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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How to calculate the current over $R_2$ with respect to time? [closed]

Five resistors, two inductors, two capacitors, a switch and three DC emf sources are connected together into a circuit, as shown in the diagram below. We are asked to develop an expression for the ...
John Stevens's user avatar
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Why does the force in a motor move perpendicularly instead of towards each other?

This may be a peculiar way of asking but given the image below: Flemings left-hand rule How does the wire experience a force upwards rather than being attracted directly to the magnet? If a current ...
Kjustin2024's user avatar
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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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Voltage/current direction of AC on circuit diagram?

Consider the following simple circuit consisting of an AC generator with voltage $V$ and a resistance $R$. As a result, current $I$ flows. Below the corresponding time-voltage diagram of the generator....
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Induced current in a superconductor

I was recently solving a problem from Jaan Kalda's handouts; Parallel to and at a distance $h$ above the surface of an infinite planar superconductor is an infinitely long straight wire with current $...
Cognoscenti's user avatar
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When the energy in a conductor is not carried by the electrons, how resistances warm up?

The energy flux in a conductor paints the picture that the "collisions" of the electrons with atoms (Drude Model) are not the reason for an resistance warming up in the presence of an ...
Niclas's user avatar
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How does this relation between DC current and Peak current arise? [closed]

I'm trying to understand the ripple effect in semiconductors and this formula was mentioned.
Mukesh Gopal's user avatar
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Why do we feel "bumps" when dragging your fingers over an appliance with faulty grounding?

Let us take a laptop which is plugged into a charger where the socket has faulty grounding. Now, when the charger is turned on and you drag your finger along the casing of the laptop, there is an ...
Alan Whitteaker'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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What happens when (XL-XC) of a series LCR circuit equals it's resistance during AC flow? [closed]

When XL equals XC, impedance Z becomes equal to R and the circuit is in resonance with the source frequency. But what would be the effect on impedance, phase power dissipated when R=XL-XC i.e. when ...
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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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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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Could you calculate the force between two NON-PARALLEL, straight current carrying wires?

Just like there are ways to solve for the force between two straight parallel wires, what is the way we could find the force between non-parallel wires?
linoloml's user avatar
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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 Petecki's user avatar
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Resistance in series also slows current down so why is resistance connected in parallel in galvanometer ammeter and not in series?

When we convert a galvanometer into an ammeter we connect the resistance in parallel, the only reason we connect a resistance in parallel with galvanometer is so less current passes and the flow of ...
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Determining the condcutivity of a material by method of contactless resistance caused by putting a sample rod in the inductor of an RLC circuit

I'm doing an experiment where I'm trying to determine the conductivity of a material by putting a sample rod in the center of a coil which is a part of an RLC circuit with an AC generator. I was told ...
Shxoenjci's user avatar
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Understanding radiation mechanism of inset fed microstrip antenna

I have designed a simple inset-fed microstrip antenna, resonating at 2.45 GHz. The transmission line model of the antenna reduces it to two radiating slots separated by a microstrip line, and it's ...
fraghotmailcom's user avatar
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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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Is there a way to quickly change the current in a superconducting loop?

In rocket designs such as VASIMR, superconducting nozzles are frequently used to focus the resulting plasma jet. This leaves out the question of TVC control mandatory in chemical rocket engines, and ...
Meatball Princess's user avatar
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1 answer
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Current and Magnetic Poles of a Solenoid (Diagram) & Right Hand Thumb Rule

Well, my doubt's pretty elementary. Firstly I wanted to confirm whether both the cases, as illustrated in the picture, are correct. I've darkened the part of each coil that faces us. Using the clock-...
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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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Applying Microscopic Form of Ohm's Law to Leaky Capacitor

When we write $j=\sigma E$ in a conductor, is $E$ here the net electric field produced by the electrons and the source that drives the current? For example, inside an electrolytic cell (let us assume ...
Cognoscenti's user avatar
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What is the electric field inside a perfect conductor connected to a DC source?

We all know from a course on electrostatics that the electric field inside a perfect conductor, placed inside a static electric field, is zero. Now imagine the same perfect conductor is connected to a ...
Solidification's user avatar
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Why force by electric field is appearing?

I want to ask about the Hall effect. Why is the force by the electric field appearing? I can understand the appearance of the Lorentz force. However, I do not know for what reason the force due to the ...
diana's user avatar
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Electricity: Ohm law vs Power in the Water analogy

I'm trying to understand electricity principles with the water analogy. I know this analogy is not perfect, but so far it has helped me the most. To recap: voltage (volt) is like water pressure ...
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What is meant by a source-free conductor?

I have recently worked with a source-free conducting slab filled with free space and with an electric field inside, and I have determined the corresponding magnetic field from MW's eq's. Next, I ...
Rasmus Andersen's user avatar
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Current electricity ( symmetric circuits) [duplicate]

I know this very well known problem. But the approach I am doing which I am explaining below. If we notice this diagram carefully I found the side part of A and side part of B cuts off and resistors ...
arnold's user avatar
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High voltage in transmission wires [duplicate]

My teacher asked a question and said to search about it. We know that the power consumption of the resistance (wasted power) can be obtained by the following formula: $$\begin{align} P &= I^2R \\ ...
BaRiboD's user avatar
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What is current density and is it a material property?

