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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71 views

Cells connected with reverse polarity in parallel

How exactly are the corresponding equations derived here?
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Capacitors charging, resistance much more?

I am overwhelmed by the amount of doubts i am having regarding this device (CORRECT ME WHEREVER I AM WRONG PLEASE) First things first if we connect a capacitor using two ideal wires (for each plate) ...
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A.C. through resistance

There is a topic in my physics book "A.C through resistance". And in this topic there is a sentence " the applied voltage has to overcome the drop in resistance I.e V=IR." What do ...
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Newton's 3rd Law Coil in Magnetic Field

When a current-carrying rectangular loop is placed in a magnetic field, the forces acting on either side of the loop which is perpendicular to the field provides a torque which rotates the loop. ...
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RMS value of Alternating values [duplicate]

What is a RMS value and what is the point of RMS value? Why do we calculate it? Please be concise and precise and kindly express it in layman terms.
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Voltage in Direct current [closed]

Why is voltage in direct current constant? And why does the voltage in A.C changing? Do we provide the voltage in that way?
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Can vacuum breakdown occur from a positively charged surface?

Against a sufficiently large voltage, resistance is futile. Although the vacuum is a very good insulator, electrical breakdown can occur even in a perfect vacuum in the presence of a very strong ...
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Right Hand Rule Help: Part 1

I thought I understood the right hand rule but I guess not. Here is how I learned it in regards to finding the direction of the magnetic field vector of a current carrying wire. Point your thumb in ...
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Why is current in a circuit constant if there is a constant electric field?

I'm a beginner in E&M, and have just started to learn about current and Ohm's law. According to this page there is a constant electric field everywhere in a DC circuit pointing against the ...
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Circuit (Pseudo-Homeworks)

I'm studying Kirchoff's Laws and how to find $\Delta V$ between two points in a circuit (CC). I already know how to use it but I look on internet for more exercise to learn more and find this circuit ...
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Is Kirchoff's first law based on the probability that a current splits at a junction and goes either way?

I know that Kirchoff's law comes from the fact that charge is conserved at every junction of a circuit. But is it useful (and true) to think about this in terms of probabilities? As in, the ...
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In an intrinsic semiconductor, are there the same number of carrier electrons and holes? Or this is just exclusive for silicon?

I am working with some polymers that behave like semiconductors when they are plugged into the current. I am calculating the mobility of these polymers and I need the value of the current density (J) ...
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Completeness of Maxwell's equations

If we consider Maxwell's equations in the form: $\nabla\cdot\overrightarrow{E}=\frac{\rho}{\epsilon_0}$$\nabla\cdot\overrightarrow{B}=0$$\nabla\times\overrightarrow{E}=-\frac{\partial\overrightarrow{B}...
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Do electrons literally travel in order to change the charge of a substance?

Do valence electrons literally break free of their bonds and jump from substance(1) to substance(2) in case of charging by conduction? If so, how? Do these electrons remain suspended amongst other ...
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Electric current and motion of electrons

When a battery provides energy to an electric circuit, the electrons get aligned so as to transfer energy from the negative terminal to the positive terminal. The drift velocity of the electrons in a ...
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What is the Difference Between the Energy Current (Waves) and the Electric Current?

In Waves and Optics, my class has just been introduced to energy current. It is the flow of energy through a wire, yes? ... How exactly is this different from electricity (Electricity and Magnetism)? ...
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What are safe voltage differences to connect 2 batteries in parallel? [closed]

I have a OneWheel electric skateboard with a 58V LiFePO4 battery 130Wh (I believe 14s1p configuration). There is a method in practice where owners wire EGO LION battery packs (56v 2.5Ah=14s1p, 5Ah=...
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Does a moving charge create current?

If there is a moving charge, not in a circular path, but in a straight-line path, does it create current? If it does, what is the relation between charge ($Q$), Velocity ($v$) and current ($I$)?
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Does the direction of electric and magnetic field change in a circuit?

From my understanding, when studying a circuit, the magnetic field is either "in" the page or "out" the page according to whether the current flows clockwise or anticlockwise. So ...
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Electric current through gases

Gases are poor conductors of electricity due to the minimal amount of charged particles they have and also due to the regular recombination of ions of opposite polarity. However there are still ...
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A question on electric current

In my physics book the definition of current is If a charge $∆Q$ crosses an area in time $∆t$, we define the average electric current through the area during this time as $I=\frac{∆Q}{∆t}$. The ...
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How to find Currents based on mesh analysis?

Can anyone explain or give an example as to how to solve these three currents? I have tried very hard, but I keep getting stuck and obtaining the wrong answers.
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How to find Voltage based on reference nodes? [closed]

Here, $V_{ab}$ indicates the voltage referenced from node $b$ to node $a$. In other words, imagine $V_{ab}$ being identified in the diagram as having a "$-$" at node $b$ and a "$+$"...
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Can someone explain, in clear terms (not unmathematical) what short circuit is? [closed]

I don't get the idea about what short circuit is. In a few questions I have come across, it appears to be a short circuit but the answers say otherwise. In fact, I don't have a conceptual ...
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What happens when the length of the uniform wire is more than or less than 54 cm? [closed]

I understand how to solve this (when $V_{BC}$ is equal to the emf of the second cell then the current through the second cell is zero). However, I'm curious what happens when the length BC is more ...
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Does the attraction between an electron and proton start a circuit or repulsion between two electrons?

