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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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Is my simplified explanation of Volts vs Current correct? [closed]

I was struggling to find any meaningful difference between Volts and Current, when studying the basics of Ohm's law. The sentences explaining Potential Difference, between the negative and positive ...
securityauditor's user avatar
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Can field effect transistor s channel s varying depletion layers generate electric flux and control output current indirectly

Since magnetic field lines without need of contact attracts iron filing and drag them closer so that magnetic field line remain smallest.same analogy applied to field effect transistor ions in the ...
Phoenix Bird Eduventures's user avatar
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How is a steady current maintained in case of motional EMF if net force on electrons is zero?

I looked at the derivation of emf induced in case of a conducting rod entering a uniform magnetic field perpendicular to it, emf$=Bvl$ if $B$ is the strength of magnetic field, $v$ and $l$ are ...
Arush Desai's user avatar
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Force on current carrying loop due to non-uniform magnetic field

I was been taught that when there is a non-uniform magnetic field then the Force on a current carrying loop with Magnetic Moment M is F = M(dB/dx) where B is magnetic field. I can't get hold of this ...
Navanieeth TS's user avatar
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Force acting on an infinite wire with current inside a magnetic medium

I've recently stumbled on an electromagnetics problem that I don't quite understand. There is an infinite wire carrying current I that is placed inside a medium with magnetic permittivity μ1. At a ...
Zuzia Woźniak's user avatar
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Is there any specific terminology for this type of current in spintronics?

In spintronics, there are several types of currents: Spin-polarized current: The two spins flow in the same direction with unequal contributions. Perfectly spin-polarized current: Only one species of ...
Isaac Wang's user avatar
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Why do lamps in circuit have potential difference but two points in cable without anything in the middle of it have no potential difference?

I'm preparing for my EE major, this is my starting point.
Raudana Muntazar's user avatar
1 vote
3 answers
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Visualization of resistance [closed]

What does a resistor do in an electrical circuit? Does it impede the flow of electrons by increasing offering a path that offers a large no. of collisions? How can i visualise it, i have been told to ...
Anton Bert's user avatar
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2 answers
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Current loop and electromagnetic energy

Take a fixed circular loop of wire in a uniform magnetic field. As far as I can tell, the work we have to do to accelerate the electrons in the wire so a particular current is attained is independent ...
Ted Burgess's user avatar
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2 answers
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Growth of Current in an Inductor Connected Across a Battery [duplicate]

When baterry is connected across inductor with no resistance in circuit, won't the current flowing through it be zero, as inductor back emf will counteract the effect of potential difference due to ...
Tanay Sehgal's user avatar
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2 answers
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Electric force is zero in a solenoid

This is a question from Young and Freedman's University Physics. The book's answer says that the electric forces are zero because the wire is electrically neutral, with as much positive charge as ...
nomadicmathematician's user avatar
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Potential difference when two emf sources are connected in a simple loop circuit

I am having difficulty understanding the equation below for the potential difference between the two terminals of an electromotive source when two sources are connected from Sear and Zemansky's ...
nomadicmathematician's user avatar
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Maximum voltage that a system of two capacitor withstands when connected in series [closed]

Question: A capacitor of capacitance 1 micro faraday withstands the maximum voltage 6kV while a capacitor of 2 micro faraday withstands the maximum voltage 4kV. What maximum voltage will the system ...
Navanieeth TS's user avatar
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Why is current the same when batteries are connected in series? [closed]

I struggle to understand why the current remains the same in the circuit when batteries are connected in series. Update I can reason with it if someone can confirm the update. If the speed of ...
DPV's user avatar
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Current flow on the edge dodecahedron [closed]

What is the method for solving this kind of problems? In this dodecahedron (30 edges) identical resistors are placed along all the edges. What is the current flowing through the edge AB?
Galaxy Inc's user avatar
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Can resistors having equal magnitudes of potential difference be considered to be in parallel?

More specifically, if potential difference across a resistor, is exactly negative of the potential difference across another resistor, can they be considered to be in parallel? If so, why? Can the ...
Bongo Man's user avatar
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In an infinite square grid of resistors, why isn't current distributed equally at adjacent node of current injection?

Consider an infinite square grid of resistors, where a current of magnitude $i$ is injected at a particular node, and withdrawn at infinity. At that node, the current would split equally in the four ...
brainfreeze's user avatar
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Does all the Energy provided by the battery dissipate into heat?

