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. J

    Electrical nodal analysis, find current

    Homework Statement ive tried many things and can't seem to grasp the concept of KCL.i know the node I am looking for is between r1 & r3. i assumed i1+i2=i3. also looking for directions of currents. V1=30v V2=40v R1=82 R2=68 R3=47 Vx = ?Homework Equations i1 + i2 + i3 = 0 ? The Attempt at a...
  2. J

    Electrical vs electronics engineer

    hello, I'm wondering the difference between electrical engineering and electronics engineering. Or are they the same but just some universities call it differently?
  3. K

    Osmotic pressure difference,pressure and electrical potential difference.

    I have an exam on monday, for a course I'm not familiar with. I have studied the material and tried some example exam question but I can't seem to figure out how to get to the result of the following questions. Q1: Homework Statement A sample of hydrogel is in equilibrium with a sodium chloride...
  4. T

    Differentials/ second order/ electrical vibration

    Homework Statement A simple series circuit has an inductor of 1 henry, a capacitor of 10^-6 farads, and a resistor of 1000 ohms. The initial charge on the capacitor is zero. If a 12V battery is connected is connected to the circuit, and the circuit is closed at t=0, find the charge on the...
  5. L

    How to convert soundwaves into electrical energy?

    I'm sorry to be annoying on this forum, I am new to the physics world! I am an undergrad taking physics I but am also doing a directed study on acoustical physics, sort of. I just need to write a paper on something along the lines of acoustics and their uses in communicative devices like...
  6. M

    Neuron Electrical Model, time constant

    Hi all, I'm trying to understand the electrical model of a neuron, and I have 2 questions. I'm a little confused about the time constant in this electrical model of neuron recording: The time constant shown is tau = C*(Rm*Rs)/(Rm+Rs), which implies that the resistors are in parallel...
  7. B

    Where can I find a list of electrical symbols for different sensors?

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  8. E

    Which Engineering Discipline With Physics (Mechanical or Electrical)

    I'm currently an "exploratory engineering" major at the university- which pretty much means I'm still taking interdisciplinary courses and haven't chosen a discipline yet. I want to continue with my engineering education but I'm also interested in physics. The college of engineering offers...
  9. B

    Relativistic electrical varialbes

    Hi, 1) How does the electric circuit variables such as Voltage, Electric current, and Resistance vary between two frame of references? 2) Based on (1): If someday we build a spaceship that move with very high speeds, are there issues to consider regarding the electric circuits in the ship?
  10. R

    Semiconductor Electrical Field?

    Homework Statement The electron concentration in silicon at T = 300K is: n(x) = 1016e(-x/18) cm-3 where x is measured in μm and is limited to 0 ≤ x ≤ 25. The electron diffusion coefficient, Dn = 25 cm2/s and the electron mobility is μn = 960cm2/Vs. The total electron current density is...
  11. J

    Calling in all Electrical Engineers- Final Year Project help needed

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  12. M

    Converting Directly into electrical energy

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  13. N

    Electrical service for a VFD motor

    I get very confused with AC electrical service, I'm a mechanical engineer so these things just confuse me. DC makes perfect sense to me. Anyway, I need to supply a single phase motor with 230V (the specs say 230V +/- 10%), so that would make my tolerance 207V to 253V. The motor is for a...
  14. K

    What's the electrical power (physically)

    I have a question to depth understanding electricity what's the thing that make electrical power appear? I mean that when generating electrical power We generate emf (voltage) and if the circuit was closed we get current ! HOW THEN ELECTRICAL POWER APPEARD AS AN IMPORTANT PARAMETER
  15. B

    Electrical schematic troubleshooting program?

    I was wondering if there was a simple program out there that would help me design and toubleshoot schematics I draw? For example, I have a schematic for a power supply that takes a 6.5k "core and coil" transformer and ups the voltage to 15k to supply a Van de Graaff generator. Now, the problem...
  16. Y

    Clarification on calculating Electrical Force and charge

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  17. N

    Definition of electrical branch

    Hi everyone! I wanted to know why in the circuit analysis a generator doesn't represent an electrical branch? And the second question is if two resistors are in series on a wire, does it represents only a branch(the series of the resistance) or two branches ?
  18. P

    RF Signals - Radio waves or electrical signals?

