Questions tagged [electric-circuits]

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

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State excitation table using T flipflop of a sequence detector circuit which gives an output when it detects the sequence 0101?

State excitation table using T flipflop of a sequence detector circuit which gives an output when it detects the sequence 0101? Overlapping sequence are accepted
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How to apply Kirchhoff's rules in a circuit with Voltmeter? [closed]

I was trying to apply Kirchhoff's rules to find out the reading that will be shown by voltmeter. But then, I realized that the current coming out of the voltmeter arm will be zero (assuming infinite ...
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Why doesn't energy supply rate equal the dissipation rate for electrical energy transmissions?

I was recently reading an example which showed that the average rate of energy dissipation due to resistance of the wires that are used in the transmission of electricity from a generator is not equal ...
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How to calculate equivalent resistance using Circuitlab [closed]

I'm a beginner at Circuit lab and i tried to calculate the equivalent resistance between node 1 and node 2 but didn't know how so if there's anyone here who's familiar with using Circuit lab i really ...
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Complex Resistance Circuit Problem.. Finding Equivalent Resistance [closed]

I have a doubt regarding this q. how should I approach this q, I want to calculate equivalent resistance.
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Applying KVL to a circuit with only a battery and a capacitor

My textbook states that KVL can be applied to a circuit with only a battery and a charging capacitor. According to the textbook then, the voltage across a capacitor always equals that of the battery. ...
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Why charges don't lose potential in a resistance free loop?

If a battery to a current was like the gravity to a massive object, so the potential rise in the battery is like lifting the massive object above earth's surface, so when charges get closer to the ...
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How does the electromagnetic field behave in a complex circuit when first energized? Such as in a computer CPU booting up

From what I understand in the case of a simple circuit, the electrons in the circuit wiring are steadily excited, i.e. energized, in a fairly complex way by the external energy input, as the energy ...
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What causes the behavior of the increasing transient current in a circuit with an ohmic resistor?

Why does the current increase from zero to its steady state value in a circuit with a battery and an ohmic resistor, as opposed to initially reaching a very high value and then decaying down to the ...
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How to properly wire a power supply to a remote control [closed]

I have a remote control for an RC helicopter that I want to hook up to a power supply. Each battery takes 1.5V and I need 6 total. The power supply has a positive and negative terminal. I'm not very ...
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Imaginary numbers in AC circuits

I've heard/read multiple times that "the use of imaginary numbers in ac circuits simplyfy calculations". My questions is: how is the calculations simplified? (exaple calculations?) And what ...
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Is voltage the integral of electric field or energy per unit charge? [closed]

See this video on the debate about the definition of Kirchoff's voltage law. See around 8:15. The difference in views seems to hinge on the definition of voltage. In one case voltage is defined as $$ ...
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How do charges in a circuit know how much work to do on a component?

So I'm a high school student learning physics so I don't really know much about circuits yet. Our teacher said that in a circuit, electrons don't really flow through the circuit and that there's more ...
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Reverse polarity of cells connected in series and net EMF [closed]

When 2 cells are connected in series with reverse polarity, the net emf of the combination is difference of individual emfs, but clearly this is not the case practically, since cells connected in ...
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Physical significance of circuit eigenvalues and eigenvectors

When solving a DC circuit (say, with resistors and voltage sources only), we can use Kirchhoff's laws to get a set of equations in the currents: $$ RI=V, $$ where $R$ is a matrix relating to the ...
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Calculating the rate of heat dissipation in a tungsten filament

The formula for the rate of heat dissipation in a resistor is iR^2 for an Ohmic resistor. If this Ohmic resistor is replaced with a tungsten filament, which has a resistance that varies linearly with ...
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Electric Current Misunderstanding

There are examples that describe electrical potential as two oppositely charged plates facing each other to make an electric field. They place a positive test charge close the positive charged plate ...
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An electric motor operates on a 50 V supply and a current of 12 A. If the efficiency of the motor is 30% what is the resistance of winding of motor? [closed]

This is not a textbook question,i want to understand why it would generate two different values? and I cannot do that without invoking some form of numerical value in my question Ok so I get that the ...
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Why is mean free time inversely proportional to the electric field strength?

I was looking at the mean free time formula in the Drude model, and realized that it is proportional to 1/E. I am having trouble grasping this idea. I am aware that in practical cases the drift ...
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Electric current through the resistor of an AC $(L)RC$-circuit

I have a question regarding more complex circuits. For the sake of simplicity, suppose we have an AC source with an alternating voltage $U=U_0\cos{(\omega t)}$ and the angular frequency $\omega$ tied ...
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What was the first use/cite of "Watt's law"?

