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.

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  1. T

    Equivalent electrical resistance

    Hello guys! It's been a while since I last had to deal with direct current and I'm having a hard time solving the equivalent resistance for a simple circuit. I know this is rather simple, but I can't find my notes, so, could you please help me? The photo of the circuit is attached...
  2. R

    Electrical tester to record pulses?

    Hi, I'm Russell and new to the forum. By the looks of things there are lots of interesting topics and plenty of helpful people here, so I hope you can help me. I'm having a problem with the communication between a bagging machine and weigher. The pulse signal from the PLC that tells the weigher...
  3. K

    Programs Electromagnetism for an Electrical Engineer Major?

    I know I'm an electrical engineering major but I'm looking to get the most out of my courses. I'm curious about the significant differences between the two intro to electromagnetism courses offered at my school: the "engineering" and the "physics" versions. I'm not sure I get the whole applied...
  4. mishima

    Engineering Physics Teacher to Electrical Engineer

    I'm currently a high school physics teacher with BS in Physics and Astronomy, and will have a master of arts in teaching (physics) by this summer. I was just curious what it might take to start a career in electrical engineering at this point. Would I have to do an entire EE degree? Or could...
  5. B

    Net electrical flux on a cylindrical Gaussian Surface

    Homework Statement a cylindrical solid of charge q, radius R, and length H. The Gaussian surface S is a cylindrical shell of radius r and length h, with r < R. Determine the net electric flux given that q = -48Q, R = 4L, H = 3L, r = 2L, and h = 2L (type the integer value, along with the sign...
  6. R

    Mechanical or Electrical Problem?

    Last summer, I was taking apart a fan because it wasn't working. It turned as I expected that it was a burned out motor. Now one of my co-workers was a little upset at me because I had called it an electrical problem or failure. He said a burned out motor is a mechanical failure. Was he...
  7. L

    Programs Minoring in Physics, Majoring in Electrical Engineering

    Hi, I am a Senior in High School taking a lot of STEM classes. So far, I have really enjyed my physics class and AP Chemistry. I am in the 80th percentile for math in my school, taking Precalculus at the college level (the highest my HS offers is AP Calculus). I am an Amateur Radio Operator...
  8. S

    Sizing Power Supply in Electrical Cabinet

    What things do I need to consider when selecting a proper sized power supply? Basically this is control power, ouputs are pushbutton lights, alarm horn, and solenoid valves. Do I look at the peak inrush current? Average holding current?
  9. A

    Getting started with Electrical Engineering

    Getting started with Electrical Engineering! Hello, I'm a high school student 15. I want to start building or working more with electronical systems. I build robots some. But i want to get into it further the core of that. With constructing chips (from pre printed boards), networks, high...
  10. G

    Engineering Nodal Analysis on Electrical Circuit

    Homework Statement The Attempt at a Solution According to the similar problem Node X: I1=(22-Vx)/66 I2=(66-Vx)/44 Il=Vx/264 I3=I1+I2+Il Node Y: I4=Vy/240 I5=6 I4=I3+I5 After the calculations I get 1.08 for Vx, which I think is wrong. Thanks
  11. D

    Electrical Noise: Shielded Cables & Earth Grounding

    I work with industrial electrical system and I got a question regarding electrical noise caused by electromagnetic radiation. In an industrial environment, cables carrying an analog signal are shielded and its drain wire is Earth grounded at one end of the cable. When electromagnetic radiation...
  12. I

    Electrical Appliance working on alternating current

    The magnitude of current of alternating current varies with time The power developed by the electrical appliances, let's say an electric fan, also varies with time But why the fan can still operate uniformly? Or the AC is changed to DC in the electric fan?
  13. J

    Electrical and gravitational forces of protons

    Homework Statement At what distance between two protons are the electrical and gravitational forces equal?Homework Equations electromagnetic Force = k(Q1*Q2/r^2) gravitational Force = G(m1*m2/r^2) Constants: k = 9.0*10^9 (N m^2/c^2) G = 6.673 × 10^-11 (m^3 kg^-1 s^-2) Charge of proton...
  14. G

    What is the validity of this electrical circuit?

    http://img15.imageshack.us/img15/771/captureuce.png Homework Statement Determine if the circuit is valid or invalid. Homework Equations The Attempt at a Solution Please note which node I used as the ground node and which node I have labeled V_{1}. By the node voltage method...
  15. 0

    Confused on the Electrical Energy Formula?

    This is probably a silly question. The Electrical energy formula is this: Ee = k(q1)(q2)/r So let's say a positive and negative charge are directly next to each other. Conceptually, there should be no potential energy there. But the formula (r=0.00001m) suggests that it is huge. On...
  16. A

    Which 2nd Bachelors would best complement a BS in Electrical Engineering?

    Having graduated 3.5 years ago, and being unable to get an entry level EE job (I went into an unrelated field right out of college and have tried getting an entry level EE job for over 1 year now), I need to make a decision. I'm starting to think the only way I can get an engineering job is to...
  17. G

    What Is the Relationship Between Voltage and Length in an Electrical Circuit?

