Questions tagged [electric-circuits]
An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.
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What does a closed loop mean in Kirchhoff's voltage law? [closed]
Is $\underline{A}CDF\underline{A}$ a closed loop?
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Why is the work through the element the same as the potential difference if we define potential difference this way?(lumped elements)
In the Feynman Lectures on Physics part ||, chapter 22-3 he defines potential differnce like this:
The picture is an element in a curicuit, the black lines on top and the bottom are the conductors, ...
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Why won't all voltage be used up on first resistor in series?
tldr: I am having trouble conceptually understanding voltage between resistors in series, even though I know how to calculate it using Ohm's law. How do the electrons "know" there are more ...
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Air spark temp equation
Is there an equation that can be used to determine the air temperature around a given spark discharge? Let's say I produce a 50K volt spark between two wires using a standard HV generator. I'm sure ...
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Deriving Kirchoffs voltage law using the lumped element model
I have one question about Kirchoffs laws using the lumped element model:
https://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws
The proof is on the Wikipedia page. They say
"Approximate the ...
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Is it possible to charge positively an object using only the higher voltage terminal of a battery?
If electrons move through higher voltage, would a neutral conductive object get charged positively if I were to connect it to only the positive terminal of a battery?
As in, would the electrons would ...
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Why does the voltage goes away in my leyden jar?
This question is similar to this one in the sense that I have my amateurish Leyden jar and I'm supplying ~7.5v from 5 batteries (~1.5v each) in series.
Some details and facts after experimenting:
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Query regarding a published description of a mechanical hydraulic system analogous to $V = IR$ in an electrical system
The screenshot is taken from the wikipedia article for a resistor - https://en.wikipedia.org/wiki/Resistor
I understand that a larger head results in greater hydrostatic pressure, therefore a greater ...
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Current decay in RL circuit
I guess this has been asked before many a times. But I searched for it and couldn't find the question. Any kind of qualitative answer will be really helpful.
When a magnetically charged inductor is ...
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How will a taser act when one neither or only the receiver is grounded?
Person $A$ has a taser and person $B$ is being tased. How will the current affect the two people when :
Neither $A$ nor $B$ is connected to the ground (earthed)
$A$ is earthed, $B$ is not
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If Voltage = Joules/Coulombs than how can you have Voltage without Current?
Note: For the below question: I am ignoring exotic circumstances such as superconductors.
My Problem:
I came across this question regrading the ability to have a voltage without having current.
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What is the emf in this circuit?
There is an infinite solenoid with radius $r$ inside the first loop powered by a current that changes over time so that the magnitude of the magnetic field inside the solenoid is $B(t)$. According to ...
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What does complex permittivity mean?
I have been trying to solve the following question:
$U(t)$ has the frequency $\omega$. Without an electric, the Voltage drop around the resistance is $U_R$. When half of the capacitor is filled with ...
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Can an electron near thar the positive terminal of a battery make it all the way to the positive terminal? [closed]
Following Drude's model of conductivity, can an electron near thar the positive terminal of a battery make it all the way to the positive terminal? The electron is in the wire but near the positive ...
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Which of $I_s$ and $I_p$ will be greater? [closed]
I have two circuits:
A circuit with two cells (emf=$12V$, internal resistance, $r'=0.5 \Omega$) and a bulb (resistance=$r$) connected in series:-
A circuit with two cells (emf=$12V$, internal ...
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Do Electrostatic Charges build up at the ends of an Inductor in closed circuit?
I was watching this video from YaleCourses youtube channel. At around 41.00 minutes, the professor introduces the notion of charge buildup at the ends of an Inductor in a closed circuit.
Is the ...
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How AC circuit "Knows" how to divide the voltage?
Let's say we have an AC circuit with EMF source of $12V$ and a resistor of $3 \Omega$ . Then a voltage of $12V$ falls on the resistor. Now if we add another resistor of $3 \Omega$ , the circuit "...
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Current in each resistor
Switch $S$ is initially in the off or disconnected state. $E$ is the battery electromotive force with an internal resistance, $r$, of $10\, Ω$.
The circuit given is:...
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How to argue that the potential is the same in a conductor with zero resistance when we have electricity?
I am wondering how we can argue that the electrical potential is the same in point A and B in the figure below:
I have seen the argument that in a conductor where the charges are not moving, then the ...
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Why did disconnecting an electrical coil create a jolt in my arm?
Way (way) back in the day, I was doing a physics experiment (LC circuit behavior, IIRC, but that’s not important) part of which involved a large-ish (maybe 12” diameter, 2” thick) desktop coil in a ...
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Why will a circuit and resistors follow Ohms law when we connect different resistors together?
I assume in my question that all resistors follow Ohm's law.
As I understand Ohm's law can be explained such that if we connect a resistor to a power source that is not time dependent then we have the ...
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Why is there an electrostatic field in a closed current?
There is something about the derivation of the formula for parallel resistors I can not understand($1/R_t=1/R_1+\cdots+1/R_N$).
In order to derive this formula we use that the potential is the same ...
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In applications where heating is not the required from of energy, current is to be kept low as per Joules law. What energy is considered useful?
As per this paragraph from Wikipedia
"Joule heating is referred to as ohmic heating or resistive heating because of its relationship to Ohm's Law. It forms the basis for the large number of ...
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Relating potential difference of electrostatics with circuit
Since absolute potential isn't defined for a point, we take a reference point which is $\infty$, and then define potential of a point $A$ to be the work done per unit charge to move that charge from $\...
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Is a simple circuit series or parallel?
