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.
Hi, I'm trying to make a realistic scene, in which water is kept under constant electrical charge. If the power is around 75 milliamps, and it's in a stream about twenty feet across by ten feet deep, would this affect water temperature? Thanks!
So far what i figured out is that R2 and R3 are in parallel, R1 and LDR in parallel. And these two parallel circuits are parallel to each other ( tell me if I am wrong)
The voltmeter has to read 0 but I am not sure how i can achieve that. Is there a rule where when the resistance of each side...
I'm a bit confused as to why can't you transmit AC current over a single wire.
For instance, say you have an AC generator which induces potential difference at different points of the wire and thus, creating current. Downstream, the wire can be split and applied to a load. When the wire is...
I am a high school teacher and we were discussing waves and electricity in class today. One of my students asked me if electricity is a longitudinal wave or not and I had no idea how to answer.
So, I realize that electric fields are what drive electrons to move through conducting wires, but...
Suppose you made a generator by connecting several magnets pushing currents through wires into a capacitor. Now suppose you connected this capacitor to another capacitor by a wire coiled around another wire both connected to the next capacitor. Could this work in creating more electricity for...
Researching for a Scifi novel that depends heavily upon electricity...something I don't know much about! Any input would be appreciated!
My situation: Somebody is trying to sneak through a high powered electric fence. Is it at all feasible to short out the fence somehow -- like, connecting it...
Hi! I've been struggling with this.
Original exercise here: Find the value of Iy when R=0. And the value of Vx when R is infinite.
For the first part of the question I did this since R=0:
I've tried to solve this circuit and I get that Iy and I5 are 0 A, and this can't be possible since Iy...
Hi everyone. I was just out in my back garden and was watching the water from someone's shower pour down the pipe and out into a drain. I was thinking if all of the used water from my house just goes down a drain then why not try make use of it.
If the water system continues after use and takes...
So I have taken up this course on Electricity and Magnetism and we need to prepare a project as in not very broad as such but for example, attempting to solve a problem or something that is related to the subject but off the course. I'd like to involve computation too in some form or the other...
Homework Statement
The circuit is the one in "Fig.4"
I need to calculate equivalent resistance between A and B. This is what I've tried:
I think that the first resistor is shorted by that wire connected between A and E. Their answer looks like this, in fig 2.2.1. I'm not sure if their...
Homework Statement
A conducting sphere has a radius of 2.25 m and carries a positive surplus charge of 35.0 mC. A protective layer of barium titanate is applied to the surface of the sphere to make it safe for laboratory workers nearby. Safety considerations dictate that the potential...
I'm working on a Scifi novel, and trying to make it somewhat...scientific! Any advice is appreciated.
Here's my question: I'd like to write about a situation where a body of water is purposefully kept under electric charge for years on end. This body of water would vary in size and depth, but...
I was told to introduce myself before asking a question. So, I'm a writer -- and that's why I joined this forum. My current project is Scifi -- with more "sci" than "fi" at certain points, haha! I AM NOT very scientific, so I'm hoping I can get smart people to answer some questions now and then...
<Moderator's note: Moved from a homework forum.>
Calculate the required voltage to produce a electric arc between 2 iron nails (distance: 3cm).
I´ve read in the internet that you need 1 kV per mm. But how can I calculate this value, that I need 1kV per 1mm?
I started having this problem with wearing slippers (or any shoes with rubber soles) in the house because the rubber, rubs the carpet and charges me up. Anything metal that I touch gives me a mild-nasty shock depending on how charged up I am. I tried different kinds of slippers and socks, I...
This is an inverting amplifier incorporating an ideal op-amp with infinite open loop gain. I have a simple question concerning the derivation of its gain (-R2/R1). The point I circled is at 0V (Virtual Earth) but then, if V+=V-, Shouldn't Vout=0 regardless of what R2 and R1 are?? What's wrong in...
Hi all
Interested in making an electrostatic generator, anyone have experience of building one and also what type would be the most efficient build induction or friction based? Lots of info on the net regarding the principles but and good books for this or websites?
Also how best to...
If electrons move as current flows through a conductor, what happens when a wire is grounded? Do electrons flow in the ground??
If they do, will it effect the number of electrons in the circuit which starts from power plant such as dam and comes to our homes through a grid station?
Will it not...
I would like to measure time period of very short periods of electricity flow in the range of micro seconds or even smaller;can someone tell me me a device that can help me do this?
I often get confused that why we have to use the ancient idea for the direction of current flowing.I have come to know a very weak reason for it.It is said that when current was first discovered,it was assumed that the current flows from the positive region to the negative region(using the idea...
I'd like to start a thread of thoughts and opinions of a topic that I am considering spending time and money on. Unfortunately, I do not have a very broad knowledge of the engineering intricacies of the topic. I'm really curious if there has been a proposal or workings of a vehicle that uses an...
Homework Statement
https://www.bpho.org.uk/user/pages/05.past-papers/06.as-challenge/_general/BPhO_AS_2010_QP.pdf
12. A combination of resistors shown below represents a pair of transmission lines with a fault in
the insulation between them. The wires have a uniform resistance, but do not have...
I'm currently in a undergrad level course of eletromagnetism and my professor found it useful to remember quickly of some relationships that we see in high scool, among them power waste.
I got the formulas, since they're simple and are direct derivated from the definitions of electric current...
Could somebody help me out with this combination circuit? The answer that I get is 62K but that is not one of the answers. At first, I thought the 10kohm and 20kohm wherein series and the other side as well. Then I thought they are all in parallel because of the different current flow they all...
Homework Statement
Given two things spherical shells radii r1 and r2 with r2 > r1.
The inner she'll is charged uniformly with a total charge Q1, while the outer shell with Q2.
