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.

View More On Wikipedia.org
Recent contents Top users
  1. L

    How do electrolytes conduct electricity without redox?

    Say you have salt water. If you apply an voltage between two electrodes Na+ ions will drift towards the negative electrode and Cl- ions towards the positive electrode. If a redox reaction happens at the electrodes, the ions transfer electrons to the electrodes and current continues to flow until...
  2. S

    Why Am I Getting Electrical Shocks from Water and Water Pipes?

    Hello everyone... Help me out.. I installed a geyser 3 weeks back which has a rating of 15A and I connected it to a 32A MCB. This is connected to a 16A separate MCB in the main board. Whenever I turn on the geyser, it works for some 10mins and then turns off without water getting heated. I...
  3. A

    Where is North, given this current?

    Homework Statement Copy the diagrams in Figure 7 into your notebook, and draw the direction of the conventional current or the magnetic field lines. Also indicate the location of the north and south poles where appropriate. FIGURE 1 FIGURE 2 Homework EquationsThe Attempt at a Solution Using...
  4. N

    Electricity transmission explained?

    I'm working an electricity broking desk at a finance firm this summer, and was hoping someone could clarify the science of it all for me. -For example, a plant has 350MW of capacity. Say 350MWh are demanded for a one hour period. Assuming this plant bids successfully to supply the full amount...
  5. F

    Exploring the Basics of Electricity for High School Students

    Hi guys, Basically I'm studying electricity at high school level and I need recommendation on a decent book that covers the basics on electricity as the official textbook misses a lot of detail and there's limited practice questions. I've been to several libraries but the books I've found, most...
  6. Hijaz Aslam

    Discharging a charged capacitor to another neutral capacitor

    Homework Statement After a capacitor of capacitance ##C_1## is charged up to a voltage ##V_o##, the Battery is removed from the circuit. Another capacitor of capacitance ##C_2## is connected in series with the capaciotr ##C_1##. Find the charge on each capacitor after equilibrium is attained...
  7. W

    Engineering Tough Circuit Problem, Find Current When Switch is Closed

    Homework Statement I got questions a) and b), but I'm stuck at c) and d). Homework Equations Kirchhoff's Loop and Junction rules. Equivalent resistance in series: Req = R1 + R2 Equivalent resistance in parallel: Req = ((R1)-1 + (R2)-1)-1 The Attempt at a Solution I really haven't gotten...
  8. Hijaz Aslam

    Gauss Law of Cube in non-uniform linear Electric Field.

    Gauss's Law states that if a Gaussian Surface encloses a charge ##q_{enc}## then the electric flux through the Gaussian Surface is given by ##\phi=q_{enc}/\varepsilon_{o}## . It also states that any external field does not contribute to the Electric Flux through the Gaussian Surface. I am bit...
  9. J

    A small doubt about electric flux

    Hey there... As far as I know, electric flux is a scalar quantity which means that negative values are smaller than zero. This concept really confuses me since most of the exercises I dealt with suggest that negative flux somehow is larger than zero flux Example 1 the uniform field is directed...
  10. R

    Does experiencing a static shock mean that you are grounded?

    If I built up static in me and then touch a doorknob and get shocked, am I then sufficiently grounded to be able to touch electrical components? Or was it just that the extra electrons were discharged and I should still ground myself in another way before touching electrical components?
  11. C

    What is the correct way to analyze a circuit with resistors?

    Homework Statement [/B] R1 = 42 Ω R2 = 124 Ω R3 = 119 Ω R4 = 105 Ω Rx = ? I4 = O A Homework Equations R = IV V = V1 = V2 for parallel Resistors Iequiv = I1 +I2 for parallel Resistors Vequiv = V1+V2 for series Resistors Iequiv = I1= I2 for series Resistors The Attempt at a Solution I have...
  12. G

    Engineering Simple Circuits: Understanding Node Voltage Analysis

    Homework Statement Homework Equations ##v1 + v2 + v3 = 0## (KCL) The Attempt at a Solution I don't understand why my solution is wrong. I was taught that if I were to use Node Voltage analysis, I should put nodes with voltage sources into supernodes which was what I did, however, my...
  13. S

    Why do we need two wires for electricity?

    I know the circuit must be complete in order for devices to work. I want to understand this with an analogy in reference of a battery. Let there be a bulb in the circuit connected to a battery. Now if circuit is closed then what happens in the circuit? Electrical energy lights up the bulb so is...
  14. ryanuser

    Scintillator to generate electricity?

    Hi, I am doing a high school project based on physics and I wondered if my idea works or not. So I was thinking to use gamma rays as a source of energy to produce enough current to charge my phone. My question is that would it be possible to use scintillators (used in photomultipliers in...
  15. E

    Electric Potential with Non-conducting sphere and conducting shell

    Homework Statement A spherical nonconductor of radius a carries charge +Q uniformly spread through its volume. 2 hemispherical conducting shells of inner radius b and outer radius c are placed concentrically with the nonconducting sphere to form a single conducting sphere. The conducting shell...
  16. J

    Where does electricity go after ground?

