Electricity Definition and 999 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. atommo

    Limit to generating static electricity via contact?

    Let's say you are rubbing a balloon on your hair to make it charged. If you then discharge the balloon and rub it on your hair again (and repeat this process numerous times). Would your hair run out of electrons so eventually you would be unable to charge the balloon, or would your hair gain...
  2. jakiul094

    Is It Logical to Use a Generator to Produce and Share Electricity to the Grid?

    Want to produce electricity from a generator by using the motor driven by electricity suppose 10KW. It will be for only once. When the generator is able to provide suppose 60 KVA, among them I want to share 50KVA to Grid and other 10KVA I will use to run the starter motor. Is that logically ok...
  3. Superposed_Cat

    How can C4 be detonated by heat or shock, only by electricity?

    I was thinking about electroactive polymers, and wondering if any exist that are immune to high temperatures, and although explosive decomposition is a completely different subject, it got me thinking about c4. Chemically speaking, what gives a compound such as c4 the ability to not detonate...
  4. E

    How would electricity be generated from a nuclear fusion reactor?

    How would electricity be generated from a nuclear fusion reactor? How soon do you think that fusion power plants will become a reality?
  5. Steven Ellet

    Looking for a website or app with live chat rooms related to electricity

    I am looking for a website or app with live chat rooms related to electricity.
  6. heatupgrade

    Can we make electricity from heat?

    I am a refrigeration technician with a fascination for heat pumps. I wonder if we can make two systems in parallel. The Carnot heat engine is used to describe the steam locomotive. I want to use a different fluid with a lower boiling point to create a heat engine using a refrigeration cycle...
  7. C

    I RC charging - intuition behind equal dissipated energies?

    Assume that a resistor R charges a capacitor C, whose other terminal is connected to the ground. The charge at time t = 0 is assumed to be null and the supply voltage is equal to V. We have, as is well known, ##i = \frac{V}{R} e^{-\frac{t}{RC}}##. Integrating ##\frac{i^2}{R}## between t = 0 and...
  8. B

    Electricity in transmission lines (Simple V^2/R =P)

    I understand how to get the answer but i don't understand how the answer 0.2 ohms is equal to the resistance of the transmission lines If V^2/P = R then (132kV)^2/800MW = the resistance of the transmission lines, why is the 1% tansmitted as heat relevant at all as this is just one form of...
  9. Dr-LucienSanchez

    Calculate the total resistance by integration using the conductivity equation

    (i) Dividing the rod into thicknesses of dx we get discs of area A with lengths=dx so using (****) we have the resistance of a typical disc (between point x' and x'+dx) as: (1) ##R(x'dx)=\frac{dx}{g(x)A}## (ii) Using (1) and (*) and the integrating from a to b of the entire rod we get...
  10. Renewable_energyguy

    Making electricity by means of my old bike

    going off the summary I want some feedback and any opinion that may improve this project, please and thank you.
  11. callie123

    Can constant electrical current heat water?

    Hi, I'm trying to make a realistic scene, in which water is kept under constant electrical charge. If the power is around 75 milliamps, and it's in a stream about twenty feet across by ten feet deep, would this affect water temperature? Thanks!
  12. Zeynaz

    LDR circuit electricity question

    So far what i figured out is that R2 and R3 are in parallel, R1 and LDR in parallel. And these two parallel circuits are parallel to each other ( tell me if I am wrong) The voltmeter has to read 0 but I am not sure how i can achieve that. Is there a rule where when the resistance of each side...
  13. A

    AC Electricity Generation and Transmission over a Single Wire?

    I'm a bit confused as to why can't you transmit AC current over a single wire. For instance, say you have an AC generator which induces potential difference at different points of the wire and thus, creating current. Downstream, the wire can be split and applied to a load. When the wire is...
  14. Skrphys

    Electricity: Is it a longitudinal wave?

    I am a high school teacher and we were discussing waves and electricity in class today. One of my students asked me if electricity is a longitudinal wave or not and I had no idea how to answer. So, I realize that electric fields are what drive electrons to move through conducting wires, but...
  15. BobbaD

    Creating Electricity: Can Magnets & Capacitors Create More Power?

    Suppose you made a generator by connecting several magnets pushing currents through wires into a capacitor. Now suppose you connected this capacitor to another capacitor by a wire coiled around another wire both connected to the next capacitor. Could this work in creating more electricity for...
  16. callie123

    How easily can a high amperage electric fence be shorted out?

