Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

0
votes
0answers
15 views

A question on an AC Current calculation. [on hold]

So I got this question and I'm not sure of my steps so here goes: If a 120V rms supply is used to charge a 10A DC device at 14V and the efficiency of the system is 70% then how much current is drawn ...
1
vote
3answers
43 views

What is the voltage in electrical circuits?

I understand what the voltage is and I realize that the battery makes an electric field due to the accumulation of the charges in the anode and cathode this electric field causes electric potential ...
-1
votes
2answers
29 views

Is voltage basically the measure of the strength (or density) of an electromagnetic field? And does an increase in voltage increase the amperage?

I have been in the process of fully understanding what is generally accepted as truth by the scientific community regarding voltage, watts, and amperage. Most engineers seem to say to simply use the ...
0
votes
0answers
12 views

Is there a limit on the magnetic field in a Hall generator?

In a Hall generator, charge accumulation on electrodes occurs because there is a generated current, $\bf{J}$, in a magnetic field, $\bf{B}$. This results in charge separation due to a Hall current ...
1
vote
2answers
57 views

Magnetic field in Ohm's law

In a linear, stationary, isotropic, homogeneous, only time-dispersive medium one usually writes Ohm's law as: $$\underline{\mathcal{J}}(\underline{r},\omega)=\sigma(\omega) \underline{\mathcal{E}}(\...
2
votes
1answer
20 views

Conceptual question on volume current density and derivation of the continuity equation

The expression for the volume integral of the volume charge density is $\int_{V} (\nabla \cdot\vec{J}) d\tau = -\frac{d}{dt} \int_{V} \rho d\tau = -\int_{V} (\frac{\partial \rho}{\partial t}) d\tau$...
-1
votes
0answers
21 views

Semantics problem with physics definition [closed]

Definition of current: Rate of flow of electron then, " The electric current is flowing" would be a wrong phrase due to the above definition if we replace the current in the above phrase with Rate ...
0
votes
0answers
48 views

Does a relationship exist between current, acceleration and charge? [on hold]

I was looking through a study guide question and came across a confusing problem. Here's the setup: A cross consisting of two wires is first placed in a cartesian coordinate system with the ...
-2
votes
0answers
23 views

How to solve this from RC circuit? [closed]

Find the potential difference across 3 ohm resistor and 3 microfarad capacitor in steady state
-1
votes
0answers
19 views

Calculating the current & p.d. using only the terminal p.d. and resistance in series and parallel [closed]

I've done the following calculations but I am not sure whether these are correct. So in circuit 1 (C1) , using V=Ir the current in the circuit is V/r = 1.5/2 = 0.75. Thus the current through the lamp ...
1
vote
1answer
18 views

What is the EMF in a bar rotating around any point?

The problem of a bar (or rod) of length $l$ rotating around one of its ends in a magnetic field of magnitude $B$ is very well known. The induced emf is $\frac{1}{2}B\omega l^2$, where $\omega$ is the ...
0
votes
4answers
38 views

Can Induced current be obtained by only changing the direction of the Magnetic Field?

According to Faraday, a change in magnetic flux induces current in a conductor. Just suppose we take a circular coil, and pass a magnetic field inside it, and keeping changing the direction of ...
-1
votes
1answer
34 views

How a battery maintains the current in the circuit? [duplicate]

How a battery maintains the current in the citcuit? Iwant to know each and every step of this process mathematically and theoretically also.
1
vote
5answers
1k views

Why does a 60W bulb glow brighter than a 100W bulb in a series?

In my physics class I have this problem that shows two lightbulbs, one 60W and one 100W in series, connected to a 120V battery. The problems are: Which bulb is brighter? (A: 60W) Calculate the ...
12
votes
8answers
3k views

Electrical Current vs Power in layman's terms?

I am trying to understand electric circuits (ie voltage, current, power, and resistance). For the most part, everything makes perfect sense, but for some reason I do not feel as if I understand the ...
0
votes
1answer
33 views

Movement of electrons in a circuit

Electrons move from negative to a positive terminal, but their path seems unusual. They seem to be taking the longer path to get to the positive terminal, The electrons could have gotten closer to ...
0
votes
1answer
20 views

Magnetic Force on a current carrying conductor

Why does a current carrying conductor parallel to the magnetic field not experience a force?
0
votes
0answers
16 views

How to calculate the current generated by a thin film?