Currently learning circuits and our book states that when a battery is placed in the circuit the electrons toward the end of the circuit wire is attracted to the positive terminal of the battery ...
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Average value of a waveform

I was trying to find the average value of waveform but it came out to be negative. The waveform was: $$v(t)=\cases{2t&if $0<x<1$\\-4&if $1<x<2$}.$$ Can the average value of a ...
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Applying Electron Flow Theory to Alternating Current

I am a beginner to electronics, so please excuse my ignorance. I have been searching endlessly for an explanation, but nothing I have read has fully answered my question. Am I correct to say that in ...
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Would we need Alternating Current if superconducting wires existed?

The major advantage of Alternating Current is that it can be transmitted to large distances without significant losses, which is not possible in Direct Current. Had economical superconducting wires ...
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How is there self-induction at the moment of closing the circuit?

I have just learned about self-induction and I'm confused about something. There was a problem where there was a battery connected in parallel with a bulb both connected in parallel with a coil, the ...
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How many currents are there in a circuit?

I've been studying about circuits lately and I have a difficulty when applying Kirchhoff's rules. My question has to do with how can I find how many currents are in a circuit. I know about junctions ...
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What is meant by “plane of the wire”?

In my textbook, it is given that "The magnetic field produced due to current carrying circular wire at its center is perpendicular to the plane of the wire" What is the meaning of "...
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A Current Electricity Numerical

Q. A cell of unknown emf E and internal resistance r, two unknown resistances R1 and R2 (R2>R1) and a perfect ammeter are given. The current in the circuit is measured in five different situations :...
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Relationship between Electric Fields, Potential Difference and Resistance in Circuits

The battery in a closed circuit creates a uniform electric field in the wire, which pushes the electrons from the negative to the positive terminal. The electrons clearly have more potential to do ...
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What will be the direction of the induced current in the loop due to the other loop?

Say I have a circular loop in which current is flowing which is being increased as time passes by. And beside it in the same plane there is another circular loop which isn't connected to any circuit. ...
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How to determine the voltage difference using KCL and KVL?

Here is what I have done so far: Using KVL (left loop): -12V = (10+10)*i (i = current) i = 0.6A Using KCL (left loop): Ia(current away from resistor) = Ib(current towards 50 ohm) + Ic(current ...
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How do we find the equivalent resistance in a square circuit with 4 resistors along the diagonals in the square? [closed]

In the given circuit diagram, if the red colored parts indicate a resistor with resistance $R_1$ along $AO$, $R_2$ along $BO$, $R_3$ along $CO$ and $R_4$ along $DO$, is there any method using which we ...
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Are AC circuits limited to only a serial connection?

What would happen if you set a condensator, a resistor and a solenoid all parallel to each other in an AC circuit? Would it not work or is there a way?
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How can more voltage give more power (do more work)?

I * V = W 1A of current @ 1V is: 1W 1A of current @ 10V is: 10W I understand that 1A is 1C-per-second, which is some amount of electrons. Intuitive so far. How can I get more power if I use the same ...
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How is Alternating Current (AC) used in Bipolar Junction Transistor (BJT) without ruining its operation?

In a BJT (Bipolar Junction Transistor), say NPN in common base configuration, we forward bias the Base-Emitter Junction and reverse bias the Base-Collector Junction when using a constant DC supply. ...
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Electricity vs Current [closed]

BACKGROUND: Electromagnetism has been the hardest concept in physics that I do not understand at all back in my old school. Now, I just started studying robotics which requires the basic understanding ...
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Is the direction of current wrong in this circuit? Why? [closed]

I know how to measure the equivalent resistance of this circuit, we say R2, R3 and R4 are in parallel combination and I know the reason of this too. But if we consider the direction of electricity of ...
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Will I get shocked if I touch only the live wire while standing bare feet on the dry floor of my appartment?

In contrary to static electricity the mains electricity must return to the power plant. When I touch the live then the current flows through my body and the floor of my appartment and through soil to ...
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In AC, do Electrons move in perfect Sync with Generator Rotation across the whole distance?

While i'm self studying electricity, one interesting topic seemed counterintuitive to me, which is: When an AC generator connects to a long XX KM length cables; each cycle, the electrons in the cables ...
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What material is superconductor at 394 K and 2 Mega Pascals? [closed]

What material is superconductor (high current) at 394 K and 2 Mega Pascals?
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Calculating equivalent resistance by Wheatstone bridge concept

I've been learning about the concept of Wheatstone bridge in current electricity chapter. I attempted to solve this problem by that concept: I don't know if my method is right. I tried to take the ...
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1answer
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If the current of the branches in a parallel circuit always add up to the same total, why isn't this true in this example?

Here is a picture: I did some math and got this table: Why doesn't the current add up to the total, since it's supposed to in a parallel circuit? I used Ohm's law to calculate everything. My ...
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Understanding the zero current in a simple circuit

I've simulated the very simple circuit shown below: As you can see, it has two batteries of 1.5 V, and three identical resistors. The electric currents passing through each wire are also indicated. I'...
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If we connect the two terminals of a semiconductor diode with a simple wire, then will the current flow? [duplicate]

We know that inside a semiconductor diode, there is an internal electric field from the N side to the P side. This implies that the N side is at a higher potential than the P side of a semiconductor ...
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Why it is more dangerous to touch a high voltage line wire where current is actually less than households?

I have seen that power is transmitted from power stations to households at high voltage and low current to minimize the power loss. That means the current in the transmission line is less than the ...

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