What is Electricity: Definition and 999 Discussions

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. F

    Is Ambient Static Electricity Always Present in Our Surroundings?

    I think I remember reading somewhere that almost every moment of our lives we are surrounded by thousands of volts of ambient static electricity caused by the movement of air and clouds, it's just that we don't notice it. I may have mixed up my information so I'm just asking for clarification...
  2. D

    Electricity physics homework

    Homework Statement A 19-cm-long nichrome wire is connected across the terminals of a 1.8 V battery. If the current in the wire is 2.1 A, what is the wire's diameter in mm? Homework Equations R = Rho*L -------- A v=ir The Attempt at a Solution rho for this = 100...
  3. T

    Can Static Electricity be Converted into Continuous and Useful Levels of Power?

    http://www.nuenergy.org/pdf/static-electricity-converter.pdf
  4. N

    Charged Rod and Neutral Sphere Interaction: Repulsion Confirmed?

    You have a positively charged rod and you have a neutral metal sphere hanging on a wire. If the positively charged rod approaches the sphere, the sphere will be repulsed - correct?
  5. E

    How Does a Hairdryer Use Less Current Despite High Home Voltage?

    Hi, The UK., electricity supply is 13 amps at 230 volts. With such a current and e.m.f., how can we run appliances which don't need that e.g., a hairdryer with a 3 amp fuse. What stops the full 13 amps overwhelming the appliance? My question is not well put but I'm sure you know what I'm...
  6. M

    Flow of electricity: Open versus Closed Circuit

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  7. P

    Explaining the static electricity

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  8. A

    Current electricity and circuits

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  9. A

    Archived Simple question on current electricity

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  10. M

    Flow of electricity and resistivity (ohms law)

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  11. GRB 080319B

    Distribution of charge wrt static electricity

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  12. T

    Converting Waste Heat to Electricity: An Assignment Exploration

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  13. Z

    Current Electricity Homework: Rnet~l2/A & Variables

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  14. I

    Which term, electricity or electron, was coined first?

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  15. S

    Understanding Relative Electricity: An Electron's Perspective

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  16. Drakkith

    Converting Ions into Electricity

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  17. I

    What are the average global prices for electricity per 1 kW-h?

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  18. A

    Engineering Electricity - Solving unknown variables for mixed circuits

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  19. N

    Three charges in a plane- static and current electricity

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  20. M

    Electricity Confusion: True or False?

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  21. S

    Transfering Electricity w/o Medium? (Electron Beams?)

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  22. N

    Static and current electricity

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  23. M

    Exploring Electricity Generation From Turnstile Gears

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  24. A

    Is E&M a Significant Part of a MechE Degree?

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  25. N

    How Does the Resistance of a Light Bulb Change When It's On Versus Off?

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  26. R

    Wireless Electricity: Replicating MIT's Witricity on Smaller Scale

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  27. B

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  28. B

    Physics Grade 12 HELP Electricity Unit

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  29. G

    Wireless transmission of electricity?

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  30. S

    Problems about Electricity and Magnetism

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  31. I

    Generating electricity from electric charge?

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  32. Q

    Can Electricity Flow Without a Complete Circuit?

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  33. C

    Electricity & Magnetism: Potential Field

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  34. T

    Buoyancy impulse turbine. Perpetual electricity. Is this possible?

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  35. T

    Static Electricity Effects on Charged Objects

    Homework Statement How would static electricity on your clothes or on your body affect an experiment involving charged objects? Homework Equations Coulomb's Law The Attempt at a Solution The static electricity would attract the objects due to the like charges, assuming the objects...
  36. J

    Static electricity in outer space?

    Static electricity in outer space? Somewhere I read that a space vehicle traveling in outer space picks up a static electricity charge. Is this true and if it is true, where does that static electric charge come from?
  37. B

    Wind Farms: Are they Really Providing Useful Electricity?

    I came across a report entitled "Wind Farms Provide Negligible Useful Electricity" by Richard Courtney. You can google it its just available free on the internet. What I wanted to know, if anyone here works in the power grid industry, was it true or should it be taken with a pinch of salt...
  38. S

    Heating a block of Rubber by passing electricity

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  39. C

    Use vibration to generate electricity

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  40. I

    How Long Can a Toaster Run on 6 D Cell Batteries?

    Homework Statement A toaster, which uses 6 alkaline D batteries, must produce at least 900 W of thermal energy. D cell batteries have a capacity of about 5 Ah. How long can the batteries run the toaster? Homework Equations The Attempt at a Solution Well I know that Power is (J/s)...
  41. S

    How crystal + electricity works together

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  42. C

    Electricity and Magnetism Question

    Homework Statement The potential caused by an array of charges in a region of space can be described by the equation V(x,y,z)=2x+xy+y2-xz2 volts, where all distances are measured in metres. If a charge of 2 mC is moved from the position r1=(1,2,0)m to r2=(3,1,0), calculate the resulting change...
  43. T

    Using magnets to generate electricity(?)

    Hi, Recently I've become interested in the possibility of using magnets to generate electricity, a "magnet motor" if you will. There are evidence of a lot of different attempts on the internet as well as a number of actual patents for these motors. When I say "magnet motor" I mean a...
  44. J

    Understanding the Variation in Electricity Rates in England

    If my memory serves me right I recall once someone said something like that in England or the UK electricity rates varies during 24-hour period. It costs more during nighttime than during daytime. Is this true? What is the rationale behind this? Please let me know. Thanks.
  45. E

    What Gauge Wire Should I Use for a 1000ft+ Electricity Run to a Barn?

    Hello, my name is Kevin and I going to be adding electricity to a barn about 1000ft away from my house. The barn will act as a second home and will need to be using around 2-10KWh. I figure it will never exceed 10KW per hour. I will be running it underground in heavy duty poly casing. My...
  46. L

    Physics-current electricity, circuit

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  47. E

    Electricity generator theory question

    What are the factors that influence a generators output (efficiency?). Does the rotational speed of the magnets influence output? If so, by what magnitude can this be increased? ie. If a system is running at x rpm by what relation can the output be increased if the rotational speed is through...
  48. G

    Help diagnosing 'static electricity' problem

    From the attached photograph I have a continuing problem with what I would describe as “static electricity”. Shocks are being received from the rail system and also the aluminimum framing supporting the electrically operated window shutters. As indicated, the deck is a proprietary plastic...
  49. Q

    Sea is a good conductor of electricity

    hi , i was just wondering, if the sea is a good conductor of electricity, when thunder should strike it, won't electricity be conducted everywhere and everything dies in the sea? how far does electricity spread out? is there some sort of limiting factor? thanks!
  50. I

    Purcell - Electricity and Magnetism

    Does anyone know where I can purchase the hardcover 1985 Electricity and Magnetism? Some schools, such as Caltech and MIT, still use the book; however, Caltech does not have it in their online bookstore and MIT lists an 09 edition (which I assume is an ebook?). Some copies are floating...
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