A) use gauss law to computer the electric field everywhere
B) Use any method to calculate the potential everywhere...
Homework Statement
Given two very long lines each is charged with linear density +lambda Coulombs/meter. The two lines are separated by a distance of d metres.
A) show the electric field E, at any point along one of the lines due to the other line is
E = lambda/(2 (pi)(epsolon o)(d))
(Note...
Homework Statement
In addition to the question given in the attached file below, I don’t understand how is the polarity changing periodically.
Homework Equations
Concept-based question, I guess.
The Attempt at a Solution
I have no idea how should I approach the question. So, if anyone has an...
Homework Statement
A charged cork ball is suspended on a light string in the presence of a uniform electric field.
E=(3×10^5 N/C)i+(5×10^5 N/C)j. The ball is in equilibrium in the field.
Find the charge on the ball. The acceleration due to gravity is 9.8 m/s2 . The mass of the ball is 0.7g. The...
Is it possible to generate static electricity from air flow containing particles example smoke or dust flow, or does anyone know of experiments such as the kelvin water dropper converted to generate static from air flow ?
Thanks
Can you charge a capacitor with magnet and wire? Can a wire attached to a capacitor be given amperage by a stationary magnet? Can the wire be made to a short length so that the magnetic field creating the current causes the current to reach the capacitor to charge it? I imagine this doesn't...
Hello
What are benefits of nuclear power plant electricity than hydro power generated electricity
Does it cost less per unit any or the waveform is pure sine wave
how engineer build it .
The attempt at a solution
(Assuming the components are in series of this order: resistor, inductor, capacitor
So I know that the phases are not in sync, that as the voltage oscillates the voltage across each component in the circuit is different.
At the peak voltage aka peak current the voltage...
The Faraday's law and Lenz's law together give you, $$\xi = -\frac{\partial\phi_B}{\phi t}$$ or put another way,$$\vec{\nabla} \times \vec{E} = -\frac{\partial \vec{B}}{\partial t}$$. My question, I am just asking to make sure, the spatial dependence of ##\vec \nabla \times \vec E## will be the...
Hi,
I am taking GRE Physics this year and I am preparing from Conquering GRE Physics book and I have covered everything in that book on Electricity and Magnetism (yet to study Optics and Waves).
My question: How much from Griffith Electrodynamics book do I need to study? Or is the material in...
1. Problem Statement:
Find positions on the x-axis for the charges Q1 = -1 C and Q2 = +3 C so that the electric field is zero at x = 0.
Homework Equations :[/B]
I'm thinking I need to use Coulomb's law for this one. I'm just having trouble figuring out where to start. Coulomb's states E=kQ/r^2...
I know that the right hand rule applies for induced currents, and the left hand rule is for motors, but why? It doesn't seem to connect with any other physics laws and is very counter-intuitive that the current will flow in one direction rather than the opposite direction if both are...
I read somewhere PE=KE, how? It mean we can get transfer 100% PE to KE and KE to Joule
Please anyone can explain?
If I throw mass of 1000kg from 50 meters height can I get energy equal to Pe=mgh = 1000*9.81*50=490500 Joule? It mean 490500Kn = 490500watt= 490.50Kw.
Is it possible to to get this...
Why does my laptop's screen refresh every time I bring a metal object (any size) to my electric lighter?
-Happens when I am 1 foot away from the laptop
-1 foot away from the external monitor's wires (HDMI & power)
1. Video footage (MUST WATCH)
NOTE: the laptop screen also flickers a bit
NOTE...
Hi...Here is a GIF of some electrical explosions that I recorded with my full spectrum camera. These power lines supply power to a neighboring county so it didn't affect my area. In the upper atmosphere we see something similar in Transient Luminous Events (TLEs). In the case of the blue in Blue...
Homework Statement
Homework Equations
gauss law
q=charge on sphere
Q=total charge enclosed by gaussian surface
Q=alpha/r x (4/3 pi r^3-4/3 pi R^3) + q
The Attempt at a Solution
EA=Q/ε[/B]
E=Q/(Aε)
now
for E to be independent of r,
alpha/r x 4/3 pi r^3 + q = 1/(4)(pi)(r^2)
alpha x 4/3...
Hi guys i have a question i want an answer to let say i have an object that is negatively charged and another object positively charge and i connected them with a wires to a light bulb will they generate electricity and the object never lose their charge let's they they have unlimited charges.
Homework Statement
Homework Equations
F = k(q1q1/r^2)
K = (mv^2)/2
The Attempt at a Solution
I got number 18 easy enough, number 19 seems simple but I'm not getting the right answer. I'm calculating Force exerted by each charge on the new charge using F = k(q1q1/r^2) for the three charges...
We're all told how circuits have to be closed and loop back to be able to have the electrons flowing and give things power, so is that the reason most outlet charges have two wires connected? If so, why are phone chargers only one wire, and how are they so thin?
Thanks!
Homework Statement
Homework EquationsThe Attempt at a Solution
I often do circuit. But still there is always stuff i don't get..
I was asked to find
1) I1 I2 I3 immidiately after S closed
2) I1 I2 I3 after sufficient of time
3) I1 I2 I3 immidiately after S opened
Just give me clue please...
Homework Statement
A circuit contains a capacitor of capacitance C, a power supply of emf E, two resistors of resistances R1 and R2 , and a switch S2 . Resistor R1 is in series with the power supply and R2 is in parallel with the capacitor and the power supply. S2 switches the branch that...
Sorry if this is a bad question, but would lower costs to produce electricity (e.g. hydroelectricity instead of solar) bring down the overall costs for us consumers? Also, if there is any reading material or website on this topic, that would be really great too! Thanks!