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.
Homework Statement
2 parallel long, straight conductors lie on a smooth plane surface. 2 other parallel conductors rest on them at right angles so as to form a square of side 'a' initially. A uniform magnetic field B exists at right angles to the plane containing the conductors. Now they start...
This is my first post, and hopefully it's in the right section (my apologies if not!)...I have posted this on Answers, but there weren't any helpful responses there, so I though this might be a better crowd to ask.
Ok, we were taught in our science (electricity) class that in order to reduce...
When current (DC) passed through a wire it creates a magnetic field around it, right? But if you placed magnets around that wire would they interact with the electricity flowing through the wire? If so, to what extent?
Maybe this should be posted in biology but it seems more like an electricity question to me:
I've read that static electricity increases in the cold because of lower relative humidity. This seems to mean that it is more difficult for things to dissipate/ground their electric charge to the...
Building a wind simulator. Control amount of electricity??
I have about 20 6" fans that i'd like to mount to something in which I can control electricity to each fan and essentially simulate wind.
I looked at light DMX controllers for DJ's and that would be perfect except the electricty...
Homework Statement
Suppose electrons are sent through a double slit set up with a the slit width = 5.00nm and d the slit separation = 10.0nm. If the maximum current at the screen is 2.30μA, what is the current at the point .500 cm above the central maximum?
Homework Equations
dsinθ=mλ...
I'm not a physics major or anything (I'm actually a biochem major) but I was just wondering if the universal background radiation that keeps the universe (on average) a few degrees Kelvin warmer than absolute zero could possibly be enough to generate electricity. Essentially this minuscule...
im trying to learn about electricity (especially DC circuits) and having a tough time, the textbook i am using 'fundamentals of physics' by halliday,resnick, and walker doesn't do a very good job of explaining. does anyone know of any good resources that could help?
I'm taking E&M next semester, and the book we use is quite good at explaining concepts, but it only has 9-12 questions per chapter. I would like to do more practice problems. We used the same book for modern mechanics (it is a two-edition set, the first is mech and the second is E&M).
Any...
Well I'm having a quiz coming up on Electricity/Circuits, and I want to get an A on it :smile:.
However, regardless of the coursework I went through, I still have a few questions.*The Voltometer:
http://img242.imageshack.us/img242/5664/circuitcopy.jpg
It displays a voltage of 31.81 for the...
I am researching electric and magnetic fields, and so far from my understanding each electron produces its own electric field, negatively charged, and thus the atom has its own electric field, am I right so far? Some atoms have better current than others, this is related to the number of valence...
? I'm just curious. Also I'm having trouble with mechanics. I feel like i have no idea how to grasp fnet and calculating it. I also REALLY REALLY REALLY suck at drawing free body diagram. Math is a walk compared to physics which feels like a marathon. I'm actually not that great with math but...
During 4 hours one winter afternoon, when the outside temperature was 11° C, a house heated by electricity was kept at 23° C with the expenditure of 44 kwh (kilowatt·hours) of electric energy.
(a) What was the average energy leakage in joules per second (watts) through the walls of the house to...
Homework Statement
A solid sphere of radius R carries a volume charge density \rho = \rho_0e^{r/R}, where \rho_0 is a constant and r is the distance from the center.
Find an expression for the electric field strength at the sphere's surface.
Homework Equations
\int\vec{E}.d\vec{A} =...
Our electric energy is provided by power-station,for example a water power station.My question is,the water power station doesn't produce electricity all the time,then what provide the voltage in our houses?Do they store the electricity?(It seem to be impossible)In addition,if it begins to...
Are the mathematical electrical laws as accurate as mechanics laws, if the input is perfect enough, or they're just good approximations??
I mean ohm's law and potential difference = electric field times length of wire (in wires), and alike laws.
Hello All,
I am currently investigating domestic electricity use and whether or not the average (mean) per person use is affected by the number of people living in a household.
I have monitoring data from several hundred households with household occupancies ranging from 1 to 6 people...
The fuse in my House continues to blow. The fuse rating is 20 amps. I can easily make the fuse so that it can't blow out but I know that might heat the wires in the wall if I draw too much current, and can cause an electrical fire. I am wondering, If I get a high grade durable power...
Back in my physics class in high school, we had a homework problem that stated a car had a circular hood emblem (pretty much a Mercedes-Benz hood star) and that when the car was in motion it would produce electricity due to magnetic waves going through it while it was in motion.
I now own a...
http://www.facebook.com/#!/video/video.php?v=425444185921
Is there any merit to this? It seems like a commercial for "GS Filters" to me, but I've always considered the CBC fairly reputable.
Hi guys,
I was answering some questions on my physics homework and I didn't understand why the answer was what it was...
the first question was this:
1.) A hollow uncharged metal ball hangs from a silk thread. A glass rod has been charged by rubbing with rayon. When it is brought close to...
Homework Statement
A battery has an emf=6V. The battery is connected in series with an ammeter and a voltmeter. If a certain resistor is connected in parallel with the voltmeter reading decreases by a factor of 3, and the ammeter reading increases by a factor of 3. What is the INITIAL READING...
Homework Statement
[PLAIN]http://img186.imageshack.us/img186/6260/physicsquestion.jpg
Homework Equations
Not sure...?
