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Questions tagged [electric-circuits]

An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.

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How is Maxwell's second equation true here?

$\vec{B}=\nabla \times \vec{A}\tag1$ This is true because at every point $\nabla\cdot\vec{B}=0 \tag2$ In free space points, $\displaystyle \vec{B}=\dfrac{\mu_0}{4 \pi}\int_C \dfrac{I\ dl \times\hat{...
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0answers
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Why is the maximum voltage applied to the coil different when disconnected from the battery?

In this RL circuit, the time to reach the point V=0 (after the switch was turned to (a)) was about the same as the time after switched to (b). But my teacher says, (in the experiment) peak voltage ...
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1answer
45 views

Finding the Internal Voltage and Resistance of a Battery given the behavior of the circuit it's part of

I am tasked with finding the internal resistance and voltage of a battery. I am given the following: A simple circuit consists of a real battery and a resistor in series. When the resistor's ...
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1answer
37 views

How do multi-meters measure capacitance?

Many multimeters have the ability to measure capacitance along with the ability to measure AC voltage, DC voltage, current, resistance ... The only equations I am aware of that determine capacitance ...
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1answer
29 views

How to measure Electromotive induced force and current?

I'm doing an experiment on Faraday's law. I have a 100times looped wire connected with a galvanometer. and I will use a magnet to induce current by putting it in and out of the loop. and, I'd like ...
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1answer
70 views

Current as a function of time RL-circuit [closed]

The switch, S, in the circuit has been open for a long time. At t=0 it suddenly closes. Calculate the current through the inductor, $I_L$, as a function of time. Resistance in the inductor can be ...
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2answers
281 views

Are Kirchhoff's Laws violated in case of varying magnetic field?

I was watching a video of Walter Lewin (8.02x-Lecture 16 to be precise), where he demonstrates an experiment which violates the Kirchhoff's Law. The way I interpret Kirchhoff's laws is by ...
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1answer
36 views

AC current and the light of our house

We get an AC current in our house whose value changes constantly Once it becomes positive once it becomes negative and sometimes zero. So why a light glowing in our house does not blink if there is ...
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1answer
89 views

Why is there no potential difference between my body and neither terminal of a battery?

Right now I'm holding a voltmeter. I measure the voltage between terminals of a AAA battery. It reads 1.47V. Next I measure the voltage between the positive terminal of the battery and my hand (I'm ...
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2answers
60 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 ...
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1answer
29 views

Why can a network be replaced by an equivalent network according to this definition of equivalence?

My textbook's definition for equivalence of two electrical networks: "Two networks are said to be equivalent at a pair of terminals if the voltage current relationships for the two networks are ...
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2answers
57 views

Can a thin wire drive high currents if it's properly heat sinked?

Assuming electrical resistance is only a result of heat inside a wire. If we take a thin copper wire acting as a fuse between two higher gauge wires, and we wrap it with a non-conductive material to ...
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1answer
43 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 ...
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1answer
61 views

Inductance in Superconductors

This is a picture I got from a question in this website, it seems totally fine, but if you try looking it gain, is the heater placed in the wrong position? Because as I know current takes the path of ...
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1answer
49 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 ...
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2answers
127 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 ...
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3answers
44 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 ...
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2answers
50 views

Why doesn't current exit an appliance through the earth wire?

Any appliance with a metal body has three pins, the thickest and longest one leading to the earth conductor because of it's low resistance. In that case, why doesn't the current exit through the earth ...
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3answers
92 views

What determines the voltage in a battery?

This diagram problem has got me thinking about what determines the voltage in a battery. At school, we were taught this method of giving a value of voltage to points in a circuit. However, I do not ...
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2answers
95 views

0 Resistance in Parallel Circuits [duplicate]

If two resistors (5 Ohms & 10 Ohms) are connected in parallel, current will flow through both resistors. Then, assume a parallel circuit (5 Ohms & 0 Ohms), why does current flows to the path ...
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3answers
308 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 ...
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2answers
73 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 ...
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1answer
60 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 ...
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1answer
21 views

Effect of an external electric field on a electric current

I'm wondering how an external electric field influences an electric current in a conducting wire and how could we measure this effect. Without an external electric field, the conducting medium ...
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2answers
39 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 ...
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13answers
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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 ?
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1answer
53 views

Potential divider formula

Hi, does applying resistance to a potential divider affect the output voltage? For example, if I were to put resistor R midway across a variable resistor would output voltage still = (R1/R1 + R2) x E? ...
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1answer
35 views

Why do we need to have a low voltage drop over long distances in transmission of electricity? [closed]