    Hi all Sorry if this is quite a basic concept, but I am confused about RF signals. The way I currently understand it is that radio waves in space are an oscillating electric and magnetic field at 90 degrees to each other traveling through a medium. However, when you pass a radio wave into a...
  19. M

    Engineering Electrical or Electronics Engineer career queries

    Hello, I would like to hear from people who have first hand working experience(have been employed) what are they doing(a typical day in the office) on the following fields: a)Systems Engineering b)Embedded systems Engineer c)Robotics,systems and control d)analogue and/or digital design...
  20. D

    Engineering Boolean circuit electrical engg 2nd year

    hi everyone i have a lab due tomorrow and wondering if someone can help me with question b. See attachment. I have done the k graph and got my boolean equation c'd+bd+b'cd'+ab'd. i just simply can't make the circuit. i have to use only and or gates. can someone please help Not sure if you can...
  21. C

    Understanding Electrical Potential and potential difference.

    Hi, I'm trying to understand electrical potential and potential difference. I was wondering if anyone can confirm if what I have written is correct or not? If not I would be glad to learn what I am yet not understanding. When you push away an electron of negative charge from a positive...
  22. P

    Question regarding electrical potential energy required to assemble a system

    Homework Statement Four charges, q1=+q, q2=-q, q3=+q and q4=*q are at the corners of a square with the side a=7.5 cm. (In such way that if one travels along the perimeter of the square, the charge signs are alternating.) If q=3.0 μC, what is the total energy required to assemble this system of...
  23. S

    Electrical Force Between Two Moving Charges

    We all know the coulomb's law of electrical force between two charges q_1,q_2 equals to \normalsize F= Kq_1q_2/d^2. But this law is not precisely true when the two charges are moving. We know for a single charge q moving with a velocity v the force is \ F=q(E+v×B) What is the straightforward...
  24. Y

    Electrical eng, my vectors for KVL and KCL aren't adding up - no errors in math

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  25. Q

    Engineering Use KCL to solve a Very simple electrical circuit

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  26. R

    Engineering Antimatter Engines and Electrical Engineering?

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  27. X

    Engineering Most useful parts of electrical engineering?

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  28. I

    Engineering Circuit Problem electrical engineering

    Homework Statement Here's the question: http://puu.sh/171ls The Attempt at a Solution I have no idea where to begin. It says R(AB) = R(L) = 301 ohms. What does that mean? Does R(AB) mean the resistance from A to B? Is that the total resistance? The total resistance is equal to 301 ohms which...
  29. S

    Electrical Engineering: Calculate the fault level for a 3Ø fault

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  30. B

    Skin Effect in Electromagnetism: Detailed Explanation

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  31. J

    Engineering Designing a Multi-Setting Stove Using Resistive Heating

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  32. Crazymechanic

    How can I safely separate mains phase for electricity transfer?

    Hi I am thinking of ways how to transfer electricity so that I can separate the phase magnetically or otherwise, Ok we all know transformer is one way to do it but it's big with mains frequency, other would be pulsed DC in an smps , but that's is already a very tried idea, is there any other way...
  33. M

    Engineering Print a circuit for measuring electrical impedance

    Hi there, I am supposed to measure the electrical impedance (which depends on conductivity) of an electrically conducting object by use of eddy current technique induced by an air core coil. for this purpose I need to print a circuit. would you please help me with the characteristics and out...
  34. K

    Calculating Voltage Gain for Electrical Circuits: A Step-by-Step Guide

    Homework Statement I've been reviewing my electrical theory and I'm having trouble trying to calculate an expression for the voltage gain for these two specific circuits. (Images c and d of the question.png attachment). I already know the answers, however I am unable to derive the same...
  35. T

    Engineering Need help with a really basic electrical circuit(KCL, KVL, Ohm's law)

    Homework Statement I should find i1 and i2. Homework Equations V = R*I KCL KVL The Attempt at a Solution I have no idea where to even start, so I tried doing different things, but nothing that I do works. I am just really frustrated right now, for failing at doing such a simple thing. I...
  36. M

    How does electrical energy perform work?

