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. archaic

    Electric fields and conductors

    Hello guys! The electric field created by a conductor at a point $M$ extremely close to it is ##\vec{E}=\vec{E_1}+\vec{E_2}## where ##\vec{E_1}## is the electric field created by such a tiny bit of the conductor that we can suppose it to be a plane, and since ##M## is extremely close to the...
  2. atommo

    Stupid question relating to electric induction

    Hi, I've been interested in the science behind electrons/magnetism for quite a while. I've been learning quite a bit from various sources online. However there is one thing that's really nagging me. Magnetic fields result from moving electrons. That indicates that a permanent magnet has...
  3. MeAndMyLucidLife

    Electric Power - Which formula to use and when?

    Homework Statement : [/B] If the length of the filament of a heater is reduced by 10%, the power of the heater: Options are- a) increases by about 9%. b) increases by about 11%. c) increases by about 19%. d) decreases by about 10%. Homework Equations : P[/B]=I2R Or P=V2/R Where P=power...
  4. R

    Electric Potential on the axis of a truncated cone

    1.Data: We have an truncated cone with a volumentric charge density ρ, and it's uniform. The image show the truncated cone and show some info of the radios. 2. Question. We need to calculate the potential on the vertical axis. note: adding an image of the problem but it's in spanish, hope...
  5. H

    Calculate Net Electric Field at Point P | Two Charges 42cm Apart

    Homework Statement Two charges, one of 3.2 x 10 ^ -9 C, the other one of -6.4x10^-9 C are 42 cm apart. Calculate the net electric field at point P, 15 cm from the postie charge, on the line connecting the charges (+) -------------(Point)---------------------- (-) 15cm...
  6. Haddon

    Calculating the magnitude of an electric field

    Homework Statement An electron enters the lower left side of a parallel plate capacitor and exits precisely at the upper right side (just clearing the upper plate). The initial velocity of the electron is 7*10^6m/s parallel to the plates. The capacitor is 2cm long and its plates are separated...
  7. T

    Electric field of a non-conducting sphere

    Homework Statement A solid non-conducting sphere of radius R carries a uniform charge density. At a radial distance r1= R/4 the electric field has a magnitude Eo. What is the magnitude of the electric field at a radial distance r2=2R? Homework Equations Gauss's Law: ∫EdA=Qencl / ε0 Charge...
  8. A

    Time-varying electric field measurement using dipole

    Hello, I am trying to measure the time-varying electric field of a parallel plate capacitor using short dipole antenna, but my numbers are off by almost 100 times. I have a parallel plate capacitor, A=23cmx11cm, d=10cm. I apply 10sin(2pi*1KHz) and 10sin((2pi*1KHz)+180deg) to each plate. I am...
  9. S

    How spacecrafts discharge static electric charge

    I was wondering how spacecraft s discharge when encountering van allen belts (for example the juno spacecraft around jupiter) since obviously there is no earthing and is it possible to remove excess charge to power something on the craft?
  10. K

    Conceptual Issue RE: electric potential difference

    Homework Statement My main conceptual issue here surrounds positives and negatives as they apply to electric potential difference. I will post two questions that illustrate my confusion, if that's ok. 1) The electrons in an old TV picture tube are accelerated through a potential difference of...
  11. A

    Efficiency of an Electric motor pulling a truck up an inclined plane

    Homework Statement See picture. Homework EquationsThe Attempt at a Solution I tried at first just doing (1/3)*(48kJ) to get the energy dissipated, but that would i=give me 16kJ
  12. rpthomps

    Comparing 100J and -100J of Electric Potential Energy

    Is the 100 J of electric potential energy actually greater than -100 J of electric potential energy?
  13. H

    Calculating the final velocity of a simple electric train

    I am currently in grade 12, and for a physics project (a huge project, which gets assigned to you at the start of the semester and needs to be completed just before exams. You think up your project, make a proposal for it and you prove your hypothesis to be right after a presentation and lab...
  14. Adesh

    How to prove that electric field propagates like a wave?