It is said that AC is preferred over DC because of the negligible voltage drop over long distances. How does that work?
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1answer
39 views

Overdamped RLC circuit

I have a series RLC circuit with an equation: $$\frac{d^2I}{dt} + 2\alpha \frac{dI}{dt} + \omega_0^2 I = 0$$ (No outside sources affecting the circuit, only some $I_0$ was in the circuit at the ...
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2answers
49 views

Work done by electric field in a wire

Work done by electric field in moving a unit charge is the potential drop. In wires voltage (potential drop) is given by ohms law. Can somebody explain to me why work done by electric field can not be ...
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1answer
47 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'...
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1answer
119 views

What is the difference between EMF of a battery, its potential difference and the current supplied by the battery?

Now, I know that emf is measured using an ammeter, while potential difference is measured using a voltmeter. But why is that so? What do we mean when we say the emf of the battery is say, 3V, and the ...
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5answers
110 views

What exactly is “voltage drop” across a circuit element?

what exactly is "voltage drop" across a circuit element? I don't quite understand what this means.
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1answer
36 views

Solution of Linear Electrical Circuit

We learned in class that the number of independent KCL equations is N-1(N-number of nodes) and the number of independent KVL equations is B-(N-1) (B- number of branches). Thus we have B independent ...
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2answers
23 views

As there is a potential drop across resistance, then why in parallel circuits the voltage across resistances is same as that of battery?

In textbooks it’s taught that in parallel circuits the voltage across resistances is same as that of battery but after that we also read the concept of potential drop across resistances, which creates ...
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1answer
120 views

Why is the power of a filament lamp directly proportional to the cube of its voltage?

I was doing a textbook question on how the power of a bulb varies with the potential difference across it. I plotted this graph: (V is on the x axis and P is on the y axis.) I was then told that ...
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0answers
209 views

Infinite triangular Resistance [closed]

A classic problem but I couldn't find the answer I want. Determine the resistance between the points A and B of the frame made of thin homogeneous wire (as shown in figure), assuming that the number ...
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3answers
56 views

Where does all the voltage go?

My understanding of this circuit is that the capacitor must 'use up' all the voltage across the terminals of the battery. If you double the distance between the plates, I would assume the voltage ...
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1answer
36 views

Electrical circuits and calculating resistance [closed]

Can anyone give me some ideas about how to simplify this circuit....
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3answers
136 views

How to determine direction of the current in the following circuit? [closed]

What would be the direction of the current on R3? Can there be current moving in both directions?(left and right?)
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2answers
166 views

Magnetizing inductance in transformer

I asked this question in electronics stack exchange as well but I thought it would also be applicable here as my question revolves largely around Maxwell's equations. I am learning about transformers ...
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2answers
113 views

Charge distribution in the wires and resistor, in a DC circuit

1) How do the electrons in a wire with 0 or negligible resistance arrange themselves in order to make the field in the wire 0? 2) The electric potential drop across a resistor is far more than ...
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3answers
64 views

Why does the full PD across a battery manifest itself across a break in a circuit at any point?

Consider the following circuit: I want to know why the full pd of the battery can be measured across the break if a voltmeter was connected. Surely when the whole circuit was closed the charges at ...
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4answers
76 views

How do charges lose electrical potential energy when going through a resistor?

I can understand that the charges need to do work against the resistance - which transfers energy to forms such as light, heat, etcetera - using the electrostatic force provided by the battery ...
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2answers
67 views
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1answer
57 views

Electric Potential drop in wires

Electric potential is related to Electric Field by negative integral of Field with distance.If charges move away from the positive terminal (Assuming conventional flow) why is there no drop in ...
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1answer
138 views

If live & neutral alternates, why is neutral always $0V$? [duplicate]

So I've been confused on why the neutral is always at $0V$, I know that because it is earthed, but the concept that I know about AC Current that the Voltage keeps alternating ex(from $+240$ to $-240$)....
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2answers
73 views

Charging a battery

So we have a charger outputting V volts and $I$ Amperes and two rechargable batteries of the same capacity $Q$ coulombs but different emf's $V_1\&V_2$. Which battery would charge faster? ...
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1answer
108 views

Poynting's vector and its application to circuits

If I had a circuit as shown in the figure with the battery and the capacitor being covered completely, save for a passage for the conducting wire, by a hypothetical material that doesn't allow ...
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1answer
30 views

DC Battery Charging Question

I have a 7.4v LiIon that hold 1450ma. I have a variable DC bench power supply that I can crank up or down and adjust as needed. I want to quickly charge the battery and noticed if I adjust the ...