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. Jon Zimmer

    Relation between electric motor and battery current, peak etc.

    Good afternoon guys, I was making some researches about building my own EV and its' specifications but I have a few no direct answered questions and some of them I humbly ask the help for you guys, based on the configuration example below. Considering that I hypothetically have an electric DC...
  2. mcastillo356

    Verifying Coordinate System for Electric and Magnetic Forces

    The attached file is the coordinate system I've used a) $$\vec{E}=\dfrac{\vec{F_e}}{q}=\dfrac{1,10\cdot{10^{-13}}\hat{j}\;N}{1,6\cdot{10^{-19}}\;C}=6,88\cdot{10^5}\hat{j}\;N/C$$ b) $$\sum{\vec{F_{net}}}=\vec{0}=\vec{F_e}+\vec{F_m}$$...
  3. speaknow

    Continuity equation of the electric field

    According to the continuity equation of the electric field (i.e., ▽·Ε = 0) a decrease in cross-section area will increase the electric field strength, Why is that?
  4. J

    I Equivalence principle: an electric charge and a coil

    The near-range magnetic field ##\vec{B}## of a point charge ##q## at distance ##\vec{r}##, moving at a non-relativistic velocity ##\vec{v}##, is given by $$\vec{B}=\frac{q}{4\pi\epsilon_0c^2}\frac{\vec{v}\times\hat{r}}{r^2}.$$ Faraday's law of induction for the induced EMF ##V_c## in a coil...
  5. curiosissimo

    Electric field in a spherical shell

    So for the Gaussian theorem we know that $$ \frac{Q}{e} = \vec E \cdot \vec S $$ Q's value is known so we don't need to express it as $$Q=(4/3)\pi*(R_2 ^3-R_1 ^3)*d$$ where d is the density of the charge in the volume. I've expressed the surface $$S=4\pi*x^2$$ where x is the distance of a point...
  6. M

    Electric Field of Point Charge at y=r and an Infinitely Long Cylinder

    Let point charge q be at y=r. Let there be an infinite conducting plane along the x-axis and z-axis that is neutrally charged. In this case, the method of mirror charges can be used. The plane is replaced by a point charge -q at y=-r. The electric field for y > 0 is the same in both cases...
  7. C

    Do any electric lights have statistical lifetimes X~Exp(λ)?

    I've come across a number of problems in elementary probability theory and statistics that can be exemplified as follows: Naturally, real lamps decay over time, so their lifetimes can't be memoryless. With that being said, is the exponential distribution a good approximation for the...
  8. A

    Are electric circuits considered as electrostatics or electrodynamics?

    Thanks in advance!
  9. A

    How does electron speed affect electric power?

    I've got a quick question on the relationship between the kinetic energy of individual electrons and the total electrical energy they create. I have a radioisotope - a beta emitter - which produces electrons with around 1 MeV (1.60218×10-13 Joules / 4.45049×10-17 Watt-hours) of energy. I keep...
  10. hairey94

    What are the assumptions for solving the charged conducting disk problem?

    Not sure how the problem set up initially as no diagram was provided in the question. Please help me to start with the solution. Your assumptions and educated guess are appreciated.
  11. mcastillo356

    Increasing electric potential and electric field

    Hello everybody! I want to check out if I've solved correctly: ##\Delta{V}=-E\Delta{x}## ##\dfrac{\Delta{V}}{\Delta{x}}=-E## ##\dfrac{15\;V}{10^{-2}\;m}=-E## ##1,5\times{10^3}\;N/C=-E## ##\vec{E}## direction it's oriented into the XY plane Thanks!
  12. J

    Electric field produced by a uniform charge density on a wall

    I couldn't solve the question. Can you help me?
  13. J

    How Do Kirchhoff's Laws Help Calculate I1, I2, and I3 in a Circuit?

    According to the circuit in the figure; Can you calculate the values of the currents I1, I2, and I3. Can you send me a detailed solution to understand?
  14. Flaming Physicist

    Electric force between two equal parallel rings of charge

    The problem is symmetric around the z axis, thus the force must be in the z direction only. I tried dividing both rings into differential elements, then integrating through the upper ring to get the z component of the total force on the upper ring due to a differential element of the lower ring...
  15. DerbisEternal

    How do I proceed with two different trig functions containing x on the left?

    Given the total angles in the x direction, I set up this: (mg/cos(x))*sin(x)-Fe=0 then isolated for x: mgtan(x)=(kq^2)/(2*sin^2x) sin^2(x)*tan(x)=(kq^2)/(2mg) From here I am stuck. How do I go forward when x is contained in two different trig functions on the left?
  16. tanaygupta2000

    Electric field inside a spherical cavity inside a dielectric

  17. E

    Electric field within a battery

    I've been reading through this paper to try and get a better understanding of how batteries work. The analysis there is fine (they consider a voltaic cell to charge a capacitor in order to derive ##\Delta V=\varepsilon##, and go via an energy route), but it doesn't really touch upon the fields...
  18. R

    Electric field at (0,0) for this charged square conductor

    Can we assume that square charge resembles a sphere shell, and think like electric field at sphere shell's center is 0.
  19. Y

