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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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3answers
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Why is a net flow of positive charge in one direction equivalent to a net flow of negative charge in the opposite direction?

If I understand correctly, conventional current was defined with reference to positive charges because it was found that a negative charge flowing in one direction is actually equivalent to the same ...
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0answers
28 views

Exponential fit in Origin doesn't converge

I am using a data treatment program called Origin, wich I think many of you are familiar with. The data I have is time vs voltage in the resistor of an RL circuit. The expression that describes the ...
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0answers
24 views

$j$-$\omega$ method alternating current circuit help [closed]

I'm suppose to calculate the current and the phase angle. Can someone please tell me if this is the correct solution?
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2answers
37 views

Kinetic energy and current

When a battery is connected to a resistance circuit, we know that it loses energy because heat is emitted as a result of the collisions between the electrons and stuff, but my question is, is the ...
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4answers
39 views

Finding the charge on a capacitor (RC circuit)

I am having trouble finding the charge on the capacitor for $t\rightarrow \infty$ after the switch has been closed at $t=0$. I already know the current $I$. I also have to find out on which sides the ...
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1answer
36 views

Electric current in a circuit with two batteries [closed]

I have the following circuit                             &...
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1answer
60 views

How to find equivalent resistance and equipotential points in these types of circuits [closed]

(https://i.stack.imgur.com/r6thV.jpg) we're supposed to find equivalent ressistance between A and B Where to START the circuit simplification in these types of question where all the resistors are ...
2
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1answer
68 views

Resistors parallel to short circuit

I have a trouble solving this problem. (Actually, each resistor is not parallel with the bottom wire since the voltage across each of them is different with that of wire.) In the manual, the bottom ...
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1answer
28 views

Why isn't $V_L$ not equal to $i_LR_L$ according to Thevenin's theorem?

According to Thevenin's Theorem $I_L= \frac{V_{th}-V_L}{R_g}$ whereas $I_L$= current through the load. $V_{th}$= The potential difference across the load resistance when the load resistance is ...
44
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13answers
9k views

What *exactly* is electrical current, voltage, and resistance?

I am taking AP Physics right now (I'm a high school student) and we are learning about circuits, current, resistance, voltage, Ohm's Law, etc. I am looking for exact definitions of what current, ...
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0answers
27 views

Transformer Equation Confusion

I have read some posts on here which I think to revolve around my problem too but couldn't really understand the explanations. So basically, I have seen how the Transformer equation is derived: $\...
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1answer
58 views

How do resistors form electric fields and thus potential drops?

$$V_{ab}=-\int_b^a\vec{E}*\vec{dl}=\int_a^b\vec{E}*\vec{dl}$$ By Kirchhoff's loop rule, the sum of the potential drops across a closed loop is zero. Going in the direction of conventional current ...
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1answer
43 views

Please tell me how to solve star resistance network [closed]

Please tell me how to solve star resistance network I have tried solving it, but the connection between the crossed resistances is confusing me.
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2answers
45 views

What happens when very high resistance is connected parallelly with low resistance

$1.$What happens when a resistor of very high resistance (say $10,000 \Omega $) is connected in parallel with a resistor of comparatively lower resistance of about (say $100 \Omega $)? Is the ...
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0answers
30 views

Why does applying a voltage through the gate on a transistor help lower the potential barrier?

At the potential barrier, all that atoms are "satisfied"; they each have the appropriate number of electrons in their valence shell since the free electrons on the n-type side fill the holes on the p-...
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1answer
16 views

How can I model a homogenous circuit element that localizes current?

This question is inspired by the single-wire earth return power transmission systems used in very rural areas (Wiki). Consider a power distribution system with a generator in the middle, connected ...
1
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1answer
104 views

Will electricity follow a path of least resistance on a rotating conductor?

I would like to know if electricity will follow a path of least resistance on a rotating conductor. Please reference the drawing below. This is showing a rotating non-conductive disc with a strip of ...
1
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1answer
53 views

Why does the Voltage of a Capacitor change in an alternating current (AC)?

