Questions tagged [electric-circuits]

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

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If no current is able to flow through a capacitor what will be the node voltage on the other end of the capacitor opposite the voltage source?

I'm working on a simple circuit problem including a capacitor and I am calculating the node voltage Va. By using KVL, I find that Va is 5V. But how does the 5 volts appear on at Va if it is not ...
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Would you believe the electron pushing theory in a conductor?

Some people told me that, its the electrons doing all this current generating stuff. do the valence electrons really shift from one atom of the conductor to the other atom of it producing the drift of ...
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Parallel serial battery connection

Here is a classic serial-parallel battery connection schematic (to be more clear, I'm talking about lead-acid batteries): Batteries 1->2 (A-B-C) and batteries 3->4 (D-E-F) are connected in ...
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Voltage and potential energy in a circuit

I'm wondering about the meaning of voltage in a circuit. Voltage is always described as related to the potential energy of the charge carriers. Often, the analogy is made to gravitational potential ...
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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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Resonant Circuits [closed]

So I have this circuit which is resonating, and I want to know how to calculate the output voltage, does anyone have any ideas on how to do this?
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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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Max frequency of Helmholtz coils

What is the max frequency achievable with helmholtz coils? And is the magnetic field as strong as a dc electromagnet or does it lose strength with the increase in frequency?
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How does the MLX90614 work with two different positive and negative thermopile?

In an electrical circuit, positive with positive or negative with negative is not possible, but how about this circuit diagram : there's ground (ground usually negative as far as I know) on the left ...
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What is the meaning of inferred absolute zero temperature? Why does the resistance temperature graph it is obtained from behave that way?

I asked this on the Electronics Stack Exchange and someone suggested for me to ask it here too. https://electronics.stackexchange.com/q/542983 Studying basic direct current circuits, I've come across ...
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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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I have derived that the impedance of a capacitor varies with time

For a closed electrical circuit comprising only an alternating current generator and a capacitor, I have derived that the ratio voltage/current of a capacitor is not constant. As Wikipedia defines it, ...
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Overdamped dynamics and minimization principles

Most physicists are familiar with Hamilton's principle, which allows us to derive the equations of classical mechanics from the principle of stationary action, $$\delta S=0.\tag{1}$$ At the same time, ...
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Grounded/Earthed electric circuits

I have a problem here that involves a circuit that is grounded at the point shown at the bottom the circuit. The units marked with C are all capacitors and Uv is a voltmeter. I haven't seen any ...
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What equation should I use to calculate inductance of a wire coil?

I've been working on a project recently which requires me to build an inductor, however in my research I found many different equations (with a range of variables used and giving very different ...
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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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Mutual inductance - induced magnetic flux in the primary

Let there be two coils, L1 (with self inductance L1), and L2, with self inductance L2. The first coil is connected to a sinusoidal supply, and the second one is connected to a resistor load, as shown ...
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Does the “electricity saving box” work? [migrated]

https://electrical-engineering-portal.com/the-real-truth-behind-household-power-savers concludes Power factor correction devices improve power quality but do not generally improve energy efficiency (...
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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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Interpretation of potential difference of a capacitor

Suppose I have 2 charges of arbitrary charge separated by a distance of 2a. The potential at a point, say A, finite distance from the two charges is the sum of the potentials at that point because of ...
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How is the rotational energy of a black hole converted into a magnetic field used to power relativistic jets?

When an electric charge is lowered into a nonrotating black hole it will "spread" itself across the surface, and the surface will behave like an electrical conductor. Why does this spread ...
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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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Does the sum of power supply in circuit equal zero? [closed]

Just like in the question, I want to know if the sum of power supply in the circuit is really equal zero and if it is true what is the reason behind it. For what I think, power supply shouldn't be ...
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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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What is the difference between static electricity and electricity from a battery/power plant?

Static electricity An object holding a static charge has an electric potential. If it touches an object with different electric potential a current will pass until the potentials are equalized. One ...
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How can a coil self-induce voltage at $t=0$?

Assume you have a resistor and an inductance in series. When a DC supply is connected at t=0, the coil is inducing an opposing voltage, which is the same as the DC supply's voltage. The current ...
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What happens when a battery discharges?

Questions I am interested in: What determines the amount of current a battery can supply? What changes when a battery discharges - voltage, max current, or both? What is the best predictor of the ...
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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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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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How to find the transfer function for steady state? [closed]

I can not find the transfer function for sinusoidal input could you please help me find out the solution or at least where to start! i have found the transfer function Vo(s)/Vi(s)=1/(2j+1) but still ...
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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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Interchangeable arms in Wheatstone Bridge

I came across this fact recently but cannot seem to make much clarity out of it. With reference to the picture above the condition for balancing the Wheatstone bridge is that B and D should be at the ...
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Does a power station directly control the supplied power or voltage?

The electric grid's "job" is to provide to the end user a steady sinusoidal A/C voltage with an RMS value of 120 V and a frequency of 60 Hz. (That's in the United States - other countries ...
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Fermi-Dirac statistics and electrical filter

The graph of Fermi-Dirac distribution near absolute zero and an electrical filter looks very similar. My question is does: this similarity finds any application? I can't think of any scenario as such: ...
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Wet fingers / dry fingers completing a small DC circuit

I am playing with a toy DC circuit. It has 2 AA batteries, 1 small speaker, and two cables one on each end. The two cables can be attached to complete a circuit and the speaker plays a sound. Given ...
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Should I simplify the circuit or use the Kirchoff's method? [closed]

The main goal here is to solve for the values of $I_1$, $I_2$, and $I_3$. Should I use simplification in this circuit or should I divide this circuit into two junctions and apply Kirchoff's method? ...
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What happens to electrons in a cut wire?

what happens to electrons in a cut wire. I know it is dangerous but out of curiosity if there was a power cable cut and connected to the outlet, the electrons would be dispersed in the air when they ...
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How point-contact transistor work?

In December 1947 Bardeen, Brattain and Shockey introduced a device which is considered to be the first transistor. This transistor was point-contact device. So, it used metal-semiconductor junctions. ...
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Did I make an electric circuit with my cat?

This is definitely the dumbest question I've asked, but I'm curious. My cat was resting her head on my left hand while I pet her with my right. Suddenly, my left hand began receiving regular static ...
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How does a capacitor get charged instantly in AC whereas it takes infinite time in DC? [closed]

I have seen when a capacitor is connected to a dc source it takes infinte time to charge, but when connected to ac it takes the potential of the source instantly, probably the approach in the books is ...
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Confused about a question on RLC circuits [closed]

Question: Find the current 'I' after a long time. I got that the answer is 2.66mA, but it is not the correct answer and I don't know why. There is no current on the capacitor after a long time because ...
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Current density in a thin, moving wire

Suppose I have an infinitesimally thin wire (this is of course an abstraction) that moves in space and has a current that changes along the wire (and possibly even in time). The wire is a line in ...
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What is the route the current moves in this circuit? [closed]

What is the route the current takes in this circuit? I can't identify which resistors are in series or in parallel. This is the circuit:
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Which side of the capacitor is at higher potential?

Our physics teacher gave us a simple problem in our class related to the diagram below. The current increases at the rate $4 {\rm As^{-1}}$ and we are to find charge on the capacitor when current is $...

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