Electric Definition and 1000 Threads

Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others.
The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field.
When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of positive charge from an arbitrarily chosen reference point to that point without any acceleration and is typically measured in volts.
Electricity is at the heart of many modern technologies, being used for:

Electric power where electric current is used to energise equipment;
Electronics which deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. The theory of electromagnetism was developed in the 19th century, and by the end of that century electricity was being put to industrial and residential use by electrical engineers. The rapid expansion in electrical technology at this time transformed industry and society, becoming a driving force for the Second Industrial Revolution. Electricity's extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society.

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  1. pixelsnpings

    Calculating temp rise caused by electric arc in an enclosed space

    Summary:: Given a known closed space/apparatus ( e.g. constant volume, pressure, density, current, temperature, voltage, spark gap distance - let me know if I missed something) how would I compute the change in gas temperature. Hello, Given a known closed space/apparatus ( e.g. constant...
  2. V

    Electric flux through ends of an imaginary cylinder

    When I look at this question, I can see two possible values of electric flux depending on how I take the normal area vector for either ends ##A \text{ and } A^{'}##. What is wrong with my logic below where I am ending up with two possible answers? The book mentions that only ##2E\Delta{S}## is...
  3. rudransh verma

    I What is Electric Flux and How is it Calculated?

    Gauss law relates between E at some point on guassian surface with the net charge enclosed by that surface. Using gauss law is like being able to tell what (ie charge)is inside a gift box by just looking at the wrapper(electric field). There are two types of problem. Sometimes we know the charge...
  4. jaketodd

    B Do contracting muscles emit electric fields?

    I bought an EMF meter that can discriminate to electric fields, and it is highly sensitive to the proximity of my body. What is it in the human body that emits electric fields? Is it muscle activity? Maybe many things in the body? Thanks.
  5. V

    Magnitude of electric field E on a concentric spherical shell

    The only explanation that I have seen in textbooks is that since the outer spherical shell is symmetrical relative to internal charged spherical shell so field every where on the outer shell is same in magnitude at every point on it. I can understand that electric field needs to be...
  6. Shreya

    Force on a dipole in a non uniform electric field

    I have figured out how the force is towards left in the first case. I think it is due to the larger force on - charge. Please help me out with the second and third case.
  7. Shreya

    Flux density and Divergence of Electric field

    I think Flux density is flux/Volume. Or is it flux/ Area Please be kind to help
  8. Shreya

    Need Help Understanding Electric Flux and Electric Flux Density

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  9. jaumzaum

    I What's the electric potential of the Earth?

    I was wondering, we constantly assume the reference of zero potential is the surface of the Earth. But if we consider the reference to be the infinity, what would be the electric potential of the Earth? As Faraday says, the Earth is charged with a -580 kC of negative charge. If we consider...
  10. M

    Expression for the magnitude of an electric field

    k(q_1-q_2)/(R^2+x^2)^3/2
  11. B

    Show that the given electric field is a plane wave

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  12. H

    B Distribution of energy in the electric field surrounding an electron

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  13. J

    Sketch the Electric Field at point "A" due to the two point charges

  14. Istiak

    The Electric Field and Potential Energy in a Spring System

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  15. Eliasm

    Magnitude of the electric field?

    Zzzz
  16. yucheng

    What's wrong? Electric potential of a point on a ring

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  17. anorlunda

    New Electric Airplane for Package Delivery

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  18. uni98

    Electric field of wire and cylinder at one point in space

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  19. J

    A Electric charge amplitude mode superconductivity

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  20. V

    How Do Charges Separate on the Second Ball in Electrostatic Induction?

    I used the concept of electrostatic induction, which would cause the charges in metal ball near the ebonite rod to have +ve charges on end next to rod and a -ve charge on the end touching the other ball. What confuses me is how charges separate on the second ball. The only way these balls can...
  21. A

    MHB Multiple choice question about electric fields and magnetic fields

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  22. meher4real

    Electric field between two parallel plates

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  23. eric11201120

    Expression for Electric Field Outside Sphere

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  24. Paul Colby

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  25. E

    Engineering Understanding the Relationship Between Voltage and Electric Field

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  26. Lucas123

    Engineering Solve Motor Coil Current at Startup & Full Speed

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  27. Xiao Xiao

    Engineering Electric Circuit Analysis of this First Order R-L Circuit

  28. Magnetons

    Electrons in Electric Fields: Examining Changes

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  29. S

    Electric fields of charged plates

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  30. S

    How does the strength of an electric field relate to its direction?

    I understand that negative charges create electric fields pointing inwards, and positive charges create electric fields pointing outwards, but what does this have to do with field stength? What is the relationship between field strength (flux?) and direction?
  31. J

    Monopole and Dipole Terms of Electric potential (V) on Half Disk

  32. H

    What is the maximum electric field magnitude between the cylinders?

