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# Questions tagged [electric-current]

A measure of the rate at which electric charge is transported (especially through a circuit), it has units of charge/time.

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### Wheatstone bridge circuit diagram [duplicate]

How can we draw any Wheatstone bridge circuit from a given circuit
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### Galactic Birkeland currents

Does Milky Way or any other galaxy produce Birkeland currents such as seen on Earth in auroras? If yes, how strong would they be?
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### Nickel plated steel strip for li-ion Battery pack - Purpose of Nickel Plating?

I am trying to build a battery pack from 18650 batteries, each interconnection is made from steel strip, most '18650 strip' has a steel core with nickel plating. I have a question regarding the ...
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### How is the voltage in this parallel circuit different across each component?

I'm studying up on circuit calculations and came across this circuit: I was taught that voltage in a parallel circuit is the same across all components, which would be the voltage supplied by the ...
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### Is the current same everywhere in a series circuit?

When we say that the current flowing in a series circuit is the same, do we mean that the current is sane in the entire circuit i.e, charge per unit time is the same in the entire circuit at any point ...
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### What is the use of resistors connected in series? [on hold]

If the current in a series circuit remains the same, then what is the use of a resistor? I read somewhere that as electrons flow through a circuit, they are accelerated towards the positive terminal, ...
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### Current Density In a 3D Loop - Discretising a Model

I'm working on a finite element model as part of a line of research. Specifically I'm consider using vector finite elements (i.e 3 values x,y,z per node) to solve the Poisson equation in magneto-...
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### Can we say $i=i_{0}\lvert\sin(\omega t+ \phi) \rvert$ is alternating current?

$$i=i_{0}\lvert\sin(\omega t+ \phi) \rvert$$ $i_{0}>0$. Can we say that the current described by the above equation is an alternating current? $$i=i_{0}\sin(\omega t+ \phi)$$ We are mostly ...
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### Why aren't salt water batteries used to power cars instead of lithium-ion?

I know salt water batteries are less efficient than lithium-ion, but water is safer, can be found anywhere, is cheap and 100% ecological. Even if it doesn't last long, you can refill anywhere. Why can'...
33 views

### In current flow, do electrons propagate simultaneously or one after another?

If we have 2 atoms (atom 'A', atom 'B') each with their own electron (A: 'Ea', B: 'Eb'): When Ea jumps from A -> B, simultaneously, is Eb in the process of jumping from B -> 'C'? or does Eb only ...
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### DC Motor: Split rings vs commutator [closed]

Question: In a simple DC motor (as shown below), explain the effect that replacing the commutator with slip rings would have on the operation of the motor, if no other change was made? My Attempt: I ...
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### Kirchoff law of circuit confusing me

I have read that kirchoff first and second rule is in accordance to law of conservation of charge and energy respectively.But I cannot relate how it does justify.KCL just states that incoming current ...
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### Vector potential, magnetic field and dipole moment due to a rotating cylinder

I've been struggling with the following problem: Consider a cylinder with height h and radius a with a homogeneous surface charge density $\sigma$ rotating about its symmetry axis with constant ...
44 views

### Current and Electricity

Is it possible that a current flows across a resistor although there exists no difference? If yes than how? Is this not a contradiction of ohms Law?
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### Are the electric flux lines between the fixed nucleus and the moving free electrons in the wire cut when an electric current flows in that wire?

According to the displacement current theory, An electric flux variation around the wire is "I" when an electric current in that wire is "I". Please, check the following paper and equation (18) ...
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### Relation between AC Current and electromagnetic wave in transmission lines?

I m so confused we started by learning about electromagnetic waves in the vacuum , then we went to transmission lines and there the professor mentioned the em waves are traveling through them. I ...
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### Can any other thing rather than current pass through conductor? [closed]

A conductor is an object or type of material that allows the flow of charge (electrical current) in one or more directions. Materials made of metal are common electrical conductors. Electrical current ...
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### Meaning of negative emf in the context of Kirchhoff’s Voltage Law

I’m wondering what it means when the emf of a battery is calculated to be a negative value through Kirchhoff’s Voltage Law. This is the problem: As you can see, we’re given the currents, and we can ...
58 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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### Some confusion regarding RLC circuits

I'm a mathematics student, and it has been years since I last did current/voltage/resistor related subjects in high school. However, for one problem that I've encountered, I actually need to calculate ...
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### In a simple resistor circuit, does the current reach V/R instantaneously?

Essentially, if I were to plot current against time for a simple circuit with a DC cell and a resistor in it, would there be a non-flat profile from time $t = 0$. So, between $t = 0$ and $t = t_1$, ...
150 views

### Stumped on understanding a Feynman lecture about force from wire on magnet

I must (sheepishly) admit that I'm stumped on a beginning page of The Feynman Lectures Volume 2. I have included a picture from the page. [Let me know if I'm breaking copyright, or if I can include ...
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### What does it mean by an AC of Infinite frequency?

For an AC of infinite frequency, Time period= 1/frequency = 1/$\infty\$ = 0 So, this means the polarity of AC is 'reversed in every 0 seconds'? Can you clarify this phrase?
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### Relation derivation based on the definition of Current Density

The current density is defined as: $$\textbf{J} (\textbf{r},t) = \rho(\textbf{r},t) \cdot \textbf{v}(\textbf{r},t)$$ where $\rho (\textbf{r},t)$ and $\textbf{v}(\textbf{r},t)$ is the charge density ...
According to Ohm's law: $V=IR$. Therefore $V$ is directly proportional to $I$. Furthermore, $V=W/q$ and $q=IT$. Thus $V=W/IT$. Therefore $V$ is inversely proportional to $I$. How can $V$ be both ...