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. K

    Two spring-coupled masses in an electric field (one of the masses is charged)

    Here's what I've tried. First of all, I assume that q is positive. For particle A, then, I can write $$q E -k {\left( x _{A }-x _{B }\right) }=m \ddot{x }_{A }, $$ where ##x _{A } ## and ##x _{B } ## are the coordinates of the particles relative to their equilibrium positions from the point of...
  2. du_768

    How can the electric potential be constant between two points in a wire?

    Homework Statement: circuits - terms Relevant Equations: - How exactly can the electric potential be constant between two points in a wire; (assuming that it is electron current); if the electron is moving from a region of high electric potential to a low electric potential because of the...
  3. Irvin Atkins

    B Move in Space without mass exchange

    I did a thought experiment and I can't figure out what the mistake is. There is a system of 2 electric motors weighing 1 kg each with batteries in the Earth's orbit. The motors are rigidly connected by a 1-meter-long bar. If one motor starts rotating in one direction on a signal, the entire...
  4. jack action

    Electric Mining Equipment

    It seems that electric mining equipment is all the craze right now: Liebherr electric excavator Caterpillar 240-ton electric haul truck Liebherr and Fortescue partner on world’s first autonomous electric haul truck EPCA plans to convert 50-70 mining trucks to electric power annually Liebherr -...
  5. damarkk

    Electric sinusoidal field on a hydrogen atom - Quantum Mechanics

    Hello to everyone. I have some doubts about one problem of quantum mechanics. My attempt. I need to calculate the coefficient ##W_{ij}=<\psi_i | H' |\psi_j>## where ##H' = -eE(t)z## is a perturbation term in the hamiltonian and ##|\psi_i> = |\psi_{nlm}>##. We have four states and sixteen...
  6. yashraj

    I Does a time varying magnetic field in vacuum produce electric field or not?

    Suppose there is very long current carrying wire. A charged particle is present somewhere around it. The current in the wire varies with time, thus by biot-savart's law there should be time varying magnetic field. I want to know that will this time varying magnetic field produce electric field...
  7. C

    Possible feedback problems of a uni-directional torque

    Hi, I wonder if someone can help with the following problem? We have a sealed box in space and inside the box is an electric motor with the stator attached to the box. The rotor arm is attached to the inner race of a bearing and the outer race of the bearing is also attached to the box. There...
  8. BuggyWungos

    Why does electric potential energy increase if you move against the field?

    My understanding of this question is that, if you have a proton standing against a positive electric field, and move it in the opposite direction of the field, you're putting in work and therefore should have greater electric potential energy. But that idea breaks down when you consider a...
  9. Heisenberg7

    How to Apply Derivatives in Physics Problems?

    I would like to discuss a few ways to apply derivatives in physics (I don't understand it fully). I don't need a full solution, I only need to understand how to successfully apply the derivatives First example, Thin insulating ring of mass M, uniformly charged by charge ##+q## has a small cut...
  10. BuggyWungos

    Solving for potential using surface charge density of a sphere

    surfafce area = 0.502 E = -q/A2(en) = 3800 -q = 3800*(A2(en)) -q = 1.68*10^(-8) -q = 3.37*10^(-8) V = kq/r V = (9.0*10^9)(-3.37*10^(-8))/0.2 V = -1519 V
  11. kirito

    Find the electric field between 2 finite discs

    I did make the problem simpler by looking at the the part from d/2 down the upper plate here are my initial parameters I am making my size step be h since lowering it may make calculating harder I am especially getting weird results for the field and capacitance R = 0.1; % Radius of the...
  12. Heisenberg7

    B Electric Field Inside a Hollow Sphere

    Let's assume that we have a hollow sphere with holes at opposite ends of the diameter. What would be the field inside the hollow sphere? I know that we can look at this as the superposition of the hollow sphere without holes and 2 patches with opposite surface charge density. For some reason, in...
  13. S

    Electric field of point along the central vertical axis of a triangle

    here is my attempted solution. ## d^2 = z^2 + \frac {L^2} {3} ## ## C ## is coulomb constant since the point is symmetric, only the vertical component of the electric field remains. So, $$ E = 3 E_y =3 \frac {C Q cos \theta} {d^2} $$ $$ E= 3 \frac {C Q z} {d^3} $$ thus part (a) is done ( i...
  14. Heisenberg7

    B Electric Field Created by 2 Infinite Plates

    Today, I watched a video about electric field created by an infinite plate by Khan Academy. They were talking about the clever application of the Gauss's law in this case (the cylinder method), so I wondered if I could apply the same thing but to 2 plates. For example, let's say that the plates...
  15. tellmesomething

    What is taken as datum level for the following absolute potentials?