Before proceeding onwards please note that I am talking about a simple circuit consisting of an ideal battery, a switch and an external resistance. So I was told that $$ W_\text {ideal battery} = Q_\...
Gauransh's user avatar
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Is it safe to assume it to be a balanced Wheatstone bridge?

If we calculate the potential at both ends of these $3\,\Omega$ and $4\,\Omega$ resistors, that comes out to be the same. It is $V/3$ at both ends of the $3\,\Omega$ resistor and $2V/3$ at both ends ...
Physics_enthus's user avatar
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Getting conserved current from electromagnetic field-strength tensor

The equation of motion that we get from the electromagnetic lagrangian is: $$ \partial _\mu ( F ^{\mu \nu}) + J ^\nu = 0 \tag{A} $$ Here $J$ is the conserved current that couples to the field $A_\mu$. ...
baba26's user avatar
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3 answers
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Do moving charges still generate an electrostatic field?

According to my EM professor, an infinite line of current $I$ creates only a magnetostatic field (the regular $\vec B=(\mu_0 I\vec /2\pi r)\vec e_\varphi$ you get from applying Ampère's law), and not ...
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The ratio of the energy of the electromagnetic wave produced by the flow of current to the energy of the current flow itself

How to determine the ratio of the energy of an electromagnetic wave produced by a current flow to the energy of the current flow itself? What conditions must we take into account? In general, it can ...
user1785960's user avatar
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2 answers
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How to find current direction from voltage value?

+2024.06.04. editted I'm adding an example image of the data I have. My circuit is a raster(matrix) format, and each cell (entry) is a node of the circuit. In the example, 1A is injected into the ...
Non's user avatar
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1 answer
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Do twisted pair wires create a helical shaped magnetic field if parallel electrical currents are run through the two wires?

I would like to know if the shape of the magnetic field around twisted pair insulated wires will be a helical shaped magnetic field if both wires have parallel electrical current running through them. ...
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Conservative and non-conservative electric field due to to changing magnetic flux

Consider this situation in which a uniform cross section conducting neutral ring is placed in a changing magnetic field which is given by $B=kt(-\hat{k})$ ($k$ is a constant and $t$ is time). The ...
FUSION X's user avatar
2 votes
3 answers
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Current density and units

I have a question about current densities. My understanding is that there are 3, volumic $(\vec{J})$ , surface $(\vec{K})$ and linear $(\vec{\lambda})$. The first question is, that if J is volumetric, ...
JL14's user avatar
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1 answer
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Why does the stopping potential correspond to zero current?

My textbook has derived an equation for the stopping potential during the photoelectric experiment as follows: $$\frac{1}{2}mv_\text{max}^2=eV_0 \\ \implies V_0=\frac{mv^2_\text{max}}{2e}\implies V_0=\...
Schrödinger's Cat's user avatar
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3 answers
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Can an inductor increase circuit current?

Suppose there is a simple circuit with a resistor, battery and inductor. The question that came to me is, by opening the circuit breaker, can the inductor be used to oppose and slow down the circuit ...
Parsa Yasini's user avatar
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2 answers
127 views

What is the area of a resistor?

I get confused every time in series and parallel questions. When two resistors are connected in series the area of combined resistors remains constant, and length gets doubled, while in parallel ...
pixie's user avatar
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2 answers
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Direct Current through a Copper Tube - Magnetic Field Question

Passing direct current through a straight copper wire generates the familiar "nested" cylinders of magnetic field strength along the length of the wire, decreasing in strength with distance. ...
GravityTim's user avatar
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General Form of the Biot-Savart Law for anywhere on the $x$-Axis [closed]

This question is beyond me, and I have very little direction for solving it. I understand that the component of $\ B $ perpendicular to the $x$-axis is 0, and that the component parallel along the $x$-...
5eamus's user avatar
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1 vote
1 answer
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Forces on an elliptical current-carrying Loop

Consider a current-carrying elliptical 1-turn coil as shown in the picture below: Is it true that due to forces from the current, the elliptical shape of the coil will tend to become circular?
Fan's user avatar
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I'm getting different values for the calculation of voltage drop across parallel resistors than I am for the summed voltage drop. How do I fix this?

