What is Electrical: Definition and 1000 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.
I'm going to ask a very basic question and my attempt at solving it may not even be right.
Electricity is basically flow of electrons in a conductor, so what I was wondering is if I start heating the wire the atoms will start losing the electrons and everything will be moving in a chaotic way...
Hi
I was reading The Comprehensive LATEX Symbol List which is available at
http://www.tex.ac.uk/tex-archive/info/symbols/comprehensive/symbols-a4.pdf
On page 70 , in Table 215, they have given wasysym Electrical and Physical Symbols. I tried to insert
one symbol here on this forum, but...
One advice I received on choosing a major is pick what you are good at and what you like while keep in mind what future career you might have. Even though I was just accepted into the EE department after my freshman year, I am still unsure if I really want to do EE.
Would someone please give...
These are questions for electrical engineers involved in electrical power transmission by overhead line and knowledgeable about current practices.
- What catenary sag is normal, under normal conditions of weather and transmitted current?
[obviously the answer will depend on the distance...
I am studying to be an electrical engineer and want to use what I am learning in a hobby. If there is any engineers that have an electronic type hobby what is it and where did you get the idea from?
So, I'm a computer science major because I love programming and maths, but I really want to also learn the hardware part of computers as well.
My university doesn't have an electrical engineering programme or offer any serious courses dealing with electrical engineering. I really want to learn...
I have a request for some explanation in Feynman diagram concerning repelling/attraction of electrical charges. I have been told that when two charges (say, e1(-) and the e2(-)) repel each other, a photon is being emitted from one of them, and the other charge is later being hit by this photon...
I have done my Undergrad in Electrical Engineering and I have close to 8 Years of work experience in PCB design and mostly in Validation. I have done Signal Integrity and bit of Power Integrity validation for boards.
I would like to move towards Signal and Power Integrity field. In that case...
Hello there and thank you for taking your time to read this. Well my problem is that I can't decide if I should double major or not. I am going to be an incoming freshman to college with my intended major being physics. I wanted to double major with EE because I find it to also be interesting...
Every time I walk by the electrical transformer at the end of the lane, I hear a low humming noise(≈50Hz) that is continuous. I have observed this in all types of fans. I grab the hub so that it is not able to rotate and switch it on. Then I hear this hum. When the mixer/grinder chokes, it...
I'm on my final year of my Electrical Engineering Degree, and I'm just needing some guidance on what I should base or do for my final project.
Any help, links or possible designs would be fanastic!
Cheers Hayden
please help me solving 2 electrical network problems
file:///C:/Documents%20and%20Settings/user/My%20Documents/My%20Pictures/From%20RSPC_Pashya/Camera%20roll/WP_000127.jpg
In first problem I have to find current through 5Ω resistor using Thevinins eq.
So, in first step i removed 5Ω...
Hello, as a chemist I sometimes run into mechanisms or reactions that are explained through the use of an electric quadrapole moment. I've spent some time looking at various sources, and I'd like to summarize what I believe it is. Hopefully someone here can provide feedback on my...
Hi guys, I've realized that to truly, deeply, and fully understand something it often helps if you think about the conservation of energy, and then just build up from that.
So here I have tried to explain why a battery has a voltage, and why there are voltage drops across resistances...
Homework Statement
Reduce the Expression:
15sin(wt-45°) + 5cos(wt-30°) + 10cos(wt-120°)
to the form Vmcos(wt+θ)
Homework Equations
The Attempt at a Solution
My theta value at the end isn't coming out right.
My first step was to put make sure each term was in terms...
Homework Statement
Homework Equations
The Attempt at a Solution
I am not really sure how to optimize it from here. What should I be taking the derivative of the price function with respect to ??
Ok I know there will be a life long battle between EE's and EET's. This thread is not about the Pros and Cons of the two programs. I am well aware of what each program has to offer and how they differ academically. I understand there will always be some people who look down on EET's.
I...
It needs to perform at least 50 cycles with a cumulative error of no more than [+\-] 30 minutes. This is for a home project.
