Questions tagged [electricity]

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

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If metals can’t sustain an electric field inside them (as their electrons move to cancel it out), how do they still conduct electricity?

I tried to understand by my own couldn't do so.
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Why is current through the short circuited wire not zero? [duplicate]

Why does current flow in a short circuited wire? I understand that it offers negligible resistance to the flow of charges, but two points on the short circuited wire will have the same potential, so ...
Thrissha Arcot's user avatar
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If there's magnetic field around current-carrying wire, why doesn't it always exist?

Motion is relative. If we say train is moving, it moves with respect to the Earth. If we are inside, it doesn't move from our point of view. Then, with respect to what object do we say that electrons ...
Mateusz Duraj's user avatar
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How much energy does a single lightning bolt from this Van De Graaff generator consume?

I recently visited the Boston Museum of Science and saw a show using their "world's largest air-insulated Van de Graaff generator." I was curious as to the actual energy output of the ...
nuggethead's user avatar
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Anode/cathode in an electrolytic capacitor during discharge?

Wikipedia says "an electrolytic capacitor is a capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer" (1, link). Elsewhere, wikipedia seems to ...
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Heating a Material with Negative temperature coefficient of resistance

TCR (Temperature Coefficient of Resistance): $R = R_0[1 + α(T - T₀)]$ Where: $R$ is the resistance at temperature $T$, $R_0$ is the resistance at a reference temperature $T_0$, $\alpha$ is the TCR of ...
Nguyen Khac Khanh Lam's user avatar
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I don't understand how current always chooses the path of least resistance [duplicate]

As the question states, I don't understand how Current always chooses the path of least resistance. How does it even "know" to pick that path For example, if we have a short circuit which ...
Saad's user avatar
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Modeling an Electrolyzer System

In this study, the authors provide an equation for operating cell voltage: $V_{cell} = V_{rev} + V_{act} + V_{ohm}$, the sum of the reversible overvoltage, the activation overvoltage and the ohmic ...
Lucien Jaccon's user avatar
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Why do charges exist in the first place?

Why do charges exist, how did they come into existence? (if any theories exist, then please explain them in somewhat detail) What would happen if charges never existed? Please explain the answers at ...
Adwit Kumar's user avatar
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How is electrostatic force 'lost' during conduction in these examples?

When you rub a glass rod against silk cloth, the glass rod becomes positively charged and the cloth becomes negatively charged. So they now can attract each other. However, after this 'attraction' ...
Mel's user avatar
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Why doesn't charge accumulate in a loop?

When learning about electromagnetism at my university, electricity flow is generally shown as a conductor with a high potential at one end and a low potential at the other and thus charges flowing ...
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Trouble understanding an example in electricity and magnetism by M.Purcell

I'm having trouble understating the following example in section 3.2 of electricity and magnetism by M.Purcell: In paragraph 2 of the solution, it states that "The combination of these charges ...
WilliamHarvey's user avatar
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Why are the formulae for the electric flux density and the magnetic flux density fundamentally different?

I've been delving a bit beyond just using what's typically given as the "electric field" and "magnetic field" in various problems, and finding out about the various more ...
Outis Nemo's user avatar
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What happens to the charge which enters the positive terminal of the battery in a circuit? [duplicate]

SO basically , I know that a battery creates potential difference or V in a circuit to flow, by doing work on the charge(electrons) . The motion of the charge(electrons) is from the -ve or negative ...
Shreyas's user avatar
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Is electric current actually the flow of electrical charge?

In my high school, the definition of electrical current is "the flow of charges" but I have seen a video about how electricity actually works and it seems to me that electrical current is ...
InTheSearchForKnowledge's user avatar
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Would this simple design function as an electromagnet?

I was thinking about electromagnets today and a thought popped up in my mind on what would be a very simple way to create an electromagnet. Although I have not built and tested it, I am pretty sure ...
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What is actually electric current? [closed]

Electric current is the rate of flow of charges (electrons) or the rate of flow of positive charge. Okay, I get it. But here's my question. The electron flows in the wire and then the current flows in ...
Moksh Singh Dangi's user avatar
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The inequality relation between the e.m.f. of two cells and the equivalent e.m.f

Consider two cells of e.m.f. $ε_1$ and $ε_2$ with internal resistances $r_1$ and $r_2$ respectively set up parallel to each other in a circuit as shown in the figure: Let the equivalent e.m.f. be $ε_{...
archthegreat's user avatar
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3 answers
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Electrical energy is $I^2Rt$, and heat dissipated is also $I^2Rt$?