    Sorry if the title is slightly misleading, but I'm having a hard time trying to develop a better understanding of electric current and electrical energy. Basically, I understand that, say for example, a potential difference across a circuit creates an electric field, which in turn causes the...
  37. L

    Finding θ That Balances the Electrical Forces

    Homework Statement Figure 21-34 shows electrons 1 and 2 on an x axis and charged ions 3 and 4 of identical charge q and at identical angles θ. Electron 2 is free to move; the other three particles are fixed in place at horizontal distances R from electron 2 and are intended to hold...
  38. S

    More math for electrical engineering student

    Hi, I have finished my bachelors in electrical engineering and now I will continue with masters in the same area, specifically in telecommunications/signal processing branch. I would not consider my mathematical background too weak, I have good knowledge of calculus and linear algebra. In the...
  39. J

    Best route for electrical engineer

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  40. A

    Equation For Electrical Production

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  41. D

    Electrician to Electrical Engineer

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  42. G

    EMF expression in electrical generator

    Hi all! I'm studying electrical generators, and while I was trying to come up to the expression of EMF induced in a conductor I got two different results following two different ways, and I can't find the error. With sinusoidal B, with e=bvl I get an RMS value E=2K_{f}f\phi, while with...
  43. J

    Electrical and magnetic fields are spherical right?

    When i think of electromagnetic waves i think of a fast moving sphere of expanding or contracting fields,either magnetic or electrical depending on where its at in its cycle. So i guess I am picturing a single photon as a sphere. Is this a correct visualization?(i doubt it). If so, how does a...
  44. S

    Schools Graduate School Electrical Engineering with a BS in Math

    My long range educational goal is to complete a PhD program in Electrical Engineering. I am currently enrolled in a dual degree program to get a BS in Math completed in the Spring and my BS in EE completed in the Fall of 2013. There is a specific federal engineering job I was interested in...
  45. W

    Need help from Electrical Engineers Please (CFC60 and CFC36 reqs)

    Hello everyone, I am needed to apply a filter to some acceleration data. That I think I can handle (I have chosen a Butterworth). What I do not understand are the CFC (Channel Filter Class) specifications. In particular, I do not know what a "Stop Damping" number specified in -dB is...
  46. M

    Engineering Just got my Electrical engineering degree in Canada - what to do next

    Hi, I just graduated from electrical engineering from University of Toronto. I am interested in Hardware and robotics mostly. Most of the courses I took are in Analog and digital hardware and a little bit of power. I was wondering about job perspective in Western Canada where the jobs have...
  47. T

    Engineering Electrical Engineering - Where are the fast paced jobs?

    This is my first post! Just found this forum - and I'm diggin it... A little background: I'm 30 living in Denver, CO. I have worked in aerospace since my senior year of high school. I was brought on at my current company (large aerospace company) as a 'analog design engineer' which is...
  48. H

    Calculating the thermodynamic efficency of an electrical energy power station

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  49. D

    Engineering Do Electrical Engineers have to be good programmers?

    Hi guys, I've finished my first year of general engineering, in which I learned how to use MATLAB. I wasn't very good at it and only received a B. This leads me to believe that I won't be able to program very well and thus, won't succeed at courses offered in Electrical Engineering. Is this...
  50. O

    Grad Dip in Science (Physics) for an Electrical Engineer?

    I graduated with degrees in Electrical Engineering and Commerce from a good-ranking Australian university in 2010. I've been in the workforce for 18 months – found it to be not nearly as stimulating as the uni environment, so I'm contemplating the possibility of pursuing a masters or PhD...
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