    Researching for a Scifi novel that depends heavily upon electricity...something I don't know much about! Any input would be appreciated! My situation: Somebody is trying to sneak through a high powered electric fence. Is it at all feasible to short out the fence somehow -- like, connecting it...
  17. F

    Engineering Help me finding the current in here please (Circuit analysis)

    Hi! I've been struggling with this. Original exercise here: Find the value of Iy when R=0. And the value of Vx when R is infinite. For the first part of the question I did this since R=0: I've tried to solve this circuit and I get that Iy and I5 are 0 A, and this can't be possible since Iy...
  18. A

    Electrical generation from used water in my home

    Hi everyone. I was just out in my back garden and was watching the water from someone's shower pour down the pipe and out into a drain. I was thinking if all of the used water from my house just goes down a drain then why not try make use of it. If the water system continues after use and takes...
  19. TachyonLord

    Project on Electricity & Magnetism(Topic Suggestions needed)

    So I have taken up this course on Electricity and Magnetism and we need to prepare a project as in not very broad as such but for example, attempting to solve a problem or something that is related to the subject but off the course. I'd like to involve computation too in some form or the other...
  20. SaiTatter

    I need to calculate the equivalent resistance

    Homework Statement The circuit is the one in "Fig.4" I need to calculate equivalent resistance between A and B. This is what I've tried: I think that the first resistor is shorted by that wire connected between A and E. Their answer looks like this, in fig 2.2.1. I'm not sure if their...
  21. arturo

    Potential across a conducting sphere surrounded by an insulator

    Homework Statement A conducting sphere has a radius of 2.25 m and carries a positive surplus charge of 35.0 mC. A protective layer of barium titanate is applied to the surface of the sphere to make it safe for laboratory workers nearby. Safety considerations dictate that the potential...
  22. callie123

    Writing: Input Wanted Electrified Water: Feasibility and Applications

    I'm working on a Scifi novel, and trying to make it somewhat...scientific! Any advice is appreciated. Here's my question: I'd like to write about a situation where a body of water is purposefully kept under electric charge for years on end. This body of water would vary in size and depth, but...
  23. callie123

    Exploring the Intersection of Science and Fiction in My Writing

    I was told to introduce myself before asking a question. So, I'm a writer -- and that's why I joined this forum. My current project is Scifi -- with more "sci" than "fi" at certain points, haha! I AM NOT very scientific, so I'm hoping I can get smart people to answer some questions now and then...
  24. Hawkingo

    What are some good books on electricity and Magnetism

    Can someone please suggest some good books on electricity and Magnetism for graduation in physics? Thanks for helping:smile:
  25. H

    Electric arc: How to calculate the required voltage for a light bow?

    <Moderator's note: Moved from a homework forum.> Calculate the required voltage to produce a electric arc between 2 iron nails (distance: 3cm). I´ve read in the internet that you need 1 kV per mm. But how can I calculate this value, that I need 1kV per 1mm?
  26. F

    Rubber soled slippers generating static electricity

    I started having this problem with wearing slippers (or any shoes with rubber soles) in the house because the rubber, rubs the carpet and charges me up. Anything metal that I touch gives me a mild-nasty shock depending on how charged up I am. I tried different kinds of slippers and socks, I...
  27. A

    B The Gain of the Inverting Amplifier and Virtual Earth....

    This is an inverting amplifier incorporating an ideal op-amp with infinite open loop gain. I have a simple question concerning the derivation of its gain (-R2/R1). The point I circled is at 0V (Virtual Earth) but then, if V+=V-, Shouldn't Vout=0 regardless of what R2 and R1 are?? What's wrong in...
  28. N

    Build an Efficient Electrostatic Generator: Tips, Tricks, and Resources

    Hi all Interested in making an electrostatic generator, anyone have experience of building one and also what type would be the most efficient build induction or friction based? Lots of info on the net regarding the principles but and good books for this or websites? Also how best to...
  29. Abdullah Wahid

    Electricity and electrons in the wire

    If electrons move as current flows through a conductor, what happens when a wire is grounded? Do electrons flow in the ground?? If they do, will it effect the number of electrons in the circuit which starts from power plant such as dam and comes to our homes through a grid station? Will it not...
  30. Subrahmanyan

    Electrical Help finding appropriate equipment

    I would like to measure time period of very short periods of electricity flow in the range of micro seconds or even smaller;can someone tell me me a device that can help me do this?
  31. Akash47

    Why we use the conventional direction for current flowing?

