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. C

    Different types of electric motors

    I have to write a report about one of three motors AC type Motors, DC type Motors, Stepper Motors. I am wanting to now if anyone has any insight into which one I should talk about, which one has the most information and would be easiest to write a report on. Thanks
  2. B

    I Searches for electric dipole moments (EDM) in atoms

    Hello! I read some papers about searching for induced atomic EDM. Finding such an EDM would imply a violation of the P and T-invariance (and hence CP). The way the derivation works (very roughly) is by assuming you have a PT-odd interaction in the hamiltonian (coming from a possible nuclear EDM...
  3. greg_rack

    Final electric potential difference in a circuit with two capacitors

    So, each capacitor must have a different potential difference, given by its capacity and charge... this would cause charge and current accordingly to flow in the circuit. But how do I determine the final potential difference, which would of course be the same for both of them? I have tried...
  4. E

    Engineering Electric Power Systems book recommendation

    Summary:: Electric Power Systems book recommendation Hi everyone, I finished my Electrical Engineering degree 15 years ago and wanted to refresh/review/update my knowledge on Electrical Power Systems. I'm looking for a book recommendation that has: components of a power system, control of...
  5. Vossi

    Electric Circuit Differential equation help

    I'm confused at the part how 4Vc and 48 cos(60t) are deduced, that's all.
  6. P

    Electrostatic - electric potential due to a point charge

    Could somebody check my solution? I want to know is it correct.
  7. P

    Electrostatics: Calculate the Electric Field near a Charged Ring

    I have the problem with my solution. I don't know it is correct. Could somebody check it?
  8. greg_rack

    Electric potential difference at the ends of a resistor

    So, having two parallel resistor ##R_{1}## and ##R_{2}## , the current flowing through the equivalent one will be ##I_{eq}=I_{1}+I_{2}##. Now, it comes the point I'm not totally getting: why is ##V_{eq}=V_{1}=V_{2}##? These V's are the difference of potential measured between which points...
  9. huszarerik

    Electric field lines between a point-charge and a conducting sheet

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  10. J

    I Is the electric field of an atom a superposition or mean of electron positions?

    We usually think about atomic orbital as wave(function), but it was created from e.g. electron and proton approaching ~10^-10m (or much more for Rydberg atoms), and electron has associated electric field. This wavefunction also describes probability distribution for finding electron (confirmed...
  11. yyfeng

    Simple Electric Field due to a Charged Disk

    My attempt at a solution is shown in attached file "work for #10.png". I used Desmos Scientific online calculator to obtain my final answer.
  12. greg_rack

    Clarifications about electric potential and potential difference

    Specifically, I haven't really got all the "methods" through which you could calculate or derive the electric potential and in some situations, I cannot understand how and when to apply this concept. Is it something caused by any charge, or must there be an interaction between the two to...
  13. E

    The electric field inside a hole inside a conductor is still 0?

    This is not a homework question but something that bugs me a bit. My professor has stated that the electric field inside a conductor is 0. This I understand. However, he has also said that even if the conductor has some hole in it, the electric field inside this hole is also 0 Now, two...
  14. rude man

    Introduction to Electric Vector Potential and Its Applications

    Continue reading...
  15. willDavidson

    Electric field of a point charge

    I am trying to understand what a point charge is. Is it just an electron? Or is it just an idea?
  16. willDavidson

    Electric field in a second dielectric given a 2 dielectric system

    I tried approaching this by finding the tangential and normal electric fields. Is this the correct approach? I've attached a drawing of the surface provided. ##\oint_S E \cdot dl=0## ##E_{tan1}\Delta x-E_{tan2}\Delta x=0## We know that ##E_{tan1}=E_{tan2} Next, we can find the normal...
  17. Athenian

    Finding the Monopole and Multipole Moments of the Electric Potential

    My first attempt revolved mostly around the solution method shown in this "site" or PowerPoint: http://physics.gmu.edu/~joe/PHYS685/Topic4.pdf . However, after studying the content and writing down my answer for the monopole moment as equal to ##\sqrt{\frac{1}{4 \pi}} \rho##, I found out the...
  18. P