    Electric potential:Potential difference of test charge

    Electric potential energy at initial: Ee=kq1q2/r =(9 ×10 ^9×1.5×10^-6×(-5)×10^-6)/0.1 =-0.675J Electric potential energy at the closer point: Ee=kq1q2/r =(9 ×10^9×1.5×10^-6×(-5)×10^-6)/0.05 =-1.35J Δv=ΔEe/q =(-1.35+0.675)/1.5×10^-6 =4.5×10^5V or: Initial position...
  20. H

    Electric dipole moment vs electric current dipole moment

    I have to estimate the electric dipole moment of an NV center in units of Am. I know that for a regular electric dipole moment it can be estimated using p=ed. With e=1.6*10^-19 and d=0.1 nm (interatomic distance), this however is in units Cm. I don't know how to go to Am
  21. F

    Electric current is not a vector while electric current density is a vector

    Why is electric current not a vector while electric current density is a vector? What's the intrinsic difference between the two through that surface integral?
  22. MARIAM507

    Electric circuit -- Ohm's second law

    I want to know ohm's second law i search many times about it but every time the result is about ohm's first only, so can anyone help me??
  23. G

    Modulus of the electric field created by a sphere

    I think the right solution is c). I'll pass on my reasoning to you: R=6\, \textrm{cm}=0'06\, \textrm{m} \sigma =\dfrac{10}{\pi} \, \textrm{nC/m}^2=\dfrac{1\cdot 10^{-8}}{\pi}\, \textrm{C/m}^2 P=0'03\, \textrm{m} P'=10\, \textrm{cm}=0,1\, \textrm{m} Point P: \left. \phi =\oint E\cdot...
  24. G

    Electric field and electric potential exercise

    a) \vec{F}=\vec{E}\cdot q \phi =\oint \vec{E}d\vec{S}=\oint \vec{E}d\vec{S}=\underbrace{\oint \vec{E}d\vec{S}}_{\textrm{FACES } \perp}+\underbrace{\oint \vec{E}d\vec{S}}_{\textrm{FACES } \parallel}=0+\oint EdS\cdot \underbrace{\cos 0}_1= E2S \dfrac{Q_{enc}}{\varepsilon_0}=\phi \left...
  25. D

    How to Determine Values of α0 and α1 for Electric Polarizability?

    Hello everyone, I've got my non-uniform electric cloud distribution formula given by: ## \rho(r) = \frac {-Ze} {\pi a^3} e^{-{2r}/a}## Where ##Z## is the atomic number of the atom in question and ##a## Bohr's radius and ##E_L## the local electric field. Considering the previus expression ...
  26. P

    Electric field at the center of a sphere

    My first impression was the electric field is 0 at the center of the sphere, but it turned out not the case. My understanding when problems refer surface charge density, is that the charge exists only on the surface and it is hollow inside the sphere. Am i correct? Using the electric field...
  27. zoyash

    Electric Current and Resistance

    I have attached my solution to this problem but I think I got the wrong answer.
  28. KC374

    Work Done by an Induced Electric Field

    I have drawn a picture of what the induced electric field will look like, and I have determined its magnitude both within and outside of the magnetic field. I was able to get the right answer for part (b) with this information, but I don't understand why the answer for part (c) is 0 J. It...
  29. P

    Electric field due to a straight rod

    The net electric field is ## 2dE \cos\theta ## ## dE = \lambda dx/(4\pi\epsilon (x^2 +r^2)) \\ 2dE \cos\theta = 2r\lambda dx /(4\pi\epsilon (x^2 +r^2)^\frac 3 2) \\ E_{net} = 2\lambda r /(4\pi\epsilon) \int_0^a dx /( (x^2 +r^2)^\frac 3 2) \\ E_{net} = 2\lambda r /(4\pi\epsilon) [\frac x...
  30. Zero

    Calculating Electric Field: A Failed Attempt

    I tried getting E by dividing volts and distance since I know the distance between the two plates is .352 m but it did not work
  31. P

    Electric Field of a Point Charge and Thin Ring: A Comparative Analysis

    I thought it was easy but i am not getting the correct answer The electric field due the point charge q is ## E1 = q/(4\pi\epsilon x^2) ## The electric field due to the thin ring of radius R is considering the electric field due to the element charge dq (dS) ## dE2 = dq/4\pi\epsilon (x^2 + R^2)...
  32. F

    The orgin of the superposition principle of electric field

    Isn't the superposition principle of electric field just force being addable? Jackson's electrodynamics says it's based on the premise of linear Maxwell's equations. Which support(s) the superposition principle?
  33. V

    Is an electric superheater radiant or convective?