I have a question about charging a capacitator in an alternating current. If the process starts the current charges the capacitator, therefore the voltage on the capacitator will be increased. Now the ...
0
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2answers
36 views

What will happen if an ideal current source is connected to a isolated resistance?

I know that ideal current source is a theoretical thing. But when it comes to solve problems we have to consider these scenarios. Now suppose an ideal current source is connected with an isolated ...
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1answer
104 views

Would Kirchhoff’s rules not hold in this circuit?

On my E&M test I was given the circuit diagram below and asked to find the charge on the capacitor after a long time or as $ t \to \infty $. In class we had used Kirchhoff’s voltage rule on the ...
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3answers
101 views

Why does the potential along a uniform current-carrying wire vary with the distance along it?

Is it because as the electrons move further through the wire they lose more energy due to resistance? Also, in this context, I believe potential refers to the electric potential energy but I am unsure,...
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1answer
44 views

How do electrons gain energy in a cell?

When electrons reach the positive terminal, how does the cell do work on them? I’ve read in a book that states voltage is literally the push that the cell exerts on electrons, which thus does work on ...
1
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1answer
57 views

Classical Explanation for Electron-Ion collisions

Classically, electrons collide with other electrons and massive (by comparison), stationary positive ions as they conduct down a wire when an electric field is applied. Is there a good mechanism ...
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2answers
36 views

Current law explained

Kirchhoff's Current Law (KCL) is experimentally proven but what exactly happens?. I have made a model by taking the drude model and adding the interactions between the electrons and the reason why ...
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1answer
102 views

Battery operation, charge and discharge processes misconceptions

I'm trying to elaborate a simple and concise explanation (and conceptually correct) of how a battery charges and discharges, and why we say things like "the charge stored in the battery is x Ah". For ...
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1answer
53 views

What can cause the experimental power output to be lower than the theoretical one?

For a lab experiment, I was tasked with finding the power output of the circuit below I am pretty confident that I measured all of the variables correctly (DMM). I have also gone over my notes ...
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2answers
34 views

Is the voltage between the two points $A$ and $B$ denoted as $U_{AB}$ or $U_{BA}$? And why?

Consider the following circuit Is the voltage between the two points $A$ and $B$ denoted as $U_{AB}$ or $U_{BA}$? And why?
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1answer
41 views

Does energy conversion happen when an electromagnet attracts an object?

I am doing science with my 6th grade son, and there is a circuit with an electromagnet (as below) When asked to describe the energy conversion when the switch is turned on, part of the answer ...
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0answers
159 views

Imaginary Capacitance and Imaginary Inductance interpretation [closed]

Today I came across with Complex Capacitances and Inductances for the first time: $$L(j\omega)=L_{real}+jL_{imaginary}$$ $$C(j\omega)=C_{real}+jC_{imaginary}$$ So I started looking at their meaning. ...
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1answer
37 views

What is the equivalent of kinematics for electrics or hydraulics

Mechanical-electrical and electrical-hydraulic analogies (system equivalences) are well-known. Kinematics is when you describe the motion of a body without considering forces. Disregarding the ...
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0answers
25 views

Electromagnetic Dipole, elementary question

Question Of Understanding to the Dipole: does the coil have an induction current running contrary to the current coming from the Capacitor, which role plays this current in the dipole? Otherwise, a ...
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0answers
19 views

LCR circuit , impedance, imaginary [duplicate]

What is the physical interpretation in behind impedance of capacitor and inductor? we know that resistance oppose the current in the same direction of voltage. But how capacitor and impedance oppose ...
0
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0answers
30 views

How to choose the method of circuit analysis?