My book says: Let a current $I$ be flowing through a conductor of resistance $R$ for a time $t$, when a source of potential difference $V$ is connected across its ends. Then, it proceeds to prove ...
D S's user avatar
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Does the position of the fuse affect whether the bulb or the fuse would blow first?

If I connect a fuse and a bulb in series with: fuse to the live and bulb to the neutral fuse to the neutral and bulb to the live During an overloading would this cause: the fuse to blow and ...
Dharmik Santhosh Raghav's user avatar
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Why should the heating coil of a heater have high resistance?

In my book, it is given: The resistivity of an alloy is generally higher than that of its constituent metals. Alloys do not oxidise (burn) readily at high temperatures. For this reason, they are ...
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Force on charge carriers in a simple circuit

Is it true that in a simple circuit where a simple conducting wire is connected to a battery, the force on each charge carrier is same in magnitude ? If yes, then can you explain how? I know that if ...
Hufaiza Hufaiza's user avatar
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2 answers
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Why does the power loss in transmission cable increase when resistance is increased?

In transmission cables, why does power loss increase when length of conductor is increased? According to the formulas V=IR and P=I²R, When we increase the length, the resistance increases, while the ...
Hufaiza Hufaiza's user avatar
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3 answers
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Current density of moving charge distribution - mobile charge density vs. "ordinary" charge density of the distribution?

in Introduction to Electrodynamics by David J. Griffiths I have latched upon this definition of current density vector $\mathbf{J}$ (Chapter 5, section 5.1.3, p. 220 in 4th edition) and I would ...
Tomasz P's user avatar
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2 answers
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Electric current density definition

I'm just wondering why the current density $J$ is always defined as the amount of electric current traveling per unit cross-section area $J = \frac{I}{S}$, and not per volume unit $J = \frac{I}{V}$ so ...
ArziousYi's user avatar
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How to compute the resistance of a nonuniform cylinder with varying resistivity?

The generally quoted formula foe resistance is \begin{equation} R = \rho \ell/A \end{equation} some special cases are easy to solve. For example the case where the current flowing along the z-axis and ...
wander95's user avatar
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Can a DC voltage excite a pure semiconductor (or insulator) from the valence band to the conduction band?

I have a question I am sticking around and can't find a satisfying answer. Say I have an intrinsic semidonductor at zero Kelvin (no electrons in conduction band). I apply a DC voltage across it. Can ...
MLSPhy's user avatar
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Do electrons move faster towards the end of a circuit?

As 1 coulomb electrons go through 1 volt of potential difference, they gain 1 joule of energy. So in s series circuit, do electrons move faster towards the end of the circuit where they went though a ...
Varshil MVH Pets's user avatar
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1 answer
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Does the proton do anything in a simple electric DC circuit? [closed]

Since the valence or free electrons and doing the flowing guided by electromagnetic field, what about the protons that are still stuck in the nucleus inside the wire, battery, resistor what have you ...
user6760's user avatar
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Can static electricity (charged balloon) attract any liquid other than water?

I know that a charged balloon can attract a stream of water, because it is a dipole. I am wondering if a charged balloon can attract any other liquid other than water? Does it have to be a dipole? ...
Carbon's user avatar
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How does the rise in temperature of fuse wire depend upon its radius?

The question could be understood as if we have two fuse wires one of current rating 1 A and one of current rating 8A then what should be the ratio of their radius? I tried the following: We know, $Q =...
Darshit Sharma's user avatar
5 votes
2 answers
128 views

What is the "closed circuit" of a bug swatter racket?

There are bug swatter racket that can kill fruit flies, mosquitos, or flies, if the insect touches the metal mesh. However, when I look at the construction of the device, the metal mesh is all one ...
Stefanie Gauss's user avatar
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Fuel Cell Operating Pressure

I have seen anecdotal testing of fuel cell stacks. Intended to demonstrate that their power output can be improved through the addition of a centrifugal blower. What are the limits associated with ...
Slartibartfast's user avatar
4 votes
2 answers
617 views

Flow of electrons in wire

If we apply potential difference through wire we know that there is an electric current which is the flow of electrons.I want to know how do electrons move do they move within wire like in the picture ...
f3rhd_'s user avatar
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3 votes
2 answers
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Static Shock and Cell Phone

Please be kind - have probably a silly question about static electricit, the type when you walk across a carpet and touch something and you get a spark/shock on your finger. Hoping someone here can ...
Chill43's user avatar
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Is the electric potential at the mid point between two equally oppositely charged plates zero

Is the electric potential at the mid point between two equally oppositely charged plates zero. granted between the plates there is uniform fields. and what would the resultant potential graph look ...
sciencetadium official's user avatar
2 votes
2 answers
56 views

Will a metal rod kept under very bright light for a huge amount of time, be able to conduct electricity?