    Hello everyone, I am dynamically modelling a electric superheater. During the calculation I need to calculate the overall heat transfer coefficient. Can someone tell me which calculation do I need to use to calculate the overall heat transfer coefficient, radiant or convective? Please clear my...
  34. C

    Parameterize Radial Vector of Electric Field due to Spherical Shell

    Homework statement: Find the electric field a distance z from the center of a spherical shell of radius R that carries a uniform charge density σ. Relevant Equations: Gauss' Law $$\vec{E}=k\int\frac{\sigma}{r^2}\hat{r}da$$ My Attempt: By using the spherical symmetry, it is fairly obvious...
  35. E

    Ambiguity when taking the Earth as a zero for electric potential

    When you ground something in electrostatics, the potential of that body becomes the potential of the Earth once equilibrium has been reached. In this context, it is usually taken that the Earth is at 0V. There are two possibilities for this. Either the constant of integration is chosen such that...
  36. cwill53

    Why are my force equations giving me incorrect answers?

    I had made equations for the forces in the x-direction and y-direction, but when solving them they yielded the wrong answers, which makes me think that they were incorrect:##(T_{A}cos60^{\circ}+T_{C}cos45^{\circ})=0## ##(T_{A}sin60^{\circ}+T_{C}sin45^{\circ})=5lbs## Here's the diagram for the...
  37. Astronuc

    History Modern history of diesel-electric and electric locomotives

    I recently came across some good histories of GE and ALCO locomotives. ALCO was the second of the two preeminent steam locomotive manufacturers, the other being Baldwin. Diesel-electric locomotives were replacing steam locomotives, although steam continued through the 1950s, especially on...
  38. P

    Calcualtion of electric potential and radioactive decay

    This is just a representative diagram to visualize Surely a very tough one for me to solve. The number of nickel atoms are not mentioned. if the number of decays are ##3.78∗10^8## and with each decay depositing 100keV. The total energy deposited is ##100keV∗3.78∗10^8=6.048∗10^6## I have to...
  39. Achintya

    What is the reality of the Electric Force & Field?

    Please help. Thank you.
  40. G

    Find the Electric potential from surfaces with uniform charge density

    I do not have the solutions to this problem so I'm wondering if my attempt is correct. My attempt at solution: We have two surfaces which we can calculate the area of. I think we can use gauss law to find the electric field and then integrate the E-field to find the electric potential. So for...
  41. B

    Electric Force and Field homework problem

    This is my homework. And we don't have online lessons. But my teacher gave this for homework. I couldn't solve this problem. Can you help me?
  42. T

    Why will 240 volt condenser kill me but not 7,000 volt electric fence?

    I used to attend an HVAC program at a trade school. One time my instructor and i were working on either the outdoor unit of a split-system heat pump or the condenser of a split-system straight air-conditioner. Even though the unit we were working on was either an "outdoor unit" of a heat pump or...
  43. P

    Electric field in the Spherical Cavity

    a. For the question a the solution is If the uniform charge density is ρ then the charge of the sphere up to radius r is q = ρ * (4/3)*π * r3; Hence the electric field is E = (ρ *4π*r^3)/(3*εο*r^2); E = (ρ*r)/(3εο); b. I don't understand what is superposition? How to proceed? Please advise.
  44. EsinDerin

    Electric Field's Force on a Suspended Plastic Ball

    Hi,I couldn't do this problem.I hope someone could help meths is my first time in this forum
  45. Bilbo B

    Electric potential of a spherical conductor with a cavity

    Summary:: If the conductor is having a cavity and is provided with some charge, with the cavity too having some charge then how the potential will be affected on the outer surface of the conductor. The center of cavity and the center of hollow sphere does not coincide. As if their centers do...
  46. M

    The vector sum of the electric forces exerted on a particle

    r_{13}=r_{23}=\sqrt{(30*10^{-3})^2+(90*10^{-3})^2}=\sqrt{9*10^{-3}}\\ F^E_{13}=F^E_{23}=9E9\cdot\frac{5*10^{-9}\cdot3*10^{-9}}{9*10^{-3}}=1.5*10^{-5}\\ \theta=tan^{-1}(\frac{90*10^{-3}}{30*10^{-3}})=71.565\,degrees\\ \vec{F}^E_{13}=<F^E_{13}cos\theta, F^E_{13}sin\theta> = <4.743*10^{-6}...
  47. D

    Torque calculations for a small electric vehicle

    Hello guys, I'm trying to calculate the torque for a 3 wheeler electric (small vehicle). 2 driving wheels and one driven wheel. At the driving wheels we have a BLDC motor for each wheel. We want to calculate the torque for resting( not going down hill) on inclined plane (angle={5,10,15...
  48. D

    Exploring the Interaction of Magnetic and Electric Fields

    Hello, If you have an appropriately oriented conductive ring in a constantly changing magnetic field, current will flow in the ring. There will also be a magnetic field associated with the current in the ring. I understand (maybe ... ) that the current is due to the electric field which is...
  49. G

    Electric field around a sphere with an internal charge distribution

    I'm just going to skip some of the step since I only need help with understanding the last part. After rearranging the equation stated at "Relevant equation" (and skipping some steps) we will get: E * 4*pi*e0*R^2 = integral pv * 4*pi*R^2 dR E = 1/(4*pi*e0*R^2) * 4*pi * integral pv*R^2 dR E =...
  50. Bell

    What's the direction of electric field in Laguerre-Gaussian beams?

    As for Laguerre-Gaussian beams, the direction of wave vector is helical, and how about the direction of electric field? I found that there was little literature mentioned this.
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