    I often get confused that why we have to use the ancient idea for the direction of current flowing.I have come to know a very weak reason for it.It is said that when current was first discovered,it was assumed that the current flows from the positive region to the negative region(using the idea...
  32. V

    Discussion about Altering Automotive Electricity Management

    I'd like to start a thread of thoughts and opinions of a topic that I am considering spending time and money on. Unfortunately, I do not have a very broad knowledge of the engineering intricacies of the topic. I'm really curious if there has been a proposal or workings of a vehicle that uses an...
  33. S

    Finding the Resistance of a Fault in a Pair of Transmission Lines

    Homework Statement https://www.bpho.org.uk/user/pages/05.past-papers/06.as-challenge/_general/BPhO_AS_2010_QP.pdf 12. A combination of resistors shown below represents a pair of transmission lines with a fault in the insulation between them. The wires have a uniform resistance, but do not have...
  34. Celso

    Power waste (conceptual doubt)

    I'm currently in a undergrad level course of eletromagnetism and my professor found it useful to remember quickly of some relationships that we see in high scool, among them power waste. I got the formulas, since they're simple and are direct derivated from the definitions of electric current...
  35. A

    How Do I Solve This Combination Circuit?

    Could somebody help me out with this combination circuit? The answer that I get is 62K but that is not one of the answers. At first, I thought the 10kohm and 20kohm wherein series and the other side as well. Then I thought they are all in parallel because of the different current flow they all...
  36. Silentwhale

    Electricity and magnetism (Gauss' law)

    Homework Statement Given two things spherical shells radii r1 and r2 with r2 > r1. The inner she'll is charged uniformly with a total charge Q1, while the outer shell with Q2. A) use gauss law to computer the electric field everywhere B) Use any method to calculate the potential everywhere...
  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. YMMMA

    Electricity: 2 charged rods connected to a voltage source

    Homework Statement In addition to the question given in the attached file below, I don’t understand how is the polarity changing periodically. Homework Equations Concept-based question, I guess. The Attempt at a Solution I have no idea how should I approach the question. So, if anyone has an...
  39. A

    Finding Charge & Tension of a Suspended Cork Ball

    Homework Statement A charged cork ball is suspended on a light string in the presence of a uniform electric field. E=(3×10^5 N/C)i+(5×10^5 N/C)j. The ball is in equilibrium in the field. Find the charge on the ball. The acceleration due to gravity is 9.8 m/s2 . The mass of the ball is 0.7g. The...
  40. N

    Electrostatics from particle laden air

    Is it possible to generate static electricity from air flow containing particles example smoke or dust flow, or does anyone know of experiments such as the kelvin water dropper converted to generate static from air flow ? Thanks
  41. BobbaD

    Can a Magnet Charge a Capacitor? Exploring the Possibilities

    Can you charge a capacitor with magnet and wire? Can a wire attached to a capacitor be given amperage by a stationary magnet? Can the wire be made to a short length so that the magnetic field creating the current causes the current to reach the capacitor to charge it? I imagine this doesn't...
  42. R

    What is this LED for in this Electricity Meter?

    Hello What is this led for in electricity meter
  43. T

    What are benefits of Electricity of nuclear power plant

    Hello What are benefits of nuclear power plant electricity than hydro power generated electricity Does it cost less per unit any or the waveform is pure sine wave how engineer build it .
  44. P

    Why don't voltages add up numerically in an LCR AC circuit?

    The attempt at a solution (Assuming the components are in series of this order: resistor, inductor, capacitor So I know that the phases are not in sync, that as the voltage oscillates the voltage across each component in the circuit is different. At the peak voltage aka peak current the voltage...
  45. shahbaznihal

    Spatial dependence of induced Electric field

    The Faraday's law and Lenz's law together give you, $$\xi = -\frac{\partial\phi_B}{\phi t}$$ or put another way,$$\vec{\nabla} \times \vec{E} = -\frac{\partial \vec{B}}{\partial t}$$. My question, I am just asking to make sure, the spatial dependence of ##\vec \nabla \times \vec E## will be the...
  46. shahbaznihal

    Testing Electricity and Magnetism section in GRE Physics

    Hi, I am taking GRE Physics this year and I am preparing from Conquering GRE Physics book and I have covered everything in that book on Electricity and Magnetism (yet to study Optics and Waves). My question: How much from Griffith Electrodynamics book do I need to study? Or is the material in...
  47. José Ricardo

    Post with wireless electricity is it possible?

    A post, each which connected without a wire, is it possible in a brief future?
  48. A

    Electricity and Magnetism Electric Field Problem

    1. Problem Statement: Find positions on the x-axis for the charges Q1 = -1 C and Q2 = +3 C so that the electric field is zero at x = 0. Homework Equations :[/B] I'm thinking I need to use Coulomb's law for this one. I'm just having trouble figuring out where to start. Coulomb's states E=kQ/r^2...
  49. Y

    Why does Fleming's right hand rule apply for induced current

    I know that the right hand rule applies for induced currents, and the left hand rule is for motors, but why? It doesn't seem to connect with any other physics laws and is very counter-intuitive that the current will flow in one direction rather than the opposite direction if both are...
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