    Hello, I am sure that this question has been answered on here before, but i could not find it. Why is the Earth ground, and where does the electricity go after it gets there. I understand that ground is potentially lower than that of the power company's production etc. but i am curious as...
  17. C

    Can a 2 KW Motor Efficiently Power a 50 KW Generator?

    hello to everyone, first of all I apologies for my bad english the idea is - i will use 2 KW motor to spin a 50 KW alternator or generator. the cost to buy electricity is 17 p/kWh and to sell it to the grid is 5.1 p/kWh so my motor will use 48 kW in 24h with a cost of 8.16 pounds in 24 hours...
  18. C

    Power wasted/delivered to a resistor

    Homework Statement two 8 ohm resistors and a battery of emf 12.0V and internal resistance of 8ohms are connected in series. Calculate the power delivered to each external resistor and then calculate the power wasted due to internal resistance. I keep coming up with the answer 18 but apparently...
  19. S

    Calculate Potential Energy of Electron at a Parallel Plate Capacitor

    Homework Statement An electron with a speed of 5.0x10^6 m/s is injected into a parallel plate apparatus, in a vacuum, through a hole in the positive plate. The electron collides with the negative plate at 1.0x10^6 m/s. What is the potential difference between the plates? Vi= 5.0x10^6...
  20. Hijaz Aslam

    Electric Field of a circular arc at a point

    Homework Statement Given that the circular arc wire with radius 'r' has a linear charge density ##\lambda##. What is the Electric field at the origin? Homework Equations ##\vec{E}=\frac{kq}{r^2}## where ##k=9\times10^9## is a constant. 3. The Attempt at a Solution I took a small segment dy...
  21. J

    Help with electric field problem- Yr 12 physics

    Homework Statement Protons are accelerated by an electric field passing through a hole in the anode and accelerated towards the cathode (to the right) A proton passes through the anode at 6.2 × 105 m s–1, and passes through the cathode at 8.8 × 105 m s–1. Show that the strength of the electric...
  22. E

    Heat pump electricity production

    Greetings. I just want to understand heat pumps. As far as I know - they keep a house warmer than it could be using a regular electric radiator, using the same amount of energy. I am wondering - if a heat pump outputs, say, 3 kW of heat energy from 1 kW of input electric energy from the grid (or...
  23. D

    Why are there only 3-phase and 1-phase systems in electricity?

    Homework Statement why are there only 3 phase systems and 1 phase system, not other systems like 4 phase or more? why do electricity only use 50/60 Hz? Homework EquationsThe Attempt at a Solution for number 1 i assume if there are more phase, the price will be higher so it won't be used. But i...
  24. 2

    [Electricity & Magnetism] Finding the voltage of a battery.

    Homework Statement Hello. I just need someone to check if I'm approaching the problem correctly (the steps I've taken are given below). I drew a quick sketch of the circuit here: http://i.imgur.com/mClttXn.png?1 In the problem, I am given the capacitances of A, B, and C. I am also given the...
  25. M

    Electricity and Magnetism Project

    Hello everyone. For this semester's laboratory, we are required to work on a project on the topic of E&M (preferably). They've given us freedom of choice as to what we want to work on and I was wondering if any of you guys know some interesting and cool topic we (me and my partner) can study...
  26. G

    Greetings from a 70 year old generalist

    Many folk like to use the phrase "talking truth to power", but those of us who do have colorful work histories. My life has been in technical fields, both in the Air Force and industry. Now retired, I earned a Master of Science in Energy and the Environment, was a Senior Engineer for a large...
  27. O

    Angle of Deflection of water in an electric field

    Homework Statement I'm in the middle of a Year 11 open physics practical, and my partner and I have decided to attempt to find the angle of deflection of a stream of water when an electric field is placed near it. In order to do this experiment, we have a lot of 9V batteries, a voltmeter, a...
  28. B

    Point charge or distributions?

    Do charges exist as a point or a distribution? Or does it depend on the situation? Or does the concept of image mean that it's very difficult to tell, and if so why is the point charge model being pushed so hard, what phenomena does it explain that distributions cant?
  29. Alxb577

    Electromagnetics Essay Topic Ideas

    Hi Everyone, I need to write an essay for my electromagnetism class and i was wondering if anyone has good topic ideas. My criteria is that it needs to be 10 pages and I would like something that is interesting for me to research and write about. I was thinking so far of magnetic levitation...
  30. B

    Electricity Question Amps & volts confusion

    Homework Statement [/B] A) If a laptop computer charger is designed for use in a country where mains voltage is 230V. Will the user still be able to charge the laptop computer in a country where the mains supply is 110V? B) Also what happens if a 110V charger is used in a country where the...
  31. F

    Calculate average current flow in an electric eel (Simple Circuit Questions)

    Homework Statement i) A particular source of potential difference is capable of providing a maximum potential difference of 2 Volts. Sketch how you would connect two such sources to provide a potential difference of 4 Volts. ii) If each source can provide a current of 20 mA before its...
  32. Steven Ellet

    Can a Klein Tools Non-Contact Voltage Tester Measure Static Electricity?