I was just sitting when it came to me - will a metal rod that has been kept under bright light for a very long time, be able to conduct electricity? I was thinking that because of photoelectric effect,...
Adwit Kumar's user avatar
22 votes
4 answers
6k views

Why don’t nuclear reactors burn through most of their fuel before discarding it?

The question: Why don’t nuclear reactors use more of the fuel, eg, 50%, 80%, before discarding it? It looks like there is plenty of energy left, and uranium is expensive. Also, there would be an ...
11111's user avatar
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2 votes
1 answer
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What can cause a spot above my WiFi router's antenna? [closed]

Lately a weird dark spot has appeared right above the antenna of my wifi router. It wasn't there before. I have tried to wipe it and it got a little bit brighter but I don't think it's dust. My guess ...
Szil_K's user avatar
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1 answer
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Modeling electric discharge in a game [closed]

I am working on a game with a basis in physics, abstracted and simplified but with an attempt to preserve the core of real physics. For example, fire effects don't do direct damage, but generate heat. ...
paholg's user avatar
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Electrostatics (Waler Lewin's Lectures): Cat-fur, Nylon Jackets, and Charges

https://www.youtube.com/watch?v=x1-SibwIPM4&list=PLmPcD-wiF4EY2y3oHGsoqG6C1PBMkmJSQ Please consider the above video from 24:15-25-32. I would like to understand how the charge is being transferred ...
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Is there electric field inside the conductor in moving charges case?

Is there an electric field inside a conductor when steady current passes through it ? I have two conflicting notions here : I was watching this Electroboom video and at minute $14:00$ electroboom ...
Razz's user avatar
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How can one explain the small amplitude resonance before the onset of main resonance condition?

I was using a sonometer to verify the frequency of a.c. supply in the lab is 50 Hz. For this the equation I used is f=(1/4L) x Sq. root (T/m) I set tension T = 4.9 N by hanging 0.5kg mass mass per ...
Shinnaaan's user avatar
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6 answers
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Why is current defined as $dQ/dt$ even though it is not defined as the rate of 'change' of flow of charges?

I do not understand this definition. $dQ/dt$ represents the rate of CHANGE of charge flow at an instant even though current is defined as only the charge flow per unit time.
Dhyaneshwar's user avatar
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2 answers
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Would be possible to cover all the deserts with solar plates and satisfy the demand of electricity?

if we covered all the deserts with solar plates , would that be the solution to the energy crisis ? i mean put a solar plates in ALL the deserts of the earth to harvest all solar power
Jose Perez's user avatar
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1 answer
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Can Sagnac effect be observed in coiled, rotating electrical cables conducting electric signals?

Can Sagnac effect be observed in coiled, rotating electrical cables conducting electric signals, in a similar way to that observed in coiled, rotating optical fibers? And if so then who demonstrated ...
Jimski's user avatar
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In depth answer: Why do I see sparks when I remove synthetic clothes off my body?

I have combed through various sources on the internet and I don't have a definitive answer for the above question: The best that I can come think is the following: Because when I remove synthetic ...
S_M's user avatar
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Sea electricity problem

If salt water is a good conductor of electricity so does it mean if we put a very large voltage somewhere in the sea then person all across the world will experience some current and are there any ...
Sidheswara Sahoo's user avatar
1 vote
1 answer
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Is Faraday's cage described in electrostatic 100% insulated?

I apologies if my wording is bad or it is duplicate. I'm new to Electrostatics. During the topic of conductors & electric field I was introduced to Electrostatic Equilibrium state in which the ...
Prabhas Kumar's user avatar
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1 answer
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Why can't we calculate potential at a particular point due to an infinitely long thin wire with uniform positive linear charge density?

I read in theory that we cannot calculate at a particular point due to an infinitely long thin wire with uniform positive linear charge density. Instead we can only calculate the potential difference ...
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