I'm getting different values for the calculation of voltage drop across parallel resistors than I am for the summed voltage drop. How do I fix this? The current on the 4ohm resistor is 0.5Amperes. ...
HugeNerd's user avatar
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2 answers
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Zero Shunt Resistance in Ammeter

To reduce the resistance of ammeter, we attach a shunt resistance in parallel to the galvanometer. Also, this allows galvanometer to measure larger currents even though it has less value of the full ...
Anonymous's user avatar
1 vote
1 answer
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Confusion about EM waves in a conductor, AC in wires, and skin effect

I am trying to get my head around these different points: From Maxwell's equations we find that an electromagnetic wave in a conductor decays in amplitude with a characteristic length of about 1 cm in ...
user655870's user avatar
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4 answers
141 views

Will I get shocked touching the hot wire in these cases?

I have 2 questions in the situation if I stupidly touch the hot wire in a circuit: If the neutral wire is not grounded, then if I touch the hot wire, there is not return path from the hot wire, ...
InTheSearchForKnowledge's user avatar
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0 answers
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If someone moves with a velocity $v$, relative to a conductor carrying current $I$, will the current change with respect to the observer?

If someone moves with a velocity $v$, relative to a conductor carrying current $I$, will the current change with respect to the observer? I feel that the drift velocity of current is independent of ...
Maths lover's user avatar
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2 answers
72 views

Why is my voltmeter reading the supply voltage instead of load voltage?

I am very new to electronics and am a physics student working on an assignment. I have a very simple circuit set up in my bedroom: A power source of DC +0.7A and +5.0V with a single resistor of 100 ...
Gijahara's user avatar
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2 answers
29 views

RC discharging equation/natural response

Why do we make this particular assumption when trying to derive the capacitor discharging equation/rc natural response? If we don't and solve the equation just by assuming Ir=Ic, then the equation ...
Santhosh S's user avatar
4 votes
3 answers
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Unable to Understand How Current Divides in Parallel Circuits

for some context: I was self-studying and got confused about this question. This is a past paper question from the CAIE O Levels Board and its reference code is shown in the image attached below. I ...
Hamza's user avatar
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1 vote
1 answer
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Why does the phase difference of the capacitor voltage change with AC frequency?

In the graph below, the left vertical axis of the graph is the magnitude of voltage, the green line indicating the input voltage, blue line indicating the capacitor/inductor voltage. The right ...
Maxine's user avatar
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1 vote
1 answer
58 views

Why does current lag behind voltage by 90° in an inductive circuit?

We can easily prove this with KVL, a little bit calculus, and trigonometry. We get voltage as a sine function and current as a cosine function. Then we apply 'Add sugar to coffee' and get that current ...
Harjot Dhillon's user avatar
1 vote
1 answer
113 views

Derivation and theory for $I = kV^n$ [closed]

I performed an experiment in college to study the nature of a filament of a lamp, determine $k$ and $n$ in the relation mentioned, and study the variation of wattage of a lamp. I assume ohm's law is ...
DocAi's user avatar
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0 answers
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Will a charge be attracted to current carrying wire,

If we have current carrying wire(infinetly long) at potential 10V(say) in 2D space and a positive charge somewhere at a distance from wire(intially at rest). Will the charged particle be attracted to ...
SHINU_MADE's user avatar
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1 answer
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Which of these is the right way to interpret finding the current across a coil

If we have a coil which has a resistance of 100 ohms an induced emf of say 20V and this is connected to an AC power source of 100V and is in a series connection with another resistor of lets say 50 ...
hoff's user avatar
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0 votes
2 answers
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How is power dissipated proportion to current and current squared?

$P=IV$ and $P=I^2R$. Does this mean that $P$ is proportional to both $I$ and $I^2$? I don't understand this concept. And when should I use the various formulas for power? When another variable is ...
Mathguy3829's user avatar
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3 answers
82 views

Why There's No Current Flowing in This Part of The Circuit?

One time, in my Physic Class my professor ask us, "How much current is flowing in this circuit?" and everyone answer $5$ Ampere (Because, it looks like the resistor is arrange in the series ...
aki's user avatar
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2 votes
2 answers
85 views

How could free electrons flow in a conductor? If electrons actually flow in a conductor, then won't the atoms of the conductor become unstable?

I've read in many physics books that electrons flow due to a potential difference across a conductor, and that the flow of electrons is opposite to the current direction. But, if electrons move from ...
Doodieman360's user avatar
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1 answer
54 views

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
1 vote
1 answer
44 views

How would having a non-ideal ammeter affect the resistance across this bulb?

A non-ideal ammeter is one that has resistance right. So that means that work will be done by the current flowing through the ammeter and there will be a potential difference across it. This will then ...
3lsef's user avatar
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