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. U

    How Do You Calculate the Initial Separation Between Two Charged Particles?

    Homework Statement One particle has a mass of 3.00 10-3 kg and a charge of +8.00 µC. A second particle has a mass of 6.00 10-3 kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation between them is 0.100 m...
  2. C

    How to Solve This Complex Current Electricity Circuit Problem?

    Hi friend I am Stuck in a problem. Please help me in solving this. Thank you all in advance. The problem is as follows. https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xpf1/t1.0-9/10270329_1576533655907072_4352617381833809587_n.jpg...
  3. R

    Can Sea Waves Provide a Reliable Source of Electricity Year-Round?

    why can't electricity be generated from sea waves which are available through out the year. What is required for generating electricity is a source of energy that can rotate a turbine, which the sea waves are definitely capable. So what is the hurdles faced in this direction generating...
  4. N

    Which Book Best Explains Electrostatics and Electrodynamics for Beginners?

    Hey PF, I've studied electrostatics and electrodynamics in the past years in high school, but it was just school-study I never had a chance to thoroughly understand them, I'd like to read and learn more about electrostatics and electrodynamics on my holiday, so I'd like anyone to...
  5. T

    Electricity Without the analogies (need expert varification)

    The topic of how electricity actually flows is one of the worst answered most common questions I've seen. Best answer I've seen was here by Gokul43201: https://www.physicsforums.com/showthread.php?t=377359&page=3 I also HATE the "shock-wave" analogy YET I'm still confused, as I know an...
  6. z.js

    Faulty electricity homework question?

    Hi, Hoping someone will be able to help me out with a electricity homework question that sounds a bit unreasonable to me. Homework Statement Question 8 (Read the section after Q4 first!) The I-V characteristics of a diode and a resistor to be used in a simple circuit with a varaible...
  7. C

    Engineers' Views on Storing Solar Energy as Potential Energy

    Store energy from solar panels in form of gravitational potential energy. For example: build a system which will lift a very heavy block. When you need energy, you just get down the block What do engineers think about that?
  8. M

    Can PVC Prevent Static Charge from Grounding in Mylar Setup?

    I am using a negative ion generator module that I purchased to generate a static electric charge in a 4' x 7' aluminized mylar blanket. I made a cage out of 3/4" PVC tubing to hang the mylar from (vertically) - I want to suspend the mylar from the PVC so that the mylar is insulated from any...
  9. adjacent

    Why NaCl does not conduct electricity in solid state?

    Homework Statement The titleHomework Equations NahThe Attempt at a Solution It has no free moving ions or electrons Then, my teacher saw the electrons and gave 0 marks to the question(It was on the test paper) He said that if he didn't see electrons there, he would have given a mark. Why? I...
  10. xunxine

    Does Adding of Change the Meaning in Current of Electricity?

    This is probably a problem with semantics. The textbook that I'm using has the title "Current Electricity". The corresponding syllabus has the title as "Current of Electricity". Is there a difference between the two titles? Would "of" in the middle make a difference or used in another...
  11. J

    Superconductors and Space: Can Electricity Bend Reality?

    Hi! I was wondering that if you could put enough electricity into a superconducting coil if it would be powerful enough to bend space?
  12. B

    How far would physics have progressed without electricity

    How far could the study of physics have advanced without the discovery/invention of electricity and electrical power? Or in other words, what fields and major breakthroughs could not have been achieved without the availability or knowledge of manipulation of electricity?
  13. A

    Trapping light without electricity

    Hello all, I would like to know a method to trap light. That is, it should be pretty simple and non-electric. It doesn't need to trap all light, just part of it at the least. It should also be able to give out light by itself if certain conditions are met (which conditions do not really matter...
  14. J

    Electricity in a Vacuum: Investigating 1e9 Voltage

    Good day. What happens if a vacuum to put two electrodes, 1 cm apart, and electrical voltage in 1e9? Thank you.
  15. Steven Ellet

    Can Static Electricity be Measured and How Dangerous Can it Be?

    How do I measure static electricity or is it even possible?
  16. F

    Equal and opposite forces with electricity

    I have a question concerning the generation of electricity and equal and opposite forces. I've been having a hard time describing it. Sorry if I don't get my point across. If I start off with using a generator to generate charge in capacitors, I have the equal and opposite forces being the work...
  17. E

    Difficult Introductory Electricity Circuit Problem - Capacitors

    Difficult Introductory Electricity Circuit Problem -- Capacitors Homework Statement The Attempt at a Solution This problem was very difficult, and the most I could do was re-arrange the circuit into a make-shift Wheatstone bridge with all capacitors instead of resistors/voltmeter...
  18. F

    A question of electricity regarding emf and voltage

    Homework Statement A relay is required to operate 800m from its power supply, The power supply has negligible internal resistance. The relay requires 16V and a current of 0.60A to operate A cable connects the relay to the power supply and two of the wires in the cable are used to supply...
  19. T

    Differentiation with electricity help

    Homework Statement A circuit consists of 230V supply, a switch, a 2mH inductor and a 12k ohm resistor in series When the switch is closed at time t=o, a current i begins to flow in the circuit: The current is modeled by the following equation: i= v/r (1-e^-Rt/L) Determine the...
  20. Manraj singh

    Can a Rotating Fan Be Used to Power a House?