    We take out "formulas" for electric potential from the relation $$V=\int E.dx$$ Some general formulas are : For a hollow sphere : ##\frac{Q} {4π\epsilon_0 x}## when x>R, x =distance of that point from the center And the problem is we just input the distance in sums to calculate absolute...
  16. Zayan

    Electric Field of a quarter ring

  17. aliinuur

    B E-field of a constant velocity charged particle

  18. kirito

    Why are the electrostatic field lines normal to a charged conductor?

    I understand the following .a conductor is made of atoms and atoms always strive to be at equilibrium and that's why the electric field inside a conductor is zero because the electros distribute themselves in such a way so that they are in equilibrium , yet they do produce an electric field...
  19. kirito

    Electric field of a sphere and a shell

    q encolsed =0 Second case q enclosed q by gauss law At 2r
  20. P

    I Help understanding Maxwell's Equations please

    I have having trouble understanding Maxwell's Equations. Can anyone recommend some good book or website that can help me to understand these Equations? How can electric and magnetic fields travel perpendicular to each other? What causes electromagnetic waves to first radiate from its source? I...
  21. arivero

    A Why do the proton and electron have equal and opposite electric charge?

    The most common explanation I know is that anomaly cancelation implies the sum of electric charges of each particle must cancel generation-wise, so 3 Q(Up) + 3 Q(Down) + Q(electron) = 0, and electroweak doublets imply Q(Up) - Q(Down) = Q(neutrino) - Q(electron), so with Q(neutrino) = 0 it solves...
  22. PhysicsEnjoyer31415

    I Equality of Gravitational and Electrostatic force

  23. tellmesomething

    Find the electric field at a point in 3 dimensional space

    I tried resolving the semi infinite rods into arcs of 90 degree each placed on the three axes but that doesnt take me anywhere.... Alternatively I tried finding out the field at the point due to each rod but im unable to find the perpendicular distance from the point to the rod...I dont think...
  24. tellmesomething

    Prove that the field due to a circular arc is same as its bounded tangent at the centre of curvature

    Lambda = charge density I tried first taking out the field due to the circular arc and I got $$ (lambda / 4π (epsilon knot) ) (2 sin (theta)) $$ For reference this is the arc that was provided in the question of angle 2(theta) and the tangent What I dont understand is how can the fields be...
  25. tellmesomething

    Electric field vector equation: Finding the neutral point for two charges

    This is the general suggested approach given in a textbook. My question is why can I not directly write it in vector form? E1 vector + E2 vector =0 should be valid no? Why are they choosing to write E1 mag + E2 mag=0 Then find a vector form Then convert the magnitude equation into a vector...
  26. B

    Physics about electric circuits: Changing the resistors changes the currents

    Please help me with this homework! I haven't had any solutions since it is all unclear.
  27. srnixo

    Gauss' law and the potential V (plane layer case)

    Here is the exercise: And these are my attempts: This is for the first question about the electric field. (I know I'm missing the drawing, which is a drawing of the plane layer of thickness 2e with a cylinder on it as a GAUSS SURFACE ). As for the second question, I'm not sure about it, so I...
  28. P

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  29. aryan kumar pandey

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  30. Ben2

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  31. L

    Gauss' Law for a conducting / non-conducting sheet

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  32. L

    Direction of electric field vector on the surface of charged conductor

    Consider a negatively charged spherical conductor. On the surface of it, what is the direction of its electric field? Well, the definition of the direction of an electric field is the direction a positive test charge would go if placed at that point. But... it wouldn't move anywhere! So is the...
  33. J

    Solar panel conundrum -- Not enough power?

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  34. Krazen017

    How can I find the sustain time of an electric guitar?