    I was studying Feynman Lectures on Physics Volume 1 chapter 29. In there he proves that electric field propagates like a wave. Here is my attempt (in image), please tell me my mistake. Thank you
  15. physics girl phd

    Solving Electric Potential Difference in a Linearly Varying Field

    Homework Statement I'm trying to do a problem two ways, and things aren't consistent, finding the electric potential difference in a linearly varying field. The electric potential difference between two points is often summarized in texts as ΔV = Vf - Vi = - ∫ E⋅ds where the lower bound of...
  16. L

    At what point is Electric Potential zero

    1. The problem statement Two charges of 3μC and -2μC are placed 2cm apart. At what point along their connecting line is electric potential zero? Homework Equations Electric potential superposition Φ=Φ1-Φ2 since q2 is negative Φ=kq/r^2 The Attempt at a Solution Let’s say the charges are on the...
  17. H

    Voltage and electric field in capacitor

    1. We've been given a spherical capacitor with radius of 1 cm for inside electrode and 2 cm for outside electrode. Voltage between electrodes is 360 V and the task is to find largest and smalles electric field strength in capacitor.2. I'm not sure how voltage given in capacitor works and how to...
  18. K

    Is Electric Potential value classical?

    There is no absolute electric potential. Is it due to classical ignorance (because we don't know the static fields, capacitive coupling, etc. of the surrounding environment) or is it due to quantum ignorance (the potential can fluctuate to any value due to HUP)? My question is valid because...
  19. Clara Chung

    Metal sphere in an electric field

    Homework Statement The question is exactly the same as this question https://physics.stackexchange.com/questions/250297/metal-sphere-in-a-uniform-electric-field However, it says "Then by symmetry the entire xy plane is at potential zero" in the book. I don't understand this. Homework...
  20. Ivan Hu

    Electric Field due to dipole - solution check

    Homework Statement Hi guys, my exam is in four days and my tutor for the electromagnetic module is neither very active nor very competent, so I would like you guys to check my solution for this question. I am afraid I might have messed up some signs or some linear algebra. Homework Equations...
  21. G

    Ratio of the Electric field to the Magnetic field

    Dear all. I would like to know the general expression of the ratio of the electric field strength E to the magnetic flux density B. I know E/B = c, where c is the speed of light, for a vacuum, but I want to know if this is stil valid for any material where the electric and magnetic fields are...
  22. thariya

    A Quantization of the electric field inside a box

    Hello all, The second quantization of a general electromagnetic field assumes the energy density integration to be performed inside a box in 3D space. Someone mentioned to me recently that the physical significance of the actual volume used is that it should be chosen based on the detector used...
  23. P

    How to Calculate Electric Potential in a Split Metal Pipe?

    Homework Statement We have the cross section of a metal pipe that has been split into four sections. Three of the sections have a constant electric potential, Vo. The fourth section is grounded so electric potential is zero. We are looking for electric potential inside and outside of the pipe...
  24. B

    Calculating Electric Displacement in Dielectric-Filled Capacitor Slabs

    Homework Statement Introduction to Electrodynamics (4th Edition) By J Griffth Ch.4 Problem 4.18 The space between the plates of a parallel-plate capacitor is filled with two slabs of linear dielectric material. Each slab has thickness a, so the total distance between the plates is 2a. Slab 1...
  25. S

    Wood/Glass/Metal Video about modifying a new Ryobi electric hand planer

    This is an interesting video where a shipwright shows how to modify a new Ryobi electric hand planer to correct some of its defects.
  26. bob012345

    I Electric & Magnetic Fields Inside Conducting Wires

    Suppose a straight current carrying wire is immersed in a uniform electric field along its axis. For this problem, please don't worry about complete loops or return paths, just consider a segment of straight wire carrying a current. Since external electric fields don't get inside conductors due...
  27. G

