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Questions tagged [electricity]

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

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3answers
617 views
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How could lightning have killed 322 reindeer at one time in Norway?

Lightning is supposed to have killed 322 reindeer within an area that's about 50-80 meters in diameter on a mountain plateau in Norway. Nearly the entire herd died. Sources: (1, 2, 3, 4) Photo: ...
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0answers
31 views

Which weight would be necessary to power a computer with this system? [on hold]

Let's say I install such a system: in a corner of my room, that produces energy in a similar way than grandmother clocks, connected to an alternator (or any other system that transforms mechanical ...
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1answer
17 views

Does potential difference depend on the size of an object

Let's say object A has received a number x of electrons and is now at a 1v higher potential relative to a neutral ground. Now if object B which is 2 times bigger than object A receives the same ...
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2answers
171 views

Why doesn't the electric potential constantly decrease in a circuit as the current moves from the positive to the negative terminal?

Why doesn't the electric potential constantly decrease in a circuit as the current moves from the positive to the negative terminal? Details and Assumptions: 1. The wires show no resistance.
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Tesla Coils and Fluorescent tubes

I was recently at the Nikola Tesla Museum in Serbia. I found it a bit lacking on the science aspects of Mr Tesla - but it held a remarkable collection of his personal belongings (he was evidentially ...
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2answers
330 views

Forces on charges moving through battery

In the attachment, which comes from a text "Introduction to Electrodynamics" by Griffiths. There are two statements: "Within an ideal source of emf (resistenceless battery), the net force on the ...
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1answer
19 views

What are simple comparisons of energy draws? [on hold]

I have recently attended a Bitcoin mining conference. Some of the attendees were specialists in energy with their business being oriented around building data centres or catering to the needs of data ...
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7answers
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What causes an electric shock - Current or Voltage?

Though voltage and current are two interdependent physical quantity, I would like to know what gives more "shock" to a person - Voltage or Current? In simple words, will it cause more "electric - ...
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1answer
273 views

Is wearing an insulated metal armor against a lightning safe?

Related: Is wearing metal armor during lightning safe? only partially answer my question. During a discussion in my question in Worldbuilding, this answer explain that as long as the metal armor is ...
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0answers
19 views

Need Help with Proving Faraday's Law of Electromagnetic Induction with Experiment Results [on hold]

I have recently conducted an experiment measuring emf over time and magnetic field strength over time as a bar magnet fell through a coil. The magnetic field was measured by pointing a magnetometer to ...
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1answer
35 views

Current densities in a 3D object

What is a smart way to calculate current densities in 3D objects with unorthodox boundary conditions? For example, J(x,y,z) in a cube with constant resistivity with applied voltages Va in a vertex ...
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0answers
47 views

Electricity cost of a kettle [closed]

A 2.5kW electric kettle has an efficiency of 95%. (95% of the electrical energy supplied is converted to heat in the water.) Electricity is charged at 22 cents per kWh. How much money would the ...
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1answer
24 views

How does 'conservation of law of energy' work in an open circuit connected to a hydroelectric generator?

I am trying to relearn high school physics and having trouble visualizing electricity in an 'open' circuit. I am going to use layman terms so i don't confuse myself! Apologies in advance if i am ...
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2answers
197 views

How does Lenz law conserve energy in this case?

A magnet is falling into the coil as shown. The current in the coil creates a magnet as shown ( by the right-hand grip rule ). Now, as the magnet falls towards the coil, the magnetic field strength in ...
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1answer
21 views

Electric power correction

The electrical energy is defined as: $$ E(t) = Q(t)V(t)$$ The general definition of power: $$P(t)=\frac{dE(t)}{dt}$$ and becomes $$P(t) = \frac{dQ(t)}{dt}V(t) + \frac{dV(t)}{dt}Q(t) = I(t)V(t) + \...
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44 views

Resistance and electricity

strong text In the answer to this question, it stated that the current would remain unchanged and I was wondering why the current would remain the same for the portion of the wire even though the ...
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1answer
31 views

Electromagnetic Induction - An Experiment

I am currently working on a personal project where I am investigating Electromagnetic Induction. My set up includes two loops - one primary and one secondary. The primary loop is hooked up to a ...
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2answers
56 views

Could you transmit electricity wirelessly?

Since you can wiggle an electron to get a radio wave And if you 'wiggle' it fast enough you get higher and higher frequency right? So couldn't you just broadcast an electromagnetic beam or whatever ...
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1answer
160 views

Do the electrons arrive at the anode with some kinetic energy? Where does it go?

I'm studying electronics and circuits. I'm trying to understand how electrons behave as they move in a circuit, but there's something that still bothers me. Electrons have some potential energy (the ...
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4answers
99 views

Frequency of light versus frequency of electron vibration

I've been trying to understand photons and light, although entirely conceptually (layman with not much of a background here, but I really want to understand this a bit better) and there's a couple of ...
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1answer
168 views

Electrical charge equilibrium and the piezoelectric effect

About the piezoelectric effect: if I press a crystal the electrical charges segregate and an electrical voltage appears on the other two faces of the crystal. See this link for example: http://www....
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1answer
326 views

Confusion regarding Hall effect in semiconductors

In many places, it's mentioned that in hall effect, the holes move under the influence of magnetic field in the direction as shown in the figure. In this figure itself, the bound electrons move in the ...
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1answer
230 views

What is vacuum to DC flow?