The Attempt at a Solution
I believe the answer should be A or B.
I'm thinking the live and Earth wires will form a complete circuit. Since there is very...
Direct to the point,
Is it possible to convert Kinetic Energy into an Electricity or Electrical Energy?? How?? Without using...like wind, hydro, and etc...
In news stories about the countries suffering from energy crisis it is said that, let's say, the electricity shortfall has reached 3,000 MW while the generation is 5,000 MW and demand 8,000 MW. Watt is used for rate of energy, energy flow per unit time. Are they talking about the shortfall in...
hi friends,
i came across this piece of news...
"Until 2010, no solar sails had been successfully used in space as primary propulsion systems. On 21 May 2010, the Japan Aerospace Exploration Agency (JAXA) launched the “IKAROS” (Interplanetary Kite-craft Accelerated by Radiation Of the Sun)...
Homework Statement
the problem is attached to this post
Homework Equations
Req=1/R1+1/R2+... for parallel and Req.=R1+R2+... for series... Kirchoff's law for Current and Potential to be applied
The Attempt at a Solution
completely lost ... pls help
I've been reading about static electricity, and I'm starting to get a handle on how it works. I have a big question; static electricity always seems to make things stick and what not, but is there such thing as static electricity repulsing?
Well I guess it's pretty simple, I know E = IR, but I've been thinking of some situations lately that have been confusing me so I decided to ask here. The first one is how does a high voltage stun gun not create high currents? The highest I've seen is 4.5 million volts. I think they simply...
In the situation shown in the figure a particle having charge q is executing simple harmonic motion of amplitude A and time period T in front of a CONDUCTING EARTHED SPHERE of radius R. The reading of the voltmeter when the charge particle is at its mean position(at a distance r from the...
Homework Statement
1. Rod A has negative charge and is used to induct rod B. Rod C then charged by touching it with B. The charge on C is…
a. Neutral
b. Positive
c. Negative
d. Undetermined2. a. Plastic comb that we hold can be charged by rubbing. Why a copper can’t be charged when we are...
Homework Statement
1.a ball is attracted to both positive and negative charge. state whether the ball has negative, positive, or no charge
2.why does electroscope use gold for the "leaf"?can others metal be used?
3.http://www.sciencebyjones.com/induction.gif
i do not understand that...
Is it possible to convert electricity into propulsion force?
My friends and I are discussing about this subject. Is it possible to build a device which can convert electricity into propulsion force?
just so you know, we have incessant electricity produced by solar cells and if that...
A month ago or so, an idea popped into my head. Here it is in a nutshell: If you send a space device or ship in an orbit that takes it to do gravity assists over and over again to increase its velocity to generate lots of kinetic energy. If you do that, how much kinetic energy would be created...
Hi all
I'm a complete newbie to the subject of electricity and trying to wrap my head round it. To be more precise, I'm trying to build a mental model for myself that accurately predicts what goes on in circuits.
I've read several accounts that suggest a model based on the flow of...
In fuel cells hydrogen combines with oxygen (due to a catalyst) resulting in a potential difference. Is it not possible to burn the hydrogen and use the energy from this exothermic reaction to produce electricity? Since the rate of reaction of hydrogen combustion is quite high we could keep the...
Is there a way to make the atoms in HHO gas (Browns gas) to separte into it's elements; so the Hydrogen atoms go one way and the Oxygen in another way. By doing this I'm hoping to generate electricity from the reaction by bringing them together again. What kind of fuelcell do I need?
Hi guys, new to the forum so I apologize if I post in the wrong place or something. I'm in an engineering physics II class right now and honestly this material is so hard for me I feel completely overwhelmed (yet sadly I can't get my degree without it). I'm doing some problems right now and have...
when the terminals of a single cell are connected by means of a conducting wire with no resistor component is there a current flow through the wire ?
jus started with current electricity have a lot of doubts thanks for any help
time constance "capacitors" electricity
was looking over my physics electricity
i got some question actually i just forgot them.
v(t)=V(1-e^(-t/RC))
where RC is the the time Constance,
1) i am not sure what the time Constance means.
2)If R is increased by a factor of 2 what in theory...
In response to LA's threatened boycott of all things Arizona, an official of Arizona's version of a Public Utilities Commission (http://www.azcc.gov/divisions/administration/about.asp" !
This is getting uug-lee..
I understand that the electromagnetic field and light are tied together, and they all travel through big groups of photons and they all travel at the speed of light. And I get that light travels through empty space.
But I am wondering what does electricity and magnetism travel through...
Homework Statement
I was just wondering if someone could help explain this problem I've been having. A lot of textbooks I've been studying from are describing how two insulators can become charged, but then don't mention whether an insulator can be earthed - it only mentions "charged...
I was out in the shop earlier, and came back inside the house, noticed my watch fast a few hours.
Did a search to find out what kinds of things cause this, and found that it was probably the magnets/electrical fields from the power tools I was using.
Also came across a lot of people...
1. Find I1, I2 and I3, see attached file.
2. I1 = I2 + I3, U = R * I
3. Can't seem to understand why the current is going the way it is at I3 rather than the other way.