    Net Electric field due to 3 charges

    Homework Statement There is a 3nC charge at (-3,0), -6nC at (0,2) and 5nC at (1,0). What is the electric field at the origin (0,0)? Homework Equations ##E = \frac{Q}{4 \pi \epsilon_0 r^2}## The Attempt at a Solution i think its ##(\frac{1}{4 \pi \epsilon_0})(-\frac{14}{3} i - \frac{3}{2} j)##...
  28. Shivang kohlii

    Engineering An electric bulb of 500 W at 100v is used in a circuit

    If the circuit has 200 V supply. The resistance R that must be put in series with bulb so that it draws 500 w is? 2. Relevent equations P= v^2/r I = v/r 3. My attempt at the solution R= V^2/P r (bulb)= 10000/500 = 20 ohm Now for 200 v supply .. P= 500 W V= 200V Rnet = 20 + R R+20= 80 R= 60...
  29. hugo_faurand

    New materials and ways to store electric energy

    Hello everyone ! I'm Hugo. I'm a french high school student. This year I've a project on new way to store electricity and their materials.I've done researches on super capacitors. But I've found only that "new way" to store electric energy. And for the material part, I don't know what I can...
  30. E

    The sign of F (dot) dl when finding electric potential

    The electric potential can be defined as V = - ∫C E⋅dl where we are taking the line integral along C from some convenient reference point O, where we have set V = 0, to the point r we are trying to find the potential at. Of course, C can be any curve, but it's usually the most convenient to...
  31. B

    Dipole problem with electric fields

    Dipole problem (which is solved through mirror imaging) has been troubling me with its solution. I understand everything except how the dipole moment's coordinates came to be, since when converted into x-y axis, its doesn't make sense. (problem 4.6) The screenshot contains the solution which...
  32. B

    Electric field of "half" an infinite charged sheet

    Homework Statement A charged sheet with charge density ##\sigma## is described by ##-\infty<x<0,-\infty<y<\infty, z = 0##. Find the electric field at ##(0,0,z)##. Homework Equations Electric field of continuous density charged body from the Coulomb law: $$E = \frac{1}{4\pi...
  33. B

    Calculating the Electric Field outside a dielectric

    In the textbook (Introduction to Electrodynamics by Griffiths), the problem in the attached image asks to find the electric field ##E## outside a dielectric. The problem consists of dividing the electric field into the one produced by the negative charges in the dielectric and another by the...
  34. B

    Electric Field and Potential in a conductor

    So in my textbook (Introduction to Electrodynamics by Griffiths) it said that inside a conductor, the electric field E would have to zero, since if it wasn't the free charges would move accordingly and create a electric field that cancels the original field. But in a question that soon followed...
  35. S

    Electric current flowing in a power transmission line

    A cable of resistance 12 Ohm carries electric power from a generator producing 250 kilowatt at 10,000 volts. Calculate the current in the cable. Solution using P=VI I=25A but using P=I^2R 250000=I^2×12 I =500/root 12 Amps What is the reason for the different...
  36. YMMMA

    What causes electric field/ magnetic field?

    Homework Statement What causes electric field? What causes magnetic field? (I) stationary electric fields (II) moving electric charges (III) a changing magnetic field IV) a current-carrying wire Homework Equations E=F/q B=μI/2πr E electric field F elecric force Q charge B magnetic field I...
  37. Silentwhale

    Electricity and magnetism: Electric Field for Two Long Charged Lines

    Homework Statement Given two very long lines each is charged with linear density +lambda Coulombs/meter. The two lines are separated by a distance of d metres. A) show the electric field E, at any point along one of the lines due to the other line is E = lambda/(2 (pi)(epsolon o)(d)) (Note...
  38. J

    Design a Handheld Electric Field Meter with Arduino

    Hello, I want to create a handheld electric field meter to measure the strength at a certain point with an arduino. I have seen various ideas online but I am still not sure what kind of design to use. Is the right concept to use two antennas. Measure the voltage on each and then calculate the...
  39. YMMMA

    Where is the electric field greatest in magnitude?