    Position for maximum electric field between two wires

    For the first part, since $$ E(r) \propto \frac{1}{r} \hat{r}$$ by the principle of superposition the maximal electric field should be halfway in between the two wires. Then I'm not sure how to go about the second part of the question. I understand that the total potential due to the two wires...
  19. M

    Find the electric field intensity from an infinite line charge

    what I've done so far? -i've determined the vector between the point (4, 0, 0) and the point P. (4, 6, 8) - (4, 0, 0) (0, 6, 8) -The norm of this vector is the radial distance of the line to point P (the value of “ρ” in the formula) √(0^2 + 6^2 + 8^2) = 10 -> ρ = 10 -and its unit vector is...
  20. wcjy

    Electric field problem using Gauss' law: Point charge moving near a line charge

    F = qE ma = (2*10^-6) * (λ / (2pi*r*ε0) ) ma = (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) => I am not certain what to put for r ( But I sub in 4 because dist is 4) a = ( (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) )/ 0.1 a = 0.35950 v^2 = U^2 + 2 a s v = 0 u^2 = -2 a s => Can't sqrt negative so...
  21. C

    Help finding the equilibrium position of an electric field

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  22. E

    Net electric force of multiple charged particles in 3-d space

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  23. zb23

    Electric Field Divergence of Monochromatic Plane Wave: Why is it Zero?

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  24. F

    Efficiency of charging new and old Li-ion batteries in electric cars

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  25. Sj4600

    How Do Electron and Proton Accelerations Compare Between Charged Plates?

    Ve=0m/s Vp= 0m/s Qe/Qp= 1.60E-19 Me=9.11E-31 Mp-1.67E-27 Ive pretty much gathered all of the equations I think I need to solve the problem. I just am stuck. The last step I realize that the forces would be equal to each other so I have mp x ap = me x ae but then when I try to solve for the...
  26. bln1230

    Help me find the electric field vector

    I have these equations in my book, but I don't know how I can use them in this problem Electric field of a plane has surface electric density σ: E = σ/2εε₀ Ostrogradski - Gauss theorem: Φ₀ = integral DdS Can someone help me :((
  27. B

    Electric Potential inside an insulating sphere

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  28. J

    Finding equations for electric field lines

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  29. P

    What causes an electric force in one situation but not in another?

    Hi, I'm dealing with a more or less trivial question. Let's have a look on two situations. Consider a (negative) charged metal plate. If the plate is infinit in size it will produce a perfekt homogeneous electric field. If we now place a second plate parallel to the first one the electric...
  30. archaic

    Maximum electric field at the surface of a Van de Graaff generator

    I know that the potential of the sphere at its surface is ##V(a)=kQ/a##, and the electric field generated by it is ##E(a)=kQ/a^2##, which gives me ##V(a)=aE(a)##. When the electric field at the surface is as in the question, we have...
  31. madafo3435

    Electric field due to a flat hollow disk

    I would like if my procedure is correct ... Due to the symmetry of the problem, I only worry about the vertical coordinate of the field, so I will work with the magnitude of the field, and I will treat the problem in polar coordinates. ##E= \int_{R_1} ^ {R_2} \int_{0} ^ {\pi} \frac {\sigma...
  32. G

    Contradiction in the formation of an electric dipole

    Solution as stated in the problem description.
  33. joey13

    Could electricity power a rocket? Feedback appreciated!

    Hi! I'm a high school physics student. I really, really love physics, especially rocket science, and I had an idea about a rocket design, but I don't know how feasible it is. I was hoping you guys could give me some feedback. So I was learning about electricity, and as far as I know, electric...
  34. J

    AC Electric Field vs DC Electric Field?

    I have an object that will be under DC excitation in operation but will be qualified using 60 Hz AC. Because of this, I am interested in 2 simulations. 1) I would like to simulate E-field intensity representing a 60 Hz excitation. Do I need to do a transient simulation to truly get this value...
  35. cwill53

    Electric Field at the end of a Half-Infinite Cylinder

    The approach used in the book uses polar coordinates. I was wondering if my approach would still be correct. I set up the problem such that the midpoint of one face of the cylinder is at the origin while the midpoint of the other end's face is at the point (##l##,0). The surface area of the...
  36. bryanso