Any suggestions of components?
Hi,
I am a new business that has ordered some electrical equipment.
The first is a packing machine and the plug that the machine is being sent I have attached to this post.
It is listed as 220v, 3 phase, 50hz but NEMA does not show this to be the same specifications.
How will I make...
Hi everyone! Design of electrical systems for buildings is the field I want to engage in the future. I have already basic concepts learned about this. But I want to improve myself in this field. I am looking for a reliable and organized reference. Please help me choose the book/reference I...
Homework Statement
http://img801.imageshack.us/img801/4227/capturebsw.png
Homework Equations
The Attempt at a Solution
Alright I'm not really sure how to solve this problem. I have redrawn the circuit below without the operational amplifier. In ideal operation amplifiers there's no...
Hi all,
I have been searching the internet for explanations on the method of ERT, but they are in general extremely complex and contain very specific vocab that I'm not understanding.
Would somebody care to explain to me the method of ERT in language that an A Level student can understand...
Homework Statement
Charge of uniform density 4.50nC/m is distributed along the circle of radius R. What is the electrical potential (relative to zero at infinity) at the centre of the circle?
Answer: 254V
Homework Equations
electric potential: V=kQ/r
The Attempt at a Solution
Because the...
Hello,
Let's say I am generating 5 amp at a constant 1 volt and storing it in a battery without any loss of energy. The question is what am I adding to the battery? Am I adding power as a function of time or is it something else? So say if I were to calculate how much energy has accumulated...
Homework Statement
Hi.
I'm having some trouble calculating the electrical current density, which in my case is given by:
\sigma =\frac{{{e}^{2}}}{4{{\pi }^{3}}}\int{\left( -\frac{\partial f}{\partial \varepsilon } \right)\tau \cdot \mathbf{v}\cdot \mathbf{v}}\,dkHomework Equations
Lets...
Hi All,
Since I myself hate reading long posts I will cut to the chase.
I graduate in June with a B.Sc in electrical engineering and am hoping to go for graduate studies. During the last four years I took courses in almost all areas of electrical engineering.
The only field I liked AND...
1. A 23 cm diameter circular saw blade spins at 3800 rpm. How fast would you have to push a straight hand saw to have the teeth move through the wood at the same rate as the circular saw teeth?
Homework Equations
v=wr
τ=Iα
τ=rFsinθ
The Attempt at a Solution
tried to multiply the...
So an insulated electrical wire coiled around metal can create an electromagnet, but what happens if the same wire isn't insulated, and simply makes direct contact with the metal object it is coiled around, does the magnetic field shift then as well? Would there be any other side effects...
Homework Statement
A point charge q1=5μC is held fixed in space. From a horizontal distance of 6.00 cm, a small sphere with mass 4g and charge 2μC is fired toward the fixed charge with an initial speed of 40.0 m/s. Gravity can be neglected. What is the acceleration of the sphere at the...
Long story short, I graduated in 09 with an EE degree from a good school. I went into an unrelated field for a few years and decided I missed engineering and want to get back into it. Getting a job has been impossible since companies want fresh out of college, or experienced, and now I'm neither...
Why is it that introducing more loads in a parallel circuit decrease equivalent resistance?
While we're on that topic, why is equivalent resistance, a changeable attribute, the resistance of a battery?
And why is the voltage and Current in a series circuit the same across all loads, if the...
Hello, I'm a high school student who is doing a career project. My interest is in electrical engineering, and I need to interview a professional in this field. For someone who is answering these following questions- it would be great if you would answer thoughtfully. If you would like to answer...
Homework Statement OK, this is a project given to a group of us. I don't really know whether this is a homework question, if it isn't please correct me frankly. We need to make a toy that is really cheap, and quite innovative. I don't need any suggestions whatsoever, but I have got some ideas...
I seem to be at a stalemate.
I have an interest in the workings of all things, I enjoy getting my hands dirty and getting hands-on with my job and designing new things which mechanical engineering gives more opportunity for (I understand somewhat that they have other people to do that for...