    Homework Statement In the file Homework Equations No equations needed The Attempt at a Solution I answered it C. Since I learned that at the tip there are most of the charges. Therefore, it’s the point of the greatest E field magnitude. But another tutor told me that it is a circle, and...
  40. HotFurnace

    Electric Potential Distribution in a Vacuum Diode

    Homework Statement This problem is belonging to a book, which is material for Vietnamese students who will take part in IPhO (International Physics Olympiad). Since this problem is written in Vietnamese, I will try my best to translate it to English: A vacuum diode consists of two parallel...
  41. A

    An electron & a proton are each placed in an electric field

    Homework Statement An electron and a proton are each placed at rest in an electric field of 687 N/C. What is the velocity of the electron 56.5 ns after being released? Consider the direction parallel to the field to be positive. The fundamental charge is 1.602×10−19 C, the mass of a proton is...
  42. L

    Electric Field Inside Concentric Spheres

    Homework Statement Homework EquationsThe Attempt at a Solution I am having trouble figuring out why the answer is A) the electric field points radially between A and B. I think it is because since the point between A and B is mostly negative, the electric field would point outwords more...
  43. P

    Electric potential energy between charge and moving magnet

    The setup for one magnet Introduce a magnet: Inertial Frame 1 (or lab frame) A frame where a magnet is seen to move with uniform velocity v and carries a uniform polarization P while a point charge Q is seen to be stationary at time t=0. Inertial Frame 2 (or material frame) A frame where a...
  44. L

    Electric Potential Integral Question Confused

    Homework Statement Homework Equations E=KQ/R^2 The Attempt at a Solution I'm kinda confused at what the question is asked. It is in terms of x, but I thought the integral for potential is V=int(Edr)? Also, should it be integration starting from infinity? Why is the integration from -2 to 3...
  45. E

    How to Determine Electric Flow Through a Square Surface Due to a Nearby Charge?

    Homework Statement determine the electric flow through a square surface of side 2l due to a load + Q located at a perpendicular distance l from the center of the plane I really don't know how to answer this question .i need help guys Thanks Homework EquationsThe Attempt at a Solution I ended...
  46. L

    Electric Potential at Radius R of Concentric Spheres

    Homework Statement Homework Equations V=kQ/R The Attempt at a Solution The answer is B)kQ/R. It is because V= k(2Q)/R. I don't understand why Q=2Q in this case. Isn't the point on the inside of the outer shell, so the Q for the equation is just Q?
  47. starstruck_

    Electric field of spherical shell

    Homework Statement Consider a spherical shell with uniform charge density ρ. The shell is drawn as a donut with inner (R1) and outer (R2) radii. Let r measure the distance from the center of the spherical shell, what is the electric field at r>R2, R1<r<R2, and r<R1. I am working on the r > R2...
  48. cookiemnstr510510

    Calculate the electric field in all of space for a non conducting sphere

    Homework Statement A) Use Gauss's Law to derive the electric field in all space for a non-conducting sphere with volumetric charge distribution ρ=ρ0r3 and radius, R. B) Repeat when there is a concentric spherical cavity within the non conducting sphere with radius, A. Homework Equations...
  49. cookiemnstr510510

    Derivation of electric potential charged disk from ring

    Homework Statement a)recall that electric potential is a scalar quantity. For a circular ring of radius, R', carrying charge, Q, what is the electric potential at a height,y, above the center of the ring? b)Use your above answer to determine the electric potential at a height,y, above the...
  50. cookiemnstr510510

    Electric Potential Equations: Understanding and Applying in Non-Uniform Fields

    Homework Statement Hello, I am wondering if I am thinking about electric potential correctly: Stop me if I am wrong: V=electric potential, the electric potential is created by source charges altering space around them. If you place a test charge, q, within that space we can say it experiences...
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