The study of the presence and flow of electric charge. Charges, currents, fields, potentials.

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What is voltage?

I am a little unclear on what voltage actually is and I am trying to find out what the physical cause for voltage is. Is it the speed of the electrons through the conductor or is it an excess of ...
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0answers
7 views

Intuitive definition of electromagnetic field

I am curious about the following: Checking about what is an EM field in wiki it says: An electromagnetic field (also EMF or EM field) is a physical field produced by electrically charged ...
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1answer
13 views

Number of electrons flowing in a circuit

Does the number of electrons flowing in a circuit get affected when we turn on the light? If yes or no, then why. Help please.
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0answers
12 views

What would happen if an N doped semiconductor is connected to voltage?

I've been trying to learn electronics alone, and recently stumbled upon transistors. To my understanding, transistors are like two PN junctions back to back, but with the P region very thin. This ...
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2answers
4k views

What is the difference between induced and motional emf?

At least from their names, it seems motional emf is induced, so what's the difference?
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1answer
2k views

Definition of Free Electrons and Mobile Charges?

Could someone please give me a good definition of the following electric terms? Despite what searching I have done, I have not come across a definition that I have found clear for me to understand: ...
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0answers
21 views

What makes B-field not be arbitrarily large very close to an electric conductor?

Assume an inifinitely long, straight thin electrical conductor with current I. It follows from Ampere's law that the B-field intensity is proportional to 1/r, where r is the distance from the ...
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0answers
14 views

How do you calculate the electric tension between two charged entities?

If: 1) you know the coordinates and individual charge(in coulombs) of each object and 2) voltage is the difference in electric potential energy between two nodes How do you calculate the voltage in ...
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0answers
16 views

The induced electric field of an infinite current carrying wire

I am given, without motivation, that the induced electric field from an infinite, straight, current carrying wire is parallel to the wire itself. $$ \vec{I} \times \vec{E}_{\text{induced}} = ...
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2answers
21 views

Does a switched on power socket consume electricity? [on hold]

Lets say I have a TV and a power socket but the TV switch is off however the socket switch is switched on, so will it consume electricity?
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0answers
26 views

water permittivity

I made a water sondе from one sided FR4. The plates are parallel, copper sides are counterclaims. The plates are $5\times 50$mm, spaced at $7.5$mm. The expected value of capacitance is ...
8
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1answer
462 views

Tesla coil arc in air - where is it going?

here is a picture of a Tesla coil with a discharge that seemingly terminates in the air. What completes the circuit at the end of the streamers?
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0answers
3 views

Water flow in salt solutions contemporary exposed to an electrical and constant magnetic field

When a permanent magnet is held motionless close to a salt solution which already has been exposed to an electrical field a flow in the water will be induced and can be detected by applying some ...
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0answers
20 views

Why can xenon gas stay ionised after the “trigger voltage” is removed?

From my understanding of a Xenon flash circuit, a storage capacitor and a trigger capacitor are charged up to about 240V (both with similar RC values, but less capacitance is needed for the trigger ...
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2answers
312 views

If we connect a block of p-type semiconductor only to a positive terminal, will it become positively charged?

Connect the positive terminal of a battery to a piece of p-doped semiconductor, say, silicon doped with boron. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes ...
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1answer
26 views

RF disturbances produced by transmission power lines

I need a book or paper that contains "the effects of transmission lines on the radio frequency transmission and disturbances". Could you help me find a useful textbook? Thank you
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3answers
505 views

Polarization vector of dielectric electrostatics

I know two laws for Polarization vector of a dielectric material $$\vec P = N q \vec{\Delta L}$$ Where $N$ is the number of dipoles per meter cube, $\vec{\Delta L}$ is the vector that represents the ...
2
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2answers
2k views

The electric field of a conductive sphere containing a charge - grounded vs not grounded

Let's suppose we have a sphere but unlike theoretical ones it'll have some thickness say $\Delta r$ and inner radius $R$. What I was wondering about is how will it behave if we place some charge $q$ ...
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0answers
2 views

What state is needed to model AC 3 phase induction motor?

Suppose I have a regular 3 phase 50hz AC squirrel cage motor of known design. If I wanted to make a model of this motor, would I need to know more than: Angle of rotor Angular velocity of rotor ...
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0answers
10 views

Connection of circuit breaker [on hold]

I just want to know where is the circuit breaker connected in an electric installation? Is it on the live or on the neutral line of the generator? And why?
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4answers
790 views

What is the difference between a circuit with a resistor and one without it in energy terms?

In Fundamentals of Physics (HRW), an equation is derived for the current in a circuit in terms of its emf and resistance by the 'Energy method'; that is, deriving $\epsilon = i \cdot r$ and saying ...
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0answers
29 views

What is ultimate AC frequency and phenomena related to it?

Just as in title. What is the top AC frequency physically possible to obtain? And are there (and if yes, what?) phenomena occuring only at large frequencies? I'm thinking about a metallic wire. I know ...
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2answers
42 views

Removal of heat from a closed system using electricity

I was thinking this morning about how heat could be removed from a system in such a way that it is stored for future use. My ideas are a form of thermo-electric system that converts heat into ...
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0answers
25 views

I need some clarification about my understanding of voltages and resistance

So I was reading through this question, and I think resolved my query about what voltage actually is. I don't understand what we really mean by voltage drop But I just want further clarification ...
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1answer
108 views

Microscopic fields inside a conductor

In a neutral conductor if we assume electrons as point charges, the electric field in the space between them cannot be identically zero. This microscopic field may be very weak. What if we were very ...
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2answers
158 views

How is a potential difference created between two points?

