  38. Islam Hassan

    Electric Charge vs Mass in Gauge Bosons

    Is there any significance to the fact that: The electromagnetic and strong interactions have gauge bosons with no electric charge that are massless; and The weak interaction has two massive gauge bosons which do have electric charge. If there is a significance to this 'observation' then where...
  39. B

    Electric Charge in Dogs - Science Explained

    Hi, I've got a question which I can't google, I' haven't found anything about this. My dog simply shock me. Yes, I know static electricity and stuff but I wonder why this happens only when he is excited about something? For example I tell him that we're going for a walk and when I touch him he...
  40. A

    Understanding Electric Charge: Is it Just Electrons?

    I was reading my physics books. And then a question came across my mind. Now here the the definition of coulomb. Electric charge measured in units of coulombs. It takes about 6*10^18 electrons. So the question is did the electric charge only consists of electrons.
  41. barryj

    Magnitude of electric charge on a glass rod

    Homework Statement I am a physics tutor. I want to show the relationship between electric charges and forces and gravitational forces. I am relating an example as follows. If we have a hollow metal sphere the size of the Earth with a charge of 1.63E15 C and a piece of tinfoil the surface with...
  42. T

    Current Research on the Origin of Electric Charge

    Hello! I am not sure if this is the correct place for this but here is a go. I'm currently applying to graduate schools and I know that I am interested in theoretical particle physics and condensed matter theory. In electricity and magnetism we were told that charge is an axiom and it's not...
  43. Y

    Oil Drop Electric Field Problem

    Homework Statement An oil drop is charged negatively. How much charge is on the drop if the Electric Field is 6,400 N/C at a distance of 1.2 m? Homework Equations E=k q/r^2 I don't know if I should be using that equation for this one. The Attempt at a Solution I tried to do E/(k x r^2) = q...
  44. A

    Electric charge in parallel plate capacitor with 2 parallel dielectrics

    Homework Statement My question is: If we have a parallel plate capacitor with 2 parallel dielectrics both taking A/2 of the complete surface, is the total electric charge equal to sum of the electrical charges in the first dielectric and the second dielectric, i.e is qtotal=q1+q2=σ1*A/2+σ2*A/2...
  45. 2

    Can an Earthed Conductor Become Charged by a Nearby Charged Object?

    Homework Statement I never quite understood the principles of earthing, but I think that the general idea is that if you have an object with excess charge (whether positive or negative), then connecting it to the Earth with a conductor will mean that either the excess electrons flow to the...
  46. Godparicle

    Can an electron exist at many places at the same time?

    If I am not wrong, the Michio says that an electron (not the parts of an electron) can be found in many places at the same time. Is that right? If that is the case, consider a gaussian surface enclosing the electron at many places at the same time, then the charge inside the surface will be...
  47. M

    How to Calculate the Magnitude and Angle of the Total Force of Three Charges?

    How do you calculate compute the the magnitude of the total force of three charges and also the angle it makes with the x-axis? Knowing the magnitude and also the 2d co ordinates of the charges. I have deliberately not given any specific values because this is not homework its a question from...
  48. R

    What Is the Charge of q if the Net Force on the 1.0 mC Charge Is Zero?

    Homework Statement In this diagram, the net force on the 1.0 mC charge is zero. What is the sign and magnitude of the unknown charge q? Please see attached photo. [/B]Homework Equations F = KQ1Q2/r^2[/B]The Attempt at a Solution I have approached this by first determining the force...
  49. aditya ver.2.0

    What actually an Electric Charge ?

    Since schooldays, we have been learning that electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. But what's actually a charge, energy or force or is it something else??
  50. K

    What is the Correct Electric Charge Force Diagram for a Single Charge?

    I drew a force diagram of one charge with gravity downward, electric force to the right, and tension at 20 degrees left of +y. I summed the forces in the x and y directions: Fy = Tsin20° - mg = 0 T = 0.1434 N Fx = kq^2 / r^2 - Tcos20° = 0 q = 6.29 x 10^-12 C The correct answer is...
Back
Top