I have a thin film with known dimensions and conductivity. If I hook up wires and apply a bias, how can I calculate/estimate the current that I will get? Here is where I'm at: $$ \mathbf{J}=\sigma \...
0
votes
0answers
14 views

Levitating Super Conductor - Quantum Entanglement or Electric Currents? [duplicate]

In this video (https://www.youtube.com/watch?v=zPqEEZa2Gis) the explanation given for levitation of super conductor is simple electric currents creating opposing magnetic field. In a similar ...
11
votes
5answers
1k views

What's the reason behind the current remaining the same after passing by a resistance?

I've been wondering why does this really happen, I mean by intuition if electrons are driven by EMF (ignoring wire's resistance), $n$ coulombs would pass by a point per second, until they encounter ...
1
vote
0answers
38 views

Why doesn't current flow between the wires in a coil?

Didn't find the answer online, maybe because of bad searching. So hope you here can give me an explanation. In an engine or transformer the coil is tightly wired, but how come the current doesn't ...
1
vote
1answer
32 views

Surface current density confusion

From Griffiths' Intro to electrodynamics: Now I'm confused about 3 things: 1) What is the 'mobile' surface charge density? Isn't the surface current density itself the 'mobile' surface charge ...
0
votes
0answers
42 views

Uniqueness of the current loop inverse problem

Imagine we have a circular planar current loop where the current contour is infinitely thin. Free parameters of this loop will be: coordinates of the center; current density $I$ and sign; radius of ...
0
votes
0answers
20 views

How to create a hysteresis diagram using the mass of iron filings and current of an electromagnet

My lab report is based on determining the strength of an electromagnetic when changing the current. My method includes raising the current from 0 to 2 and back down from 2 to -2 and calculating how ...
0
votes
1answer
21 views

How to explain these observations on the first load, with two loads in series?

Recently I purchased the Snap Circuits Jr. kit and was working through the different projects with my daughter. We decided to connect two loads in series circuit, powered by the battery source. The ...
0
votes
1answer
50 views

Ampere's Circuital law proof for closed circular loop

How do we prove the magnetic field for a circular loop is $\frac{\mu_0I}{2r}$ using Ampere's Circuital law I proved it using Biot-Savart Law but i am getting $\mu_0I/2\pi r$ instead of $\frac{\mu_0I}{...
1
vote
0answers
38 views

How is current in superconductors increased microscopically?

Imagine a superconductive ring with its current being increased by EM induction. How is current increased microscopically? I see only two possibilities: ...
0
votes
0answers
20 views

What is the electrical resistivity of air during breakdown?

There is a well-documented theory for breakdown voltage vs pressure in the form of Paschen's law. But what is the trend of the electrical resistivity of air as a function of the electric field ...
1
vote
0answers
21 views

Proof that true passive linear memristors doesn't exist

This is a sequel to the following (now irrelevent) question: My attempt to implement linear memristor Assume the "conceptual symmetry" of the fundamental passive circuit elements holds: Then let's ...
1
vote
0answers
33 views

COMSOL magnetic field time dependent [closed]

enter image description here I need to modelling conductor in Comsol 5.3 by MF physics in Time Dependent study Conductor model "Single conductor" in "Coil" feature doesn't work in TD study, and ...
-1
votes
3answers
79 views

Does touching the Live wire makes it neutral?

If I have two 'hot' wires connected to a source and a load, and one of the wire is connected to the ground, this wire is called the 'Neutral'. But what happens if instead of using an additional wire ...
2
votes
2answers
26 views

Why doesn't ionized air give you a current shock?