Given the power that is needed to be output by the capacitor - P
the length of time that the capictor must give off that power - t
the maximum operation voltage that the capacitor can operate at- V
the dialectric constant of several materials - ε
the breakdown field of those several...
Homework Statement
Hi, I have a couple different problems that I did not understand.
I have the images here.
The problems which I did not understand were: 12, 13, 17. [EDIT: I calculated answer to 12 using conservation of energy.]
For 13, I know how the graph looks; however, I'm not sure how...
Problem
Given the power that is needed to be output by the capacitor - P
the length of time that the capictor must give off that power - t
the maximum operation voltage that the capacitor can operate at- V
the dialectric constant of several materials - ε
the breakdown field of those several...
I'm in my first year, which is a HNC. I'm currently thinking of what I'd like to do once I graduate, my idea is to get a job in doing the field of electrical engineering I like most, then maybe starting a company in doing that once I felt confident in what I was doing. I'm just unsure of what...
hello,
i am an undergraduate student pursuing engineering.
kindly suggest me a good book on electrical machines (induction motors, dc motors ,etc) so that they can be understood very easily .
please suggest as fast as possible
:cool:
Hi,
Homework Statement
I'd like to find the electrical field at the center of a hole made in a hollow sphere of radius R0 with uniform charge density σ. The radius of the disc-shaped hole is a << R0.
Homework Equations
I know that the electrical field of the sphere is Q/r2 for r>R and 0 for...
I'm a mechanical engineer by training. At my current job, I'm designing automation equipment for various processes. Part of that design involves designing basic power circuits to power all the Controllers, robots, PLCs, sensors, etc..
I'm looking for national or state (Massachusetts) codes on...
Hi Guys,
I am building an equipment to Zone 2 explosive atmosphere.
Machine will be powered by the pneumatic motor. I just had an argument with my boss. He says that I need to order an atex approved motor and I say that I don't because the motor will never produce any spark.
What are your...
So I was thinking, I never heard about gravitational potential, yet there is such a big deal about electrical potential. Why is it so much more important that voltage be taught, yet no mention of its gravitational analog?
Hi in a homework problem I'm trying to solve circuit. I'm getting the output current of an operational amplifier going into the operational amplifier. Is this allowed? If not than I'm violating Kirchhoff Current law and my other calculated values of the circuit must be wrong.
Thanks for...
A branch of multi-level parallel circuit has 6 leads coming into it and currents of 3 A, 4.4 A, and 8.8 A flow into it, and one of the leads has a current flowing out of it of 6 A. If the other two leads have identical currents flowing out through them, what are those currents?
Any help would...
Homework Statement
Dry air will break down and generate a spark if the electric field exceeds about 3.0\times 10^6 N/C How much charge could be packed onto a green pea (diameter 0.81cm ) before the pea spontaneously discharges?
Homework Equations
E = kQ/r^2
Q = Er^2/ k <-------this is the...
Hi everyone I have a tough choice I have to make, I still have time, but I've been thinking about it for a while now. I'm currently in my second semester at a local university. I live near Detroit and my life dream has been working for an automotive company (or at least in the automotive...
Hello. So I've got an electrical circuit on page 4 of this: http://www.iuventa.sk/files/documents/2_olympiady/fo/54.%20rocnik%202012-2013/ulohy%20a%20riesenia/skolske%20kolo/f54skcul13.pdf and I am to calculate the total resistance of the circuit, but I have no idea on how to solve that strange...
Edit: I suppose this should be in the Academic Guidance section, sorry!
To be a little more specific, I want to be a physicist focusing on electricity, but I want to study practical applications and I do not want to wander through equation after equation. :)
I am currently a freshman at high...
Hello world.
I've been studying up on the fundamentals of electronics and have started with an abstract on atomic particles.
My understanding is Electrons have a lighter mass and have a negative charge, Protons have a heavier mass and have a positive charge. Neutrons have a mass greater...