Suppose we have a simple circuit in which a battery is connected to only one resistor. Is this considered as series or parallel?
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How much energy was used to charge the inductor? Electrical systems question
I am a math major, and I am taking a mandatory class that looks more like physics and the professor gave us an assignment with a question that I don't have any idea on how to solve it. The question is ...
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Electromotive force in terms of thermodynamics / statistical physics
I would like to understand how electromotive force arises in terms of thermodynamics/ statistical physics. It seems like a rather simple question, but my (admittedly brief) search hasn't produced ...
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Is current (flow of charges) even possible in an ideal wire?
A typical electrical circuit with resistors only can be shown as in the fig.
This is how every book and every website indicates the direction of current in the circuit diagrams.
But I have a doubt ...
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How Does Voltmeter Actually Work?
I've tried to find a specific answer to my question, but couldn't.
My question is why Voltmeter Shows Zero Volts, when we connect the leads not across a resistor (or any other component) but side by ...
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Why a bulb glows with max intensity just after a electric current is set up in the circuit
If there is a electric circuit with a bulb and after i connect a battery to pass the electric current , it will suddenly glow. Lot of people tell that a current is set up instantly due to presence of ...
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Connect negative terminal of a battery to Earth
I have a question about what happens
in following experiment: Assume we have
a battery with two Galvanic half cell,
eg a magnesium and a copper cell.
Since copper has higher electrode potential
that ...
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Why can't only one plate of a capacitor get charged?
In the above image, one capacitor is uncharged while the other is at a potential Vi. If we close the switch then potential difference across both capacitor would become equal(because the upper and ...
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The Concept of Parallel Resistors
If the equivalent resistance of resistors in parallel is lower than all resistors, does this mean each resistor is resisting less than its maximum (what is written on its label)?
I am trying to ...
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What happens if you use a battery to charge up a capacitor fully, and then disconnect the battery, where does the charge 'go'?
The title says it all really, but I think that since the battery is disconnected there is now an 'open circuit'. I know that charge can only flow if the circuit is complete (closed).
But the part that ...
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Sparks via RL circuit
say we have a RL circuit with an direct current source (ie.battery), we have a second solenoid encloses the first coil (like transformars), the second coil is open ended.
Now, we have switch in the ...
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What happens when an electromagnetic wave encounters a resistor?
So I know that the electromagnetic wave travels down the transmission line between the conductors and the fields are related by the characteristic impedance of the transmission line, and I know that ...
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Deriving the equivalent capacitance in a series circuit formula
When we derive the formula for the effective capacitance in series, we say:
$$Q/C_{eqv} = Q/C_1 + Q/C_2 + Q/C_3$$ (if there were 3 capacitors in this case). We would then cancel $Q$ to obtain the ...
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Damped oscillations of galvanometer
The magnet inside a galvanometer is concave, so we get rid of the $\sin\theta$ factor in the magnitude of the torque experienced when there is a current in the coil. So:
\begin{equation}
\tau=NSB
\end{...
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(Too?) simple model of pn junction
I am trying to build a simple model of a pn junction in order to show high school students how it works. I am not looking for something precise, so I use really simple discretization and I discard ...
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Confusion over condition for zero current in potentiometer
Given the below circuit for calculating emf of a battery(sorry about bad drawing), I did some calculations using Kirchoff's 1st and 2nd laws.
In loop 1 (cell E and ABC), we get $E-i_{1}R_{AB}-iR_{BC}=...
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Calculation of internal resistance of battery using potentiometer
In this circuit diagram current $i_{2}$ (passing through the lower circuit) is 0.
Does this mean that the potential difference between c and b is zero? But then why is current flowing through the ...
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Is a Wheatstone bridge with 5 nodes possible?
The statement of the question is to find $R_x$
I think most Wheatstone bridges are of 4 nodes where if a detector is connected in between two nodes, then when the potential difference across the nodes ...
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How do devices control how much power they use?
In power systems (Australian for reference) the grids run at a constant voltage of 220V. I’ve heard of switches were less voltage being used is created by adding more resistors for example to dim ...
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What does 18V signify here?
So in this question in my textbook
I am asked to find the current i. In the solution the relation $i=\frac{EMF_{net}}{R_{net}}$ is used to calculate the current. So here does the 18V signify the EMF ...
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Thevenin equivalent voltage
I am trying to find the Thevenin equivalent of the following circuit:
In regards to the equivalent voltage, I know (I have the answers) that it should be V + IR, but I am not sure how to get there. ...
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Current flowing through it is?
Below is the question. I have seen many answers on it and some of them describes that the (3 ohm, 3 ohm) and (6 ohm,3 ohm) resistor are in parallel. So if they are in parallel it means that the point ...
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Voltage across battery which is being charged
When I connect my 7 V battery (having 7 V voltage ) to a 10 V power supply then across the battery it shows the voltage being the same as the instantaneous voltage of the battery.
Now if I connect the ...
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Why did the defected bulb glow brighter when switched off?
Suddenly an LED bulb in my house stopped glowing (actually it was having very little brightness (can be noticed in the video)). But when I switched off the bulb , it first glows brighter and then ...
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EMF in an LC circuit
What is the emf of the inductor in an LC circuit that is oscillating at a fixed amplitude, without damping, and without an external energy source? Am I right that the emf is zero when the work done by ...
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How can we derive the polarity of the induced voltage in an inductor?
As we know, the voltage-current relation of a two-terminal constant-inductance inductor is:
$v_L(t) = L \, \dfrac{\mathrm di_L(t)}{\mathrm dt} \tag 1$
I've managed to prove that equation without ...
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