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. A

    Converting a laser beam to electricity with photovoltaic cells

    Hi, I'm new to this forum so please don't get mad if this post is in the wrong place. I have a laser beam pointed at a solar panel (regular PV cells) and the current comes out as expected on my oscilloscope (small waves varying like pulses between 0.45 and 0.50 V regularly). I tried...
  2. C

    Calculating Energy Use and Wind Turbine Requirements for High-Speed Trains

    Hi I’m trying to estimate how much electricity a new high speed train in the UK would use to go at 400 km/h and how many wind turbines it would require to run it. My physics is a bit rusty so I’d appreciate it if someone would check my calculations. It is difficult to estimate how much...
  3. A

    Electricity and Magnetism homework

    Homework Statement What is the Kinetic Energy of an electron that passes undeviated through perpendicular electric and magnetic fields if E = 4.0 kV/m and B = 8.0 mT? m_{e} = 9.1 \times 10^{-31} \textup{kg} q_{e} = 1.6 \times 10^{-19} \textup{C} Homework Equations I got stuck doing...
  4. B

    Does electricity have momentum?

    w = x = y = z , If this were a pump system with water, I think the pressure and flow would be much higher at reading #2, because water has momentum? What about electricity, would the current be higher at #2?
  5. Femme_physics

    Electricity basis resistors/power/current question

    Homework Statement A voltage of a car battery is 12V, the current requires for movement is 200A. When we turn the lights on the voltage drops to 11.1V. The power of each backlight is 55 watt, the power of each front light is 12 watt. A) Calculate the internal resistance of the battery...
  6. F

    Concept of Field Lines, how Electricity vs Gravity

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  7. L

    Question about the concept of electricity in solar cells.

    Ok so I understand how a voltage source works, with electrons flowing from a high potential to a low potential. But I'm a little confused about solar cells. So the way they work is that an incoming photon strikes an electron and gives it enough energy to break free and create a current. But...
  8. Femme_physics

    Electricity: Calculating power/energy/energy conversion efficency

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  9. P

    Conceptual understanding of generating electricity

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  10. L

    Nikola Tesla's Observation of Vacuum Electricity

    Nikola Tesla observed that electrons transmitted through a near perfect vacuum in his vacuum tubes appeared as corona several feet through the air surrounding the tube. He thought that if there is nothing in the tube between the electrode and the glass then how do the electrons convey through...
  11. T

    Understanding the Nature of Electricity: Flow of Electrons or Electric Charge?

    I've always been given conflicting messages like that we only use conventional current because they were confused years and years ago. Anyway I'm wondering if 'electricity' is the flow of electrons or "electric charge" like I heard once, I assume they meant like a flow of empty valency shell...
  12. 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...
  13. D

    What Is the Diameter of a Nichrome Wire in a Circuit?

    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...
  14. T

    Can Static Electricity Provide Continuous Useful Power?

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

    Charged Rod and Neutral Sphere Interaction: Repulsion Confirmed?

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  16. E

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

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  17. M

    Flow of electricity: Open versus Closed Circuit

    I need help understanding this conceptually, so can anybody please correct me and help me understand this? If I'm correct then just say so.Diagram: http://i324.photobucket.com/albums/k327/ProtoGirlEXE/labVpic3.jpg the circles are bulbsOk so the basically in an open circuit there is no flow and...
  18. P

    Explaining the static electricity

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  19. A

    Current electricity and circuits

    Current electricity... Homework Statement In the circuit shown(please refer to attchment) only thing missing is that the battery has an internal resistance of r. Now When key K1 is closed the ammeter reads I0 whether K2 is open or closed. But when K1 is open the ammter reads I0 /2 when K2 is...
  20. A

    Archived Simple question on current electricity

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  21. M

    Flow of electricity and resistivity (ohms law)

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  22. GRB 080319B

    Distribution of charge wrt static electricity

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  23. T

    Converting Waste Heat to Electricity: An Assignment Exploration

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  24. Z

    Current Electricity Homework: Rnet~l2/A & Variables

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  25. I

    Which term, electricity or electron, was coined first?

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  26. S

    Understanding Relative Electricity: An Electron's Perspective

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  27. Drakkith

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  28. I

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

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  29. A

    Engineering Electricity - Solving unknown variables for mixed circuits

    Homework Statement 7. Find V1, V2, V3, I0, I1, I2, and I3 for the circuit in Figure 2. V0 = 120V R3=15 ohms R1=3 ohms R2 = 6 ohmsHomework Equations Kirchoff's law Ohm's law The Attempt at a SolutionR0 = R1 + R3 = 3 + 15 =18 ohms...
  30. N

    Three charges in a plane- static and current electricity

    Homework Statement An equilateral triangle has sides of 0.11 m. Charges of -8.6, +8.0, and +1.5 µC are located at the corners of the triangle. Find the magnitude of the net electrostatic force exerted on the 1.5-µC charge. Homework Equations kqQ/d^2 The Attempt at a Solution first...
  31. M

    Electricity Confusion: True or False?