    Other people must have come up with this before, but what if we attach a lever to a rotating fan. The lever can be attached to a bulb to run it, or maybe something like a Leyden jar or a KERS, (mind me if its the wrong device, i am just a rookie) to store it. So won't the house be self sufficient?
  21. R

    Can a Charged Particle Move in a Straight Line in a Nonzero Magnetic Field?

    Homework Statement A charged particle moves in a straight line through a particular region of space. Could there be a nonzero magnetic field in this region? In either case, include a sketch as well as prose in your justification. Homework Equations The Attempt at a Solution The...
  22. S

    Intermediate Mechanics and Intermediate Electricity & Magnetism

    So I took honors level introductory physics courses my first year. Here are the descriptions. I did worse in the second course than the first. This coming year I will be taking intermediate level courses for these topics. The difference is that I will have both Intermediate Mechanics I and...
  23. O

    Current from static electricity

    If I rub my socks around on the carpet, then touch the end of my unplugged laptop charger, and get a spark, why doesn't the breaker pop?
  24. Gamma

    Electricity Safety: AC & DC Current Limits for Intro Physics Labs

    I would like to ask the experienced experts about the safe limits for AC and DC currents to be used in intro physics labs. People say DC is dangerous because one can’t let go of the wire if the wire was carrying certain DC current. Following link has a chart with current limits for AC and DC...
  25. T

    Static Electricity vs Current in a Closed Circuit

    Hi, I'm an automotive technician. I have trouble understanding a couple basic electrical concepts. The problem is that I am more or less taught that current flows through CIRCUITs. When analyzing electrical problems, I think current will only flow if there is a voltage (potential...
  26. C

    Help with electricity, four wires that carry current

    Homework Statement So four wires are arranged in a square and all carry the same current "I" They are all the same distance apart. The two on the left are coming out towards you "O" and the two on the right go away from you "X" I knew I would need kI^{2} divided by distance, but I"m not...
  27. P

    Electricity and Air: A Fascinating Interaction

    A bird perches on a bare high power line and nothing happens to it. A man standing on the ground touches the same line and gets a fatal shock. This is supposed to be because there is potential difference between the ground and the line which the man touches but similarly, isn't there also a...
  28. Astronomy

    Electricity Formula: Difference between E=σ/2ε0 and E=σ/ε0

    Hi I want to know what is the diffrences between E=σ/2ε0 & E=σ/ε0 of course I know we use the first for a very huge page but what about the second formula? I saw in some solving of question when we have 2 pages infront of each others we use both of them... I want to understand the deep...
  29. C

    Design lift without electricity

    This is my project..you have any idea how can generate power to lift elevator.
  30. B

    How is magnetism generated around an electron?

    how can magnetism be derived from electricity at the sub atomic level?? how is the magnetic field generated around an electron? if magnetism is just generated due to angular momentum of the electron it is said that if calculated the spin of electron would exceed light speed ; so will it work...
  31. P

    Static Electricity: Charging by Friction: Understanding MIT demo

    MIT has a Physics Demo called "Rubber and Glass Rods with Tinsel and Balloon" (Not sure if I can post links but easily found on youtube). I have watched the video several times but am a bit puzzled. First the lab technician charges the rod by friction but then when he moves it close to the...
  32. M

    Understanding Voltmeter Sensitivity and Load Effects in Electrical Circuits

    Hi. I have a problem understanding a question for my electronic engineering course. We have a subject that's directly translated to 'the knowledge of electricity and measurement techniques'. I do hope this is the correct forum to ask for help at. Homework Statement Given the...
  33. J

    Measuring electricity passed to ground from an antenna

    First of all, excuse me if this question is too basic: I feel like it shouldn't be a struggle to understand, but the fact is it is. We put up an antenna to play with radio a little, and someone we were working with showed us that there's a reading on the voltmeter without any of the equipment...
  34. N

    Static Electricity and Number of Electrons

    Homework Statement When you rub a gold sphere with rabbit's fur, the gold takes on a negative charge (and the rabbit fur positive). Suppose the gold sphere has a mass of 190.0 g and it obtains a net charge of 0.540 μC. Calculate the ratio of the number of electrons added to the gold sphere to...
  35. E