According to Tesla coil, the air gets ionized and why doesn't ionized air give current shock to a person standing in the ionized air?
0
votes
0answers
10 views

What is the advantage of a double pole switch over a single pole switch? [migrated]

I know that a double pole switch is used to cut off the current in both live and neutral wire simultaneously, but by using a single pole switch,if you switch off the current through the live wire, the ...
0
votes
1answer
27 views

Conservation of bound charge? [closed]

It is intuitively obvious that free charge is conserved in vaccum. But when is bound charge conserved? I tried to find this by formula: The charge conservation law in microscopic view (Assuming there ...
2
votes
2answers
91 views

In superconductivity, does the diameter of the cable affect the current?

In the water tank analogy below, the smaller diameter pipe (B2) will drain tank A slower than the larger diameter pipe (B1) We are told that resistance has this same effect on current the bigger the ...
1
vote
1answer
29 views

How do I experimentally measure the resistance from using dielectric grease on battery posts?

The internet gives lots of contradicting advise about greasing or not greasing car battery posts to prevent corrosion. So rather than rely on the internet, I want to perform an experiment so that I ...
2
votes
2answers
57 views

Touching single line of AC Power and charge oscillation in body

If a person touches a single line of AC(Only on the live line, and no where else. Say he/she is hanging on the power line using one hand) as shown in the attached image, Do the ions in his/her body ...
0
votes
2answers
54 views

Why is the electric potential difference independent of resistance?

According to wikipedia the definition of electric potential difference is as follows: The difference in electric potential between two points (i.e., voltage) is defined as the work needed per unit ...
0
votes
1answer
60 views

Charge accumulation in wire

I came across a question about charge accumulation. It states that if a steady current flows in a wire composed of a copper and iron wire of same area (see fig), will the charge accumulate on the ...
-2
votes
3answers
45 views

Do magnetic lines of force depict path of moving charges [closed]

What are the magnetic field lines basically depicting in terms of moving charges or charge carrier particles or currents. What do those circular loops around a straight current carrying wire actually ...
-1
votes
1answer
34 views

is this the reason why current doesn't flow over a resistance if there is another path without resistance? [duplicate]

Let's suppose that a single battery is connected with a wire, which does not have resistance. Electrons will start to flow , in reality, with a wire with resistance, a potential difference would be ...
0
votes
1answer
48 views

Does a battery 'excites' current to flow in a superconductor? [duplicate]

If yes, how is it possible since a closed circuit with no resistance means 0 voltage, how does the electrons flow initially if there's no potential difference? Any simple explanation or analogy would ...
-1
votes
2answers
116 views

Is my understanding of current correct?Urgent help is needed! [closed]

I had asked this question:No matter the arrangement of resistors in a circuit, a battery will still produce a current as if it were connected to an imaginary combination of the individual resistors ...
0
votes
3answers
35 views

How does the initial turn-on transient decay into the steady state in a given circuit?

How does the initial turn-on transient decay into the steady state in a given circuit? For example, in a parallel circuit, how does the voltage over both arms of the parallel circuit equal to that of ...
1
vote
2answers
135 views

Hardest circuit diagram

I have provided an example of the type of problem I am having issues with. In the given diagram, the resistances and batteries are identical and the batteries do not have internal resistances(for the ...
0
votes
2answers
61 views

How does the current become homogeneous within a circuit?

I have two questions: In a given circuit with resistances of different values connected in parallel, there is a different build up of electrons when the power source is turned on. Then, how is the ...
0
votes
1answer
54 views

Realistic energy output of a battery

An answer from the post "Battery life with hot and cold wires" talks about Peukert's law related to the battery capacity. Now, within the scope of undergrad electromagnetism courses, the following are ...
0
votes
2answers
37 views

Compare the time the power sources in these circuits will last

I am trying to conceptualize the time which a battery will last in a given circuit. Below is an example from which I will explain the questions which I am struggling with : Lets begin by asking this ...
65
votes
13answers
13k views

Why doesn't current pass through a resistance if there is another path without resistance?

Why doesn't current pass through a resistance if there is another path without resistance? How does it know there is resistance on that path ?
-3
votes
1answer
45 views

Circuit Diagram Problem [closed]

I solved a problem in which I was supposed to find the current over the ammeter. The answer is 12 because the total voltage over the circuit is given as 128 V. However, I do not understand why we don'...