I would like to know how potential difference is created between two points?Is potential difference created by adding more electrons at one side?If that's the case how to add more electrons at one ...
4
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4answers
1k views

Are square wave really square or are they always relative approximations using harmonics

I'm studying the properties of waves through different mediums, and got hung up on this. Is a square wave always a sum of harmonics or can we produce a square wave by quickly changing voltage? Is ...
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1answer
799 views

Electric field from conductive to dielectric media

I am interested in the main difference between transitions from electric fields from Conductive to Conductive/ Dielectric to Dielectric and Dielectric/Conductive media. What are the boundary ...
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1answer
17 views

How does differing surface resistance in a parallel plate capacitor effect the field strength?

I have been trying to find out how using different conductive materials for each parallel plate for a parallel plate capacitor will effect the field strength. Meaning if one of the parallel plates ...
4
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2answers
3k views

How can a conductor be grounded yet there are induced charges on it?

A classic example for the method of images is the following, quoted from Griffiths's Introduction to Electrodynamics, page 121: Suppose a point charge $q$ is held a distance $d$ above an infinite ...
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1answer
30 views

When you smooth-en a surface at microscopic level, friction increases. Why?

When I was learning a chapter related to Static electricity, my teacher had mentioned that when you rub your comb with DRY hair specifically, static electricity is generated due to friction. Further ...
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1answer
38 views

Why do electrical storms cause metal objects to vibrate?

I am curious about the vibration of metal objects as a sign of an impending lightening strike. This is apparently a common occurrence; so much so that a quick google search will yield many pages ...
2
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1answer
115 views

Potential difference between Earth's surface and 2 meters above

Assuming Earth is a charged sphere of radius $R = 6400\times10^3$ m with uniform surface charge density $\sigma = -10^{-9}$ C/m2 and with $\epsilon_0 = 8.85\times10^{-12}$ F/m I find that ...
0
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2answers
108 views

An infinite value for an electric field?

Consider a system of point charges. To calculate the value of an electric field at a point, we consider the contribution of the electric field from all the charges at that point. Consider the ...
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1answer
35 views

Why do my fingertips spark when rubbing a blanket? [duplicate]

I was sleeping in the dark when I reached over for my blanket. It slipped out between my fingers and made a light spark. I repeated in different parts of the blanket at least ten times. I can't ...
5
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1answer
41 views

Levitating capacitor

As the title already says, I would like to make a large capacitor levitate. Before you dismiss this question please hear me out: In essence, this is intended to be a way to avoid the constrains of a ...
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0answers
27 views

Study electronic from (not so much) scratch [closed]

I am going to start my last year (5th) of physics. I have studied linear circuits during my 2nd, but not very good... then I did some courses about electronic, but sincerely I can affirm that I have ...
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0answers
21 views

Circuit solving my mesh analysis [closed]

Please help me solve this question to find I
3
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1answer
396 views

If I charge a battery using a much higher current, can it explode?

If I have a 12V 4Ah lead acid battery and use a battery charger that, let's say for example, can charge 10A, 50A, or 100A. If I theoretically turned it to 100A will the battery explode? I understand ...
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2answers
28 views

The source and sink phenomenological description of charge - how realistic is it?

I've heard over and over an electron described as a source of the electric field, but that is a misleading term. Source makes one thing of a tap, with a constant flow of something coming out of it. ...
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0answers
22 views

why do electric field is zero out side of depletion region? [closed]

Why do electric field is zero out side of depletion region? Please show electric field is zero out of depletion layer by means coulomb rule(zero bias).
2
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1answer
54 views

Determining potential in coaxial cylinders

If I have two conducting, coaxial cylinders as shown: The potential at the outer cylinder is = 0. And I apply a potential difference across both cylinders in the form $V_a - V_b = V_{ab}$, how can ...
0
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1answer
224 views

How is current produced in semiconductors or metals?

I think current is the movement of electrons through the wire or semiconductor, thus when I press the switch of the light bulb the electrons go from positive part to tungsten and light is produced. ...
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3answers
184 views

Ohm's law holds at constant temperature - what about Joule heating?

Ohm's law states that the resistance of a conductor is constant provided its physical conditions, such as temperature, remain constant. But what I'm thinking is that as you increase the voltage across ...
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2answers
39 views

Why do we get electric shocks when most structures are insulators?

Suppose I was standing in the sea, and touched an electric fence; I would receive an electric shock, because both my body and the sea are conductors, and create a path for the electricity to flow. The ...
0
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0answers
11 views

as applied to the Dirac delta homogeneous distribution in mantle of a cone [closed]

hello me a problem arises in applying the Dirac delta function in mantle of a cone with a view to seeking load distribution, this doubt is how to find Q so applicable to this type of distribution, ...
0
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2answers
41 views

Energy in conductors with $\vec{E}$-field

The question is deceptively simple. Suppose I have a uniform circular wire in which I have created the a E-field by some mean. We that without the source the electric field should not be there, so if ...
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2answers
80 views

Is that ground, wall conductive?

If i put my foot exposed to ground and put my finger to the USB power, i will be electrocuted. So the electron(s) from the USB power is passing over my hand, run to foot and go to ground ? As i might ...
0
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0answers
17 views

can I maintain the temperature of a metal by electrifying it

Let's say we have a metal that is exposed to high temperatures. This will increase the oscillation of its molecules. Is there a way by applying electrical current to it, to restrict these ...
0
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1answer
175 views

What happens to gas molecules after ionization?

I know that gas molecules conduct electricity after they get ionized but what will happen if we keep increasing the voltage even after ionization? Will it explode? If it will then how much energy ...