Yesterday I saw a reference to Watt's law being used for the power formula P = V I. It's been over 40 years since I learned my basic electrical engineering fundamentals and this is the first time that ...
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KVL in short circuit with 0 resistance [duplicate]

According to KVL, $\sum \epsilon = \sum RI$ in any closed loop. However, in an ideal circuit with no resistance, R is $0$, and hence $\epsilon$ must also be $0$. Does KVL not apply in this case?
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On the analogy between RF cavities and parallel RLC circuits

Every superconductive radio-frequency cavity can be seen as a parallel RLC circuit, as shown in the picture below: The thing is every parallel RLC circuit acts like a band-stop filter: at the ...
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Derivation of the potential difference across a resistor

I am trying to understand how the voltage drop across a resistor comes about in a DC circuit. I have no concerns over the relation described by Ohm's law: the current through a resistor will be ...
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Kirchoff analysis in faraday law for RL circuit

Faraday law state that $$\epsilon_L=\oint \vec{E} \cdot d\vec{l}=-\frac{d\phi}{dt}=-L\frac{dI}{dt}.$$ So by kirchoff's analysis, isn't the equation would be like $$\oint \vec{E}\cdot d\vec{l}=0-IR+\...
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Deriving an lumped element LC circuit as the limit of a resonant cavity mode

In principle, an LC circuit is just a degenerate limit of an electromagnetic cavity, where the frequency $\omega_0$ of the resonant mode is much lower than the inverse size of the cavity. As a result, ...
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Solving an ODE numerically with different units

I am simulating a leaky integrator with $R_m = 10^8 \, \mathrm{\Omega}$ and $C_m = 10^{-10} \, \mathrm{F}$ with an input current of $I_{in} = 10^{-9} \, \mathrm{A}$ for $0.1 \, \mathrm{s}$: $$C_m \...
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Are we always allowed to treat an inductor as a battery with the same voltage?

When there is an induced emf, Kirchhoff's Loop Rule no longer is true, because electric fields are nonconservative when there is an induced current, as stated by Faraday's Law: However, I have seen ...
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Alternating current changing direction [duplicate]

As we all know AC is is supplied to our homes. As Ac switches direction constantly why only the live wire is hot and there is no negative cycle in nuetra
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What happens if ONLY one terminal of a cell is connected to a piece of conducting wire?

I've learned that current will flow to bring the potential of both ends of a wire to the same value if there is a difference in potential between them. Consider a cell of emf, , and negligible ...
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Where is the excess energy going to when a solar inverter is operating a photovoltaic (PV) panel away from the maximum power point (MPP)?

The MPP is the maximum power point of a solar panel and a PV inverter will typically try to find this MPP to yield the maximum energy ouput. But sometimes it might be neccessary to operate the panel ...
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Connecting only one plate of the capacitor to the positive terminal of a battery [duplicate]

Suppose that the positive terminal of a battery is connected to one of the plates of the capacitor, and the other plate isn't connected anywhere. The other terminal of the battery is connected to a ...
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Dependence of work done by battery on circuit elements

The formula for work done by a battery is QV, where Q is the charge transferred by the battery. The battery maintains the potential difference between its terminals through oxidation and reduction ...
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Transport of energy in DC current

In alternating current (AC), electrons barely move a few centimeters along the conductor, with the usual frequencies and intensities in electric lines. That fact, together with Maxwell's equations, ...
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Parallel and perpendicular component of electric field

We know electromagnetic wave is moving along propagation direction and electric field, magnetic field & propagation direction are perpendicular to each other. Then please tell me what is the ...
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Why don't the ends a switch function as a capacitor?

I was recently reading about one capacitor being used to charge up another capacitor. In this example, a capacitor is charged by a battery, and then the battery is removed. The charged capacitor is ...
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How to find current density given resistor, and voltage, using Ohm's law in this case?

I was wondering about how to find current density, given a resistor and an electromotive force. resistor's data are: resistivity = $\rho$, length = $l$, and cross sectional area = $A$. resistor = $\...
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How do resistors work?

Why is the current before and after a resistor exactly the same? I understand the same amount of charge that enters the resistor leaves, but current is defined to be charge per time. The way I ...
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Measuring voltage

Recently I was playing around with this circuit simulation, and I found that if I had a circuit with just a lightbulb and cell, then If I were to measure the voltage between the bulb and cell it gives ...
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Voltage in circuit

The way I understand voltage is the following: Its a measure of energy given to charge carriers in a circuit. Its a measure of potential difference, and it is the work in joules required to move 1 ...
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How do we assign value of EMF to a cell?

There are cells of different emfs like 1.5 volts, 2 volts etc. My concern is when we can not calculate the individual potential of any plate, or the potential difference between the plates by any ...
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Which electrons kill you during electrocution?

I understand that there are three velocities in play in a circuit (I haven't studied Physics past high school so give me some rope) v1: the velocity by which the electrical field propagates through ...
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Can an electron flow without potential difference?

Have seen that a positive charge flows from higher potential to lower potential, the direction of this flow is opposite to the flow of electrons, my concern is if an electron is thrown, it moves and ...
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In electrochemical sensing, why do molecules binding cause changes in current?

From my limited understanding in electrochemistry, a set of electrodes are biased at a given potential and when there is a chemical reaction(antibody-antigen binding for example), a subsequent change ...
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How does DC circuit deliver energy?