    How can I find the sustaining time of an electric guitar? The influence of other components besides the strings can be neglected. I need it for my term paper.
  35. A

    I Electrical breakdown in air in the presence of a single charge

    Suppose there is an electric charge of 350 micro coulombs in space. The electric field at a distance of less than one meter will be more than 3,000,000 volts/meter considering that this field is greater than the electric breakdown of air and the charge has no place to discharge, what happens...
  36. Gunther_Guss

    Node analysis problem: 2 Current Sources and 3 Resistors

    -
  37. .Scott

    Cement Capacitors based on carbon black and concrete for use in energy storage

    A recent article published in the Proceedings of the National Academy of Sciences (PNAS) describes a large electric capacitors based on carbon black and concrete. The device would be used for electric power storage - often in proximity to the electric power demand, for example, a home.
  38. EleSuki

    B Frequency of EM Waves from Monitor for Black/White & Color Images

    I am using an old monitor (MITSUBISHI RDT27IWLM). The power consumption changes when the screen is white or black, but does the frequency of the weak electromagnetic waves emitted from the monitor change? Or is the frequency the same, only the output is stronger/weaker?
  39. paulimerci

    Find the magnitude of the electric field at point P

    There are two identical spheres with the same charge that are the vertices of an equilateral triangle. ##+3 \mu C## will exert an outward electric field, which is drawn in the FBD below (see the attached pic), Since the horizontal force components (1x and 2x) are equal and opposite at point P...
  40. paulimerci

    Find the magnitude of the electric force from 3 charges at vertices of a cube

    There are three charges with +1 μC and −1 μC, are placed at the opposite corners of a cube with edges of length 1 cm, and the distance from P to B is 1cm 2. I labeled them as A, P, and B, which is shown in the diagram below. Since we need to find the magnitude of the charge at point P and the...
  41. R

    B Exploring the Electric Field of a Moving Charge

    How does an electric field of a moving charge, for example a moving electron, inside a wire looks like? Does it looks like this with distorted circular radial lines?
  42. M

    Electric field amplitude question regarding intensity calculations

    My question is specifically with calculating the intensity. The book solution is I=P/(4*pi*r^2) but would this not give me a weaker electrical amplitude in the final calculation after plugging it in to I=(1/2)*√(ε0/μ0)*(E02) ?
  43. Ahmedbadr132

    Power Efficiency of Linear Piezo Electric Motors

    Hi I want to know the power efficiency of linear piezo electric motors in percentile.
  44. L

    Divergence of the Electric field of a point charge

    Hi, unfortunately, I am not sure if I have calculated the task correctly The electric field of a point charge looks like this ##\vec{E}(\vec{r})=\frac{Q}{4 \pi \epsilon_0}\frac{\vec{r}}{|\vec{r}|^3}## I have now simply divided the electric field into its components i.e. #E_x , E-y, E_z#...
  45. N

    I Electric Field Shielding by Conducting Sheets

    Dear Experts, When a thin conducting sheet with no charge on is placed at a certain distance from a point charge, does it shield the electric field caused due to the point charge from reaching the other side of the sheet. As an extension of that idea, when a conducting sheet or slab is placed...
  46. V

    Equipotential surfaces for an electric dipole

    The answer is given as (a), but I think it's not correct based on the equipotential surfaces diagram given in our book for an electric dipole as below. The red dashed lines, which are supposed to be the equipotential surfaces, are surely not representing a sphere centred at the dipole center...
  47. V

    External forces required to move an electric dipole quasi-statically

    If the dipole is to be in equilibrium at all positions as it's moved so that it's always inclined at 60° to the horizontal, then the torque due to electric field needs to be balanced by torque due to external forces ##F_{ext}## as shown in above diagrams. But such external forces will not make...
  48. K

    Calculating electric charge from graph (capacitor)

    Apparently, we need to integrate the functions from 0 to the time when it is fully charged. However, I integrated in terms of t so the soultion (according to a graph programme) should be around 236 Vs but I don’t see how this could help me.
  49. yucheng

    I Electric potential and potential difference

    Electric potential = "absolute potential" Textbooks usually connect both ends of two capacitors, of different voltages, in parallel. What would happen if we only connect one end of the capacitors? Perhaps we would have to solve for Maxwell's coefficients of potential for these two cases (to...
  50. K

    A Two level system in a thermal noise electric field

    Hello! I have a 2 level system with a dipole moment d. I want to simulate numerically the evolution of the system under an external sinusoidal electric field (far off resonant). This is straightforward using SE. However I also have on top of that another electric field, created by a coupling of...
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