I was just doing some revision, and I was wondering how to figure out which method to use for solving a given circuit? I tried using mesh analysis on the attached circuit but I got it completely wrong....
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7answers
1k views

Inductor and Capacitor in Parallel

I've been staring at this for 10 minutes and I'm soooo confused. Hopefully, you guys can help! So, let's say we close the switch. From what I understand, the capacitor will charge up to $10V$ almost ...
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0answers
22 views

Formula for total current and phase angle in function of given currents and phase angles in the branches of a parallel RLC circuit

Consider this parallel RLC circuit powered by an sinusoidal alternating voltage and two branches, one containing an ohmic resistance $R_1$ and a capacity $C$, the other one containing an ohmic ...
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0answers
41 views

Derive the formula for a capacitive voltage divider?

I've seen the derivation for a resistive voltage divider, Vout = Vin * R2/ (R1 + R2). For a capacitive divider, Vout is reported as Vout = Vin * C1/ (C1 + C2) - for example see https://en.wikipedia....
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1answer
34 views

Need help understanding KVL in Phasor Notation

I may be missing some crucial observation but I'm getting stumped on this KVL proof for phasor notation. So to prove KVL in phasor notation I'd like to start off with what we know, KVL in a real ...
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0answers
20 views

Finding the inductance of a laser given things like wire length, peak power, and peak current

I am operating an RCA GaAs diode laser operating near $904$ nm designed to be in pulse mode. The driver circuit for the pulsed diode laser is below: With the repetition rate of the trigger set at ...
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1answer
84 views

Two Capacitors One Resistor [closed]

The initial charge of the capacitor C1 is $q_0$ and capacitance is $C_1$ and capacitor C2 is $0$ and capacitance is $C_2$. When the switch S is closed the first capacitor charges the second one and ...
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1answer
27 views

What happens to the energy of capacitor or a coil?

Imagine we add power to a circuit, stationary power, the resistance will transform the energy to heat, but what will happen to the coil's energy, or to the capacitors energy? They will go back to the ...
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1answer
43 views

Understanding Kirchhoff's Loop Law

I'm trying to understand how voltage works in circuits, and currently I'm stuck at Kirchhoff's Loop Law. Suppose we have a simple circuit, just a battery and a resistor. Our battery supplies a ...
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1answer
158 views

Infinite ladder of capacitors [closed]

Why isn't the equivalent capacitance C only? The charge through each capacitor can be 1/2 of the previous capacitor and the sum of the voltage drops will be equal to total voltage. This gives the ...
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0answers
79 views

How does electricity travel near the speed of light if electrons drift at a snail pace? [duplicate]

I was in a reddit argument with someone who said electrons didn't flow at the speed of light in a circuit. Then he linked the Wikipedia page for drift velocity and defeated me in one fell swoop. Now, ...
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2answers
46 views

Understanding the potential difference of a wire

I'm trying to understand the fundamentals of potential difference in circuits. My understandings (from textbook and stackExchange): Potential difference is created by a separation of charges. A ...
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0answers
30 views

How would this circuit behave? [closed]

A function generator is hooked up to two resistors in series. The voltage across the function generator changes over time, shown by the different graphs The questions ask to find the output voltage ...
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1answer
15 views

Electrical systems with multiple connections to earth - is earth modelled as one region of equal potential here?

In the picture we can see a realization of a TT-System, an electrical system with multiple connections to earth at different localiations. I allready know (from this question) that the coulomb-...
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1answer
28 views

Initial Current of Inductor?

I know that a capacitor can be charged up to store energy, then if we disconnect the capacitor from the source and hook it up to a light bulb, it will light up since the energy stored is used to power ...
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1answer
55 views

Resistance and temperature relationship

When the temperature changes from $\theta_1$ to $\theta_2$, having $\alpha$, and the amount of resistance ($R_1$) in the previous temperature ($\theta_1$), we can calculate $R_2$, the amount of ...
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1answer
65 views

Calculating electrical resistivity of a material

If I plan to measure the resistivity of a high resistivity material, would it not make sense to alter the geometry of the sensor to make A/l as small as possible and reduce the voltage to get a low ...
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0answers
24 views

Question about amp-hour and batteries in series

I am a little confused about this wiring batteries in series and parallel and the effect of this on total time that these batteries can last(I suppose this is called amp-hour, correct me if I'm wrong) ...