    Homework Statement So I was wondering if someone could help with part C. I have gotten the answers for A and B, at least I hope they are correct. Homework Equations The Attempt at a Solution So I'll just do the rectangle first and then try and solve the trapezoid. By the way...
  18. M

    Electrical Question - Grid Tie Power Inverters for Home Use

    Electrical Question -- Grid Tie Power Inverters for Home Use Since we are being careful let us assume we have a doll house that is powered by only a 12v source. Inside the doll house, Julie, the doll living there, gets it in her head to construct a 1.2v solar system on the roof of her doll...
  19. F

    Good ideas concerning shortening and lengthening electrical impulses

    Hey Basically, what I am wondering is if anyone has any great ideas how to change the electrical impulses from an impulse source giving steady pulses if you can't change the settings of the source. What I would like to do is make send these impulses through two separate branches (they...
  20. Greg Bernhardt

    Essentials of Electrical and Computer Engineering by David V. Kerns Jr.

    Author: David V. Kerns Jr. (Author), J. David Irwin (Author) Title: Essentials of Electrical and Computer Engineering Amazon Link: https://www.amazon.com/dp/0139239707/?tag=pfamazon01-20 Prerequisities: Contents:
  21. B

    Engineering Electrical circuit porblem using ohms law

    Homework Statement Using all the following resistors : 2 x 12 ohms , 2 x 24 ohms , and 2 x 36 ohms. create a circuit where the total resistance will be 4 ohms. The problem states that I have to use ALL of the resistors..making it so complicated Homework Equations 1/Req = 1/R1 + 1/R2...
  22. K

    Philosophy, Electrical Engineering, Jobs and Loans

    I currently have a BA in Philosophy from 2008 and am interested in getting an MS in Electrical Engineering. Are the loans worth it? Does the salary typically outweigh the cons of the loans? How is the employment out there for electrical engineers? Does anyone have any idea as to how my BA...
  23. T

    How to obtain Electrical Characteristics/Model of a lump of Powder ?

    How to obtain Electrical Characteristics/Model of a lump of Powder ?? Dear All, I have some powder given to us by a chemical engineer. Now, i lumped this in a syringe and connected wires on both sides. Can you give me an idea of an experiment that I can conduct to provide me with the...
  24. Low-Q

    Efficiency of electrical heat vs. mechanical heating

    I have a question about efficiency of electrical heating vs. mechanical heating. Let me explain an example: I have two containers with 1 litre of water each. In one container I use a electric heater (electrical resistance) 1W. In the other container I use an electric motor attached to a...
  25. T

    Clarification of electrical terms

    I am embarrassed to be asking such an elementary question, but I want someone to explain the difference between amps, watts, and joules. I tried a dictionary, but it wasn't specific enough.
  26. I

    Is all electrical energy eventually lost as heat in solid state electronics?

    I've never heard it said before but it appears to me that all electrical current that flows in a solid state component system; processors, diodes, transistors, resistors, etc. is eventually dissipated as heat. What are your thoughts about this?
  27. S

    Calculate the Ratio of Ib/Ia in an Electrical Circuit

    Homework Statement Part of an elecrial circuit for the olympic score board consisted of a single battery V and several resistors having on of two values. R or 2R. They are hooked up in the confriguration as shown. Calculate the ratio of the two currents shown Ib/Ia...
  28. R

    Solving Electrical Circuit Puzzle: Voltmeter & Transistor

    Homework Statement http://web.stagram.com/p/362176186041336029_243276631 this is a link to the question. I'm stuck on 2a and b Homework Equations I don't understand if the voltmeter is reading 6v why the light is not receiving 6v? And why would a transistor help this problem? The...
  29. J

    Electrical power out of R134a phase changes

    Hi My 2'nd year of engineering doesn't quite let me to find an answer to the following problem: In a nutshell: I want to use rankine cycle to extract 5kW worth of electrical energy from a system utilizing R134a as working fluid. The properies of R134a are as follows: Tag R134a...
  30. B

    Creating static electricity from an electrical current

    Is it possible to use an electrical current (from mains electricity) to create static electricity on a conductive surface (that is not earthed) without the two coming into direct contact? See attached image.
  31. N

    How circuit breaker electrical system clears ground faults.