    Generation of Static Electricity

    I was wondering if and/or how one would could calculate the the generation of static electricity between 2 materials. For example material A is immersed in substance B and moves within it at a constant velocity. Knowing the velocity and volume / surface area of material A and the electron...
  36. B

    How to safely create static electricity from AC current

    Is there a simple way to "make" static electricity from an AC outlet? Looking for a way to make my hair stand (what is left of it) on its end for an experiment. Thanks for your comments in advance.
  37. W

    Introduction to Electricity: Basic AC/DC, Resistors, Capacitors, and More

    Hello, I am looking for a basic introductory textbook on electronics. Since it's introductory, nothing too rigorous required. Topics: Basic AC/DC introduction Current, Charge, Voltage Resistors Series/Parallel circuits Ohm's Law Capacitors Semiconductor devices (diodes, doping...
  38. B

    How can you use electricity to create static charge and bend water?

    Hello all, I watched a youtube video where you can rub a plastic tube on your hair, and the static electricity generated will pull a stream of water falling from a faucet. My question is, how would this be possible to do electrically? Meaning, using electricity or a battery powered...
  39. M

    Static electricity and circuit breakers

    Hi I have seen electric technicians while racking out high tension circuit breakers, use a wire that has one end grounded and they use the other end to touch the bus bars on the breaker in case of a static charger, they carry out this procedure before they do any work on the CB in case they...
  40. D

    A simple question about the flow of the electricity

    Hey guys! I'm trying to get a bettter undesrstanding of how the electric circuits work. But I do have a rather simple question. So, in the internal circuit we give energy to the charge. Let's say that I have an electricity source and two resitors, like this: So when passing through circuit...
  41. hideelo

    Relationship between electricity, magnetism, and relativity

    I know that magnetism can be explained as the relativistic interaction between say a current, and a moving charge. My question however is twofold, is magnetism nothing but electric forces when relativity is taken into account? If the answer is yes, does that make magnetism a sort of psuedo-force?
  42. bcrowell

    Free edition of Purcell, Electricity and Magnetism

    Thirty years after learning E&M from the wonderful book by Purcell, I noticed that the copyright page of my dog-eared copy of the 1965 edition includes a notice stating that it is available for use by authors and publishers on a royalty-free basis after 1970. The book has gone through two more...
  43. K

    How Is Electricity and Magnetism Used In Computer Science?

    I am a computer science major and we are required to take two semesters of physics. First semester is based on mechanics and the second semester is focused on electricity and magnetism. I was wondering how these topics are used in computer science and in what specific area? I have tried looking...
  44. S

    Electricity from a kerosene/gas mantle?

    Like the title says I was wondering if it would be possible to generate a couple of watts of electricity from a kerosene or gas mantle. Less than 0.5% of the energy in the fuel is being converted to light which means that in the 33kJ per mL of kerosene nearly 9 watts is being lost as heat...
  45. M

    Aircraft Certification (Static Electricity Dischargers)

    The little wicks placed at the wingtips to get rid of static electricity on the wings and body of the aircraft are vital to aircraft. I am interested in what the certification requirements for placing these ont he wings. I assue the formula of would include things like 1-surface area 2-speed...
  46. B

    Wireless Electricity: Magnetic Resonance vs. Magnetic Induction

    What is the difference between magnetic resonance and magnetic induction when it comes to charging devices and other types of wireless electricity. I was doing some research on this but was not able to find a clear answer. If someone could help me with this that would be greatly appreciated...
  47. F

    Why do some electricity pylons collapse in extreme temperatures ?

    Homework Statement Using physics knowlege, why do some electricity pylons collapse in extreme temperatures. Homework Equations The Attempt at a Solution Don't know the physics formulas or equations that could be used. High winds would force the pylons to collapse as the structure hasn't been...
  48. G

    Static electricity - Quantity of charge induced.

    Hi all, Let us say I have rubbed cat fur with nylon. Is there any relation for determining the amount of charge (in Coulombs) induced on either of the materials? Thanks in advance.
  49. D

    Does Work Done by a Spherical Force Field Depend on Path?

    Homework Statement A force eld E has the spherical components Er = (2Dcosθ)/r3 Eθ = (Dsinθ)/r3 E\phi = 0: (a) Evaluate by line integration the work it does in taking a point (parti- cle) from point A in the diagram to point B via the quarter circle r = a; 0 <...
  50. D

    Converting everyday heat energy into electricity

    Separate question. Can anyone tell me what the limitations would be of trying to convert the planet's ever increasing heat into electricity. I'm imagining building materials that could take 100-120 degree heat and convert it for use in running home appliances, including air conditioners. How...
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