    PLEASE help me by telling me if the following is true (below, when I say going with the flow I mean following the direction of electric field, and when I saw going against flow I mean going in opposite direction of electric field) Positive charges go with the flow Negative charges go against...
  32. S

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

    Can electricity be transmitted using Concentrated beams without using wires with no energy lost in the process?
  33. N

    What Is the Potential Difference Across Three Series Resistors?

    Homework Statement Three resistors, 21, 43, and 73 , are connected in series, and a 0.55 A current passes through them. What is (a) the equivalent resistance and (b) the potential difference across the three resistors? Homework Equations i tried to use EPE/q by putting the equivalent...
  34. M

    Exploring Electricity Generation From Turnstile Gears

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  35. A

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

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  36. N

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

    Homework Statement we wish to measure the resistance of a lit light bulb. Unfortunately, the resistance of the light bulb when hot is not the same as when it is cold. when the light bulb is turned on it becomes hot. we cannot easily measure the resistance of the light bulb when it is on (hot)...
  37. R

    Wireless Electricity: Replicating MIT's Witricity on Smaller Scale

    I'm trying to replicate MIT's "Witricity", but on a smaller scale. I have a coil connected to a function generator and then a second coil (with more loops than the first) connected to an LED. So I guess now I have a transformer. And the LED lights up when the coils are up to 10cm apart. I...
  38. B

    Physics Grade 12 Electricity (WHAT DID I DO WRONG)

    Homework Statement Constants Given Colombs constant = 9 x 10^9 Charge of Proton = 1.6 x10^-19 Proton rest mass=1.673 x 10-27 Charge of electron = -1.6 x 10^-19 Electron Rest Mass = 9.11 x 10^-31 kg Homework Equations On the attachement The Attempt at a Solution On the...
  39. B

    Physics Grade 12 HELP Electricity Unit

    Physics Grade 12 HELP! Electricity Unit I have attached the question paper with this post Homework Statement v=2 x 10 ^ 5 m/s Volatage=250 or 500? Constants Given: Coulombs constant = 9 x 10^9 Charge of proton/electron = 1.6 x 10^-19/-1.6 x 10^-19 Proton rest mass 1.673 x 10^-27 kg...
  40. G

    Wireless transmission of electricity?

    Is it physically conceivable the possibility of transmitting electricity between spatially separated objects (e.g. a few meters) in a wireless way?
  41. S

    Problems about Electricity and Magnetism

    I apologize, I wrote all of this out in a word processor before attempting to post it and I did not notice that there is a template for giving problems. I hope you forgive me, my posts tend to be wordy and take awhile to write; attempting to write it in the text box would result in the server...
  42. I

    Generating electricity from electric charge?

    If I have a really big charged object, is it possible to direct the charges to an object/the same place and generate current/electricity from it? It was just something I thought of, totally random, but I'd like to know the reasoning behind it C:
  43. Q

    Can Electricity Flow Without a Complete Circuit?

    i was pondering over a few questions 1) if i were to connect a wire from the positive of a power source, and touch the other end to myself, would i get electrocuted? common sense tells me i will, but where is the close circuit? does electricity flow from source to me to the earth? and then...
  44. C

    Electricity & Magnetism: Potential Field

    Homework Statement The lines show the equipotential contours in the plane of three point charges, Q1, Q2, and Q3. The values of the potentials are in kV as indicated for the +5, 0, and -5 kV contours. The positions of the charges are indicated by the dots...
  45. T

    Buoyancy impulse turbine. Perpetual electricity. Is this possible?

    Although I'm sure people have been looking to develop a solution like this since the beginning of time (at least, the first use of electricity), I'm trying to achieve a design that will enable perpetual electricity generation without the addition of conventional energy inputs. Essentially, I'm...
  46. 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...
  47. 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?
  48. 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...
  49. S

    Heating a block of Rubber by passing electricity

    Hi everyone. I want to heat a piece of Rubber by embedding copper strips or wires in it and passing electricity(120V - 2.5Amp) through it. The room temperature is 0(zero) deg Celsius and i want to heat the aluminum block(5" x 5" x 1") to 10 deg Celsius(Not more than 10 deg). Question...
  50. C

    Use vibration to generate electricity

    Hello, I am a student making a generator. the main idea is to use the vibration with the magnet coil setting with the spring to generate electricity. I will use the permanent magnet, but i know that e = N w B A i decided to have a 12Volt output, constant vibration frequency in 100Hz the A...
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