    I Understanding Feynman's Relativistic Electric Field Equation

    Feynman's Lectures, vol. 1 Ch. 28, Eq. 28.3 is ##r'## is the distance to the apparent position of the charge. Feynman wrote, "Of the terms appearing in (28.3), the first one evidently goes inversely as the square of the distance, and the second is only a correction for delay, so it is easy...
  37. R

    Electric Field Between two Parallel Conducting Plates of Equal Charge

    Attached is the subsection of the book I am referring to. The previous section states that the electric field magnitude at any point set up by a charged nonconducting infinite sheet (with uniform charge distribution) is ##E = \frac{\sigma}{2\epsilon_0}##. Then we move onto the attached...
  38. agnimusayoti

    Electric field a distance z from the center of a spherical surface

    Well, I really don't understand what is the use of the hint. I try to solve this problem with Coulomb's Law and try to do in spherical coordinates and got very messy infinitesimal field due to the charge of infinitesimal surface element of the sphere. Here what I got: $$\vec{r}=\vec{r_P} +...
  39. R

    Potential Energy of an Electric Dipole in a Uniform Field

    I have a lot of questions about this single concept. You don't have to answer the questions in the order that I ask, if it is convenient to answer them in a different order. 1. When the dipole moment ##\vec{p}## is in the same direction as the electric field (uniform) it has the least potential...
  40. DarkMattrHole

    B How does the electric field of an electron compare to its probability wave?

    A single electron sitting in a void has an electric field that spreads out evenly in all directions as far as there is open empty space to allow it, is this roughly a correct statement? Let's say we now introduce a singe proton into the void, 100 miles from the electron - it will also have an...
  41. S

    How to calculate the induced charge in an electric field

    Maybe I should use this?
  42. S

    Physics Bachelors in physics with a minor in electric and computer engineering

    I am considering getting a physics bachelors with a minor in electric and computer engineering. I want to study computers and the hardware behind them, but also study the physics aspects of them. I also am considering going to graduate school to get a masters or PhD and doing research into...
  43. Tony Hau

    Why is the Electric Field of a Polarized Atom Different in Textbooks?

    The question is like this: The solution is like this: However, according to the equation for ##E_{dip}## , what I think is that it should be: $$E=\frac {1}{4 \pi \epsilon_o} \frac {qd}{d^3} \hat {\mathbf z} $$, where I take the centre of the sphere in figure 2 as the centre of the...
  44. cwill53

    Electric Field and Continuous Charge Distribution

    I sort of understand the meaning of this integral, but I don't know how to evaluate it. I have never evaluated a volume integral. It would be very helpful if someone could explain in other words what this integral means and give an example evaluating it. This is from Purcell's Electricity and...
  45. aspodkfpo

    What happens when an uncharged object is brought into an electric field?

    Tecd
  46. preachingpirate24

    Electric Field inside the material of a hollow conducting sphere

    Let's say I place a positive point charge inside a hollow conducting sphere. If we take a Gaussian surface through the material of the conductor, we know the field inside the material of the conductor is 0, which implies that there is a -ve charge on the inner wall to make the net enclosed...
  47. dRic2

    I Electric field inside a Superconductor

    I was reading chapter 3 of this book https://blackwells.co.uk/bookshop/product/Superconductivity-by-James-Arnett/9780198507567, which is a brief introduction to superconductivity. It is stated that inside a superconductor the Electric filed is always zero. This is deduced from the equation...
  48. Tony Hau

    What is the meaning of electric field "immediately outside the surface"?

    Today when I am reading Griffith's electrodymamics on surface charge and force on conductors, I have come across two very ambiguous terms: electric field at the surface and immediately outside the surface. The context of these two words is as follows: The electric field immediately outside is...
  49. A

    Calculation with this electric circuit (battery and resistors)

    Hey, I am struggling a bit, als I try to solve this problem - I‘d say all five statements are correct, but it is said, that one must be incorrect
  50. J

    I Changing the effective mass of an electron using electric potentials?

    The Dirac equation for an electron in the presence of an electromagnetic 4-potential ##A_\mu##, where ##\hbar=c=1##, is given by $$\gamma^\mu\big(i\partial_\mu-eA_\mu\big)\psi-m_e\psi=0.\tag{1}$$ I assume the Weyl basis so that $$\psi=\begin{pmatrix}\psi_L\\\psi_R\end{pmatrix}\hbox{ and...
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