I know how an air gap behaves: for lower voltages the resistance is extremely high, until spark voltage is achieved, at which point resistance rapidly drops, creating electric arc. Now, how does that ...
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0answers
11 views

Planck's Constant to the Kibble Balance

A tad confused on how the Kibble balance actually relates to the Planck Constant. There's most likely a very simple relationship that I'm missing (I feel this is a stupid question ..) If the Kibble ...
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4answers
12k views

What is the difference between conventional current and electronic current?

what is the difference between conventional current and electronic current? How are they linked to one another?
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2answers
166 views

Potential difference in a nonuniform electric field

Let's say I have two points in a nonuniform electric field and those points have the electric potential 10 V and 5 V. If I then would use a voltmeter to determine the voltage between those points ...
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1answer
157 views

General Question about Faraday Disk and a Loop

If we have a constant magnetic field, $B$, perpendicular to a rotating metal disk (essentially Faradays's disk), with some angular frequency, $f$ . Then there will be an emf across the ends of the ...
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1answer
315 views

Numeric value of the electrons drift velocity in superconductors

Somebody knows the numeric value of electrons drift velocity in superconductors? How this value depends from the used superconductor material? What's about the current? Since the electrical resistance ...
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2answers
465 views

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

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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2answers
843 views

charges on sphere

When charges are released on sphere, what is the shape made by charges? Two charges are on opposite points of one diameter of the sphere. Three charges make a shape of an equilateral triangle. ...
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11answers
41k views

Why is the charge naming convention wrong?

I recently came to know about the Conventional Current vs. Electron Flow issue. Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and ...
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2answers
222 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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5answers
848 views

Why does more rapidly changing magnetic field induce greater EMF?

I am confused about the above question. I know that when you move a magnet in and out of a close loop of wire, you induce a EMF in the wire. The change of moving the wire in a out of a wire is what is ...
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3answers
4k views

Meaning of negative density

Charge density depends on the area/volume and the amount of charge. Before electromagnetism I used to think of density as being positive only. What is the intuitive meaning of negative density? Does ...
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2answers
332 views

Where are the electrons of a cathode ray tube coming from when using AC?

I see in this picture a beam of electrons leaving the cathode. But I read before, that the electrons can flow out of a copper wire only, if they are replaced by other electrons. I guess, that in the ...
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3answers
114 views

What's the explanation of 'paper pieces and comb experiment' about static electricity on atomic level?

I know that the charged comb induces static electricity in the paper pieces.how does that happen? Do the atoms in the paper get ionized,the same what happens when the comb was rubbed on hair?please ...
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4answers
230 views

Why do we use dielectric materials in a capacitor?

Okey first of I know dielectric materials used in capacitors to insulate and polarize due to electrical field created by two metal plates and then when you connect this stored energy to a system you ...
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1answer
295 views

Ohm's law and current due to magnetisation

I'm reading Landau's Electrodynamic of continuous media, specifically the following paragraph of section §29 (The magnetic field of a constant current): If a conductor carries a non-zero total ...
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4answers
49 views

Can a series of capacitors convey alternative current?

Since capacitors allow charges to pack on the negative plate, there is some current flowing for a short time. Also the dielectric does not prevent the EMF otherwise there would be no voltage at any ...
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6answers
9k views

What causes contact resistance?

When two components are combined in an electric circuit, there is apart from their own resistances a contact resistance at their junction. This causes a sudden voltage drop of $V_{drop}=R_{contact}I$....
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1answer
138 views

How to calculate total power generated?

I have a circuit with a piezoelectric transducer which converts mechanical energy to electrical. The ceramic is connected to a 1 Megaohm resistor and a voltmeter which reads voltage. If I want to ...
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0answers
15 views

Electrochemistry heat generation

In electrochemistry the Nernst equation says Gibbs=-nFE and the reversible heat=TdS= T*partialE partialT * -nF but the Bernardi heat equation is q= I(Voc-V+TpartialE partialT) when we know that the ...
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4answers
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Why the potential inside a solid conducting sphere is non zero while the electric field inside is zero?

I don't know why V is not zero inside the sphere. If we use the formula that V= $\int_{0}^{\infty}(kdq/r)$, how do we get that $V_{in}$ = kq/r?
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1answer
267 views

If we increase dimensions of a wire, how does electron density change?

If we increase the diameter of a wire, does the electron density change at all? When we increase the diameter or the length of a wire (while solving numericals) do we add appropriate number of ...
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2answers
30 views

Contradicting relation between total power consumed and power consumed by each individual resistor in series and parallel configuration

In a given series configuration of n resistances of equal resistance r, I derived the relation bewteen total power and individual power consumption as follows: P(Total) = I^2 * R R= nr (equivalent ...
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1answer
201 views

Why are some Air Gap Sparks Orange?

While testing the ignition system on my car with a variable gap spark tester I noticed that the spark was orange. I suspect that there may be a problem with the ignition coil such that there is ...
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2answers
34 views

Skin depth; EM wave and AC

When I google skin depth, I get the following definition, Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current ...
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0answers
29 views

Why can't we harness the energy of lightning? [duplicate]

Studying capacitors, this question struck me. If we know that there is a large potential difference between the ground and the atmosphere, why dont we use that to power our machinery? I understand ...
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3answers
5k views

Drift velocity of electrons in a conductor

How does the drift velocity of electrons in a conductor depend on the temperature? I have two contradicting views for this. First, we can say that increasing the temperature of the conductor will ...
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1answer
196 views

Spectrum of discharge of air

Where do the various colors in electrical discharge of air with a high voltage originate from? Are these transitions in ionized nitrogen gas or unionized gas? Are chemical reactions involved? I assume ...