    I used a couple ways to do this question, but I got neither correct. Can someone help, please? Thank you. 1. E= V/r = 700 / (60*10^-3) = 11667 (very far from the given answer) 2. E = (-kQ/r)⋅ dr = kQ/r^2 = kQ/ [( 1/20/ 10^-3)^2 - (1/80/10^-3)^2] (For this method, I stuck...
  33. Xiao Xiao

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  34. V

    Find electric field intensity/density with given potential difference

  35. H

    Is the Induced Electric Field Proportional to Radius in a Cylindrical Region?

    I used the equation below and the attachment to rationalize. https://www.physicsforums.com/attachments/282163
  36. A

    Moving electric field effect on dielectric/gas

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  37. jay_chay22

    Find electric field separating two charged masses suspended on strings

    Please help me on this question I have tried to do it many times but I end up getting the wrong answers. I have show my work what I have done.
  38. Hamiltonian

    Electric flux through a square lamina

    taking origin at the centre of the square. ##d\phi = \vec E.\vec{da}## $$d\phi = \frac {kqa}{(x^2 + y^2 + a^2)^{3/2}} da$$ $$\phi = \int_{-a/2}^{a/2}\int_{-a/2}^{a/2}\frac{kqa}{(x^2+y^2+a^2)^{3/2}}(dx)(dy)$$ on evaluating this double integral i get $$\phi = (q/\pi{\varepsilon}_0...
  39. E

    I Co-rotating electric potential for KN solution

    I am trying to work out the co-rotating electric potential ##\Phi = \xi^{\mu} A_{\mu}## for the KN solution. First it's necessary to prove that the hypersurfaces ##r = r_{\pm}## are Killing horizons ##\mathcal{N}_{\pm}## of a Killing field of the form ##\xi = k + \Omega_H m## for some Killing...
  40. RodolfoM

    Electric potential inside a hollow sphere with non-uniform charge

    I tried to find the charge distribution using the given potential but couldn't produce the correct result. Also, Gauss's Law doesn't help, as the electric flux is 0 but we don't have any symmetry. Can someone please shine a light on this? Thanks in advance..
  41. U

    Clarification on electric quadrupole moment definition

    I have encountered two (?) definitions of the electric quadrupole moment. They are: $$Q_{ij}=\frac{1}{2}\int \rho(\vec{x}')x'_i x'_j\,\mathrm{d}^3x'$$ and $$Q_{ij}=\int (3x'_i x'_j-\delta_{ij}x'^2)\rho(\vec{x}')\,\mathrm{d}^3x'$$ I am trying to study radiation arising from the electric...
  42. Xiao Xiao

    Electric Circuit Analysis, Nodal Analysis and finding Voltage.

    Summary:: The image shows two circuits, in the first one, using Nodal Analysis we find that V1=4.8V, but in the second circuit V1=10 because using KCL - 10+V1=0. I understand what happened in the first circuit, but I don't understand what happened in the second one, they look the same to me...
  43. Xiao Xiao

    Engineering Help in Electric Circuit Analysis -- One current source and a resistor network

    o9
  44. S

    Electric Field Intensity: Intersecting E-fields Explained

    This the photo of my textbook, Here In the derivation of Electric Field Intensity due to an infinitely long straight uniformly charged wire - In the figure 1(c).20 Vector E1 and vector E2 are electric fields at point P due to the two line elements as shown in the figure 1(c).20. But, in this...
  45. Mayan Fung

    Electric field acting on the source charge

    I am reading Griffith's textbook on EM. There is a problem asking to find the force acting on the northern hemisphere by the southern hemisphere of a uniformly charged sphere. The solution idea is to find the expression of the E field by Gauss's law and integrate the force over the northern...
  46. Mayhem

    Electrostatics: Coloumb's law and the Electric Field

    Hi. How does the charge ##q## relate to the charges ##q_1, q_2## (see equations). For example, if ##q_1## is an electron and ##q_2## is a proton, is ##q## just a product or sum or something else of the two? Also, in Columb's law, how would I conceptualize charges ##q_1, q_2## in a system of a...
  47. P

    Work Done on A Proton in an Electric Field

    W=-qEd =-(1.6*10^-19)(23)(0.75) = -2.76*10^-18 J However, the answer is 2.76*10^-18 J. Why is the word done positive and not negative? Since it's traveling in the same direction as the electric field, shouldn't it be negative work?
  48. Fisherman199

    Is There a New, More Efficient Electric Motor?

    Electric Motor Start-Up I have done little research into this so far but my "Law of Thermodynamics" alarm is blaring loud-and-clear. Has anyone here heard of this "new motor?" Has anyone tested one in the field?
  49. U

    Trying to understand electric and magnetic fields as 4-vectors

    I was trying to show that the field transformation equations do hold when considering electric and magnetic fields as 4-vectors. To start off, I obtained the temporal and spatial components of ##E^{\alpha}## and ##B^{\alpha}##. The expressions are obtained from the following equations...
  50. A

    Blown diffusior electric turbine wing....thing

    https://defense-update.com/20160303_vtol_x_plane.html you take the exhaust and pump it at the lip of the curve of a wing and try to aim it to maximize the coanda effect. it should look like a blown diffusior laid flat along the wing tucked in the square holes that the electric turbines are located.
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