Current density has the units (Ampere/cm2) so by that is the total current flowing through a cross-section divided by the area of that cross-section. I'm working on developing a water electrolyzer ...
MJ392891's user avatar
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1 answer
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Purpose of potential difference in the presence of an electric field

Based on my understanding, charges are pushed along wires due to an electric field created by the battery, and charges gain electric energy as they loop through the battery. But I can't seem to ...
AscenderVI's user avatar
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What does the ammeter reading correspond to in a full-wave rectified DC supply

I was doing an experiment where I had to measure the current (using an analogue ammeter) from a DC supply. The DC supply actually provided a full-wave rectified current. I was wondering what the ...
user1070280's user avatar
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What is the difference between: “Electric Potential”, “Electric Potential Energy”, “Electric Potential Difference”, and lastly, “Voltage”? [duplicate]

Please provide very simple and specific examples/explanations when answering. Some have described Electric Potential as “work done per unit of charge”, but what exactly does “per unit of charge” mean? ...
Annikainen's user avatar
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How Do Dielectrics Affect Electric Potential Energy in Capcitors?

I am currently learning about dielectrics and capacitors in my physics class and part of what I have learned is conflicting. For starters the book says that capacitors do not interrupt current flow, ...
Julian Gutierrez's user avatar
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EMF generation by rotating rod without magnetic field [closed]

what is the EMF generated by a conducting rotating rod of mass $m$ and length $l$ in free space without magnetic field. the rod is roating with angular speed $w$? also find the current if the rod has ...
Konakalla Prajith reddy's user avatar
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3 answers
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Understanding Kirchhoff's first law in charged conductors

I wonder about Kirchhoff's first law in charged conductors. Consider: $$j = \sigma E \implies \nabla \cdot j = \sigma (\nabla \cdot E) = \frac{\sigma \rho}{\epsilon_0}$$ This means that Kirchhoff's ...
Niclas's user avatar
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Are the phases of the induced current (eddy currents) in a thin sheet uniform?

I have implemented a 2D finite difference method to compute the eddy currents induced by an AC magnetic field (homogeneous, oscillating at a fixed frequency) in a conductive thin sheet. Typically, the ...
tarta's user avatar
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Current density $J$ when θ = 90°

I've searched a lot on the internet, but so far, nothing has been able to resolve my doubt completely. So here it goes, We know that, $ I = \vec J • \vec A $ So, $ J = \frac {I}{Acosθ} $ Now, ...
Apogee Point's user avatar
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Why does current increase in step-down transformer?

I'm trying to make sense of transformers. $\varepsilon_{p} = $ emf in primary coil, $\varepsilon_{s} = $ induced emf in secondary coil, $N_{p} = $ number of turns in primary coil, $N_{s} = $ number of ...
Роман Кирьянов's user avatar
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1 answer
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Is power of a battery constant?

In my question I'm neglecting the impact of discharging. I'm trying to make sense of Watt's law: $$P=IV.$$ I always thought that the voltage and the power of a battery were constant features that ...
Роман Кирьянов's user avatar
5 votes
2 answers
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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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1 answer
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Why is the electric field the strongest inside the resistors?

My understanding is that current is constant throughout the circuit. So it means that in the areas with high resistivity or small cross-sectional area the drift speed on electrons is the highest. ...
Роман Кирьянов's user avatar
1 vote
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Does temperature cause electrons to vibrate more?

I read in textbooks that the mobility of electrons is affected by lattice scattering caused by vibrations of the lattice and by impurity scattering caused by impurities because they disturb the ...
Vladislav Gladkikh's user avatar
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Effect of a current-carrying infinite wire moving towards a stationary charge

An infinite wire carrying electrical current moving towards a stationary charge (perpendicular direction), why is there an electrical force on the charge in a direction parallel to the wire? I can ...
b wa's user avatar
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Electric current Lorentz transformation

What is the Lorentz transformation of the (scalar) electric current, $I$ ? I got two answers that are not consistent: Consider a lab frame where the charges are moving with a velocity $\vec{\beta}_q$, ...
Ahmad Haitham's user avatar
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Why is potential difference across resistor different than potential difference across a wire?

As far as I understand, the electric potential is the amount of energy that a third party agent has to spend to move a positive charge from infinite separation to a point. Thus, the electric potential ...
Роман Кирьянов's user avatar
3 votes
3 answers
419 views

Confusion about Circuits

I have two questions: When dealing with simple DC circuits, it is often said that the electrons in the wire move because the charge density of the surface charges decreases. Is that due to the fact ...
Blue2001's user avatar
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3 votes
2 answers
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What was defined first and how? The ampere or the vacuum permeability?

I've been looking up the history and evolution of the seven base units and am currently checking out the ampere. What I've found is that 1A is defined as the current in a wire which would experience a ...
SpectraXCD's user avatar
2 votes
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How to separate electron and hole mobilities in a intrinsic semiconductor?

I read in textbooks that the electric conductivity of a semiconductor is $\sigma=q(n\mu_n+p\mu_p)$, where $q$ is an electron's charge, $n$ and $p$ are the concentrations of electrons and holes, $\mu_n$...
Vladislav Gladkikh's user avatar
1 vote
1 answer
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How does current work in this instance? [closed]

If current has two ways to flow in a single circuit, let’s say one path has a resistor of 5 Ohms and the other has no resistors whatsoever, will current still flow in both of the conductors? Can ...
airil luqman's user avatar
2 votes
3 answers
161 views

Birds on power lines two feet versus one

So I know a bird can stand on a power line without being electrocuted because there is no current going to the ground. However, I know that curents will pass to different electric potentials. My ...
Mikayla 's user avatar

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