    Hi I am taking generals now but I will eventually take EE degree. I am studying electrical systems now. Can somebody help me on system configuration regarding circuit breakers clearing ground faults? In this picture (the bottom figure), if X2 faults at the transformer, would the fault...
  32. R

    Force on Three Parallel Electrical Sheets

    Homework Statement Consider three plane charged sheets, A, B and C. The sheets are parallel with B below A and C below B. On each sheet, there is a surface charge of uniform density: -(4/3) * 10^-5 (Call α) -(7/3) * 10^-5 (Call β) -(3/3) * 10^-5. (Call γ) (The density given includes...
  33. G

    Computer or electrical engineering-electroptics

    Hello, I am a newbie on this forum (I registered yesturday). Right now I am in high school and doing very well in Math and Science. Soon, I will have to go to college in engineering. Electrical and computer engineering are the most interesting branches in engineering. But I do not know...
  34. N

    Forces Involved in an Electrical Motor According to Newton's Law

    Hi Everyone. I've been trying to build an electrical motor and would like know the method to actually calculate the forces exerted on several parts in the motor according to Newton's laws. I've attached some pictures and drawings of the motor I'm trying to build. There are two scenarios that...
  35. A

    Direction of electrical force in coloumb's law

    is there any theoretical proof why force between the two charges act along the line joining them (acc to coloumb' s law)
  36. Y

    Electrical Engineering After Physics Background

    I attend a small LAC. After having taking an electronics course this past semester, I am fascinated by it. While I am still interested in Physics, I would like to skew more towards EE while in grad school (maybe, Quantum Devices, Solid State, etc). Am I in good position to apply to such things...
  37. D

    Engineering Job after Electrical Engineering Technology

    Hey all I graduated in 2009 with 2 Bachelor of Arts, worked for 3 years (profesionally as a marketer and doing PR) but didn't enjoy my career and wanted to transition to electrical engineering as I was looking for more stability in my future career prospects. I started off with a 2 year...
  38. T

    Considering a PhD in EE: Mechanical or Electrical Engineering Focus?

    Just finished with my B.S.M.E. and now my M.S.M.E. and have been considering a Ph.D. in Electrical Engineering. I've been offered research opportunities in both the mechanical and electrical engineering departments, so really it's up to me to decide. Can anyone put an industry spin on what I...
  39. S

    Squar Electrical: Overview of Electric Company

    what is the squar electrical?
  40. B

    Electrical Energy Electron Question

    Homework Statement Two electrons are fired at 3.5x10^6 m/s directly at each other a) calculate the smallest possible distance between the 2 electrons me=9.1x10^-31 Ve1=3.5x10^6 m/s qe=1.6x10^-19 C Homework Equations Em1=Em2 The Attempt at a Solution Tried using Em1=Em2...
  41. C

    Effect of electrical field on annealing of thin film bismuth

    I have been reading recently on the properties of evaporated thin film bismuth, particularly grain size and resistivity. Usually evaporated bismuth is amorphous and semimetallic, with very small grain size. Grain size can be increased and resistance lowered by annealing the film. It has been...
  42. T

    Engineering PhD in Electrical and Electronic Engineering

    Hi, I have a master of science degree in photonics. I wanted to pursue a career in photonics related fields. My major interests are in nonlinear optics,laser physics,fiber optics and material science. I have received an offer for PhD in electrical engineering(micro-systems and photonics...
  43. A

    Temperature dependence of the electrical resistivity of a metal

    the electrical resistivity ρ of a metal is proportional to the probability that an electron is seattered by the vibrating atoms in the lattice an this probability is in turn proportional to the mean square amplitude of vibration of these atoms.How dose the electrical resistivity ρ of the metal...
  44. M

    Electrical Engineering - Increasing the Time an Alarm will Buzz

    Homework Statement The problem is to create a small alarm that will buzz approximately 6 seconds before it stops buzzing. I managed to create a working alarm, only problem is mines will buzz for around 1.5 seconds not six. Homework Equations τ = RC V = V0e-t/τ The Attempt at a...
  45. P

    Electrical Engineers: Need help with thermostat output options.

    I'm working on a project were I will be using Heating Plug Element- http://www.omega.com/ppt/pptsc.asp?ref=CSS_CSH&Nav=head01 I want to be able to control temperatures up to 1000 F using something likes this: http://www.omega.com/Manuals/manualpdf/M4636.pdf I would like to be able to...
  46. G

    Electrical Resistance of a Sphere?

    How does one find the electrical resistance of a homogenous sphere of uniform density? By connecting two wires across the diameter of the sphere, and assuming Pouillet's Law R=ρ\frac{L}{A} holds.
  47. J

    Engineering Electrical Engineering - Circuit w/Buzzer Help

    Hi guys, I've been using your forums for quite a while to help reinforce my physics principles, and only just made my account. I wanted to know if there were any electrical engineers that would be willing to assist me with some guidance in a small design challenge. Homework Statement Here are...
  48. O

    Engineering Electrical Engineer Certifications?

    I'm wondering what are some recommended certifications a soon-to-be college grad should get as an electrical engineer besides an E.I.T.?
  49. O

    Which electrical engineering subdiscipline uses the most math?

    Between control theory, photonics/optoelectronics/semiconductor devices, electromagnetics (antennas or other application), which of these fields has the potential to expose me to the most mathematics in graduate school?
  50. B

    Electrical, calculate capacitances

    1. Homework Statement d.c supply 200V capacitors A and B connected in series p.d across A is 120V p.d. across A, increased to 140V when a 3μF capacitor is connected in parallel with B. attached diagram for better understanding. Find capacitance of A and B. 2. Homework Equations...
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