Questions tagged [electricity]
The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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' ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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_{...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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? ...
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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 =...
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