    Would a Klein Tools Non-Contact Voltage Tester or similar be able to measure static electricity? If not what will? https://www.google.com/search?q=how...hop&q=Klein Tools Non-Contact Voltage Tester
  33. E

    Electricity and Magnetism Workbook

    Hello everyone. I am searching for a book full of practice problems in Electricity and Magnetism and was hoping someone could recommend some. I have been searching on my own, but could not find any. I have a classmate who has one from china, where it is pure questions relating to the subject and...
  34. G

    Finding Unknown Currents in a Two-battery Complex Circuit

    Homework Statement Look at the circuit given in figure 1. Solve for the three currents, I1,I2,I3. Homework Equations KVL: Sum of voltages in a closed loop equals zero KCL: Sum of currents entering a junction equals the sum of currents exiting a junction Ohm's Law: V=IR NOTE: Nodal analysis...
  35. adjacent

    Definition of Electro Motive Force

    Homework Statement The title. I am confused with the definition as my textbook does not have a good definition for this. P.S I have my exams tomorrow so I can't ask my teacher now.(Mid night) Homework Equations $$V=\frac{E}{Q}$$The Attempt at a Solution E.M.F is the energy given to each...
  36. B

    Simple divergence theorem questions

    So I understand the divergence theorem for the most part. This is the proof that I'm working with http://www.math.ncku.edu.tw/~rchen/Advanced%20Calculus/divergence%20theorem.pdf For right now I'm just looking at the rectangular model. My understanding is that should we find a proof for this...
  37. davenn

    Can Humor Spark Creativity in Learning About Electricity?

    a good laugh :)
  38. avito009

    How is electricity produced from solar cells?

    Is electricity produced from solar cell because light has electric and magnetic fields?
  39. R

    Convert sunlight to electricity in a given area

    Homework Statement Question: Lake Mead is formed by the Hoover Dam, and while it actually changes in area and volume, consider it has an average area of 100,000 acres. Assume that 250 W/m^2 of sunlight falls on Lake Mead, how much electricity could be produced if this lake area was covered by...
  40. shinnsohai

    Can You Generate Electricity from Saltwater and Which Metals Should You Use?

    There's a confusion before I proceed to the experiment of "Generate electricity out of Salt water" -The variation types of metal that I can choose for replacing "Copper" and "Zinc" from the periodic table. How do I determine which combination will ends up with the maximum efficiency? -How long...
  41. R

    Water bending with static electricity

    thinking about growing cacti in a tropical climate...could i perhaps build a charged scaffold around them to keep most of the rainwater away? if this is possible i might lose the walls i tend to stay in as well by upscaling it.
  42. C

    Car Electricity Questions - Get Answers Now!

    Hello, I have generally questions here, so I hope, that you will help me 1. How can a moving car become positively charged? 2. If I touch the door of a charged car, sometimes I get something like a shock. Why does it happen? I would appreciate it, if you will answer me. Thanks in advance
  43. C

    Diagram to show static electricity

    static electricity diagram Hello! I am new here! I need your help... How would I draw a simple diagram to show how static electricity is made use of in a photocopier to position the black toner where is needed. It sounds a litte bit tricky and I think how it would looks like. Thanks in...
  44. A

    Exploring Static Electricity: The Science Behind Balloon and Paper Interactions

    I was reading that if a balloon is rubbed against cloth, it becomes charged and therefore it sticks to a wall for a short time if I place it against a wall. So how come if I have a non-static charge (current charge) and then I placed small bits of paper besides it, the paper doesn't stick as...
  45. T

    Where and how do I start learning about electricity?

    Hello, thank you for taking the time to read this. I am so uneducated that I do not know how to even begin to explain what I am even uneducated in so, I'll just attempt to explain. I am fascinated with electricity and the endless things we can do with it, I am more specifically interested in...
  46. P

    Pumping water up without electricity

    I'm trying to make a water purification system for use in rural communities. The thing is, most rural areas are off the electricity grid in India, where the system will be implemented. One component of the system needs water to be pumped in from a reservoir below it. The pumping method need not...
  47. S

    Recycle Electricity: Is It a Good Idea to Build a Long-Lasting Device?

    If I can recycle electricity with a device made of pieces of equipment that ware out very slowly (Years or longer) would it be a good idea to build such a device?
  48. D

    In order to generate electricity is copper required?

    Copper conducts electricity and so does other metals like silver. Now a new material is coming to play which is graphene, But I was wondering in order to generate electricity must it be in copper coils? Can it be in silver coils, graphene coils? ^.^
  49. kartikwat

    Conduction of electricity in semiconductors

    When studying about semiconductos what are the valence band and conductivity band .what are its properties,where is it addressed.
  50. N

    Electricity Generation by piezoelectric effect in Injection Moulding

    Hello, Actually i want to make use of Clamping Force of Injection Moulding Toggle System to produce Electricity by making use of Piezoelectric effect. For example, if we place a quartz crystal (or any other piezoelectric material) on either side of the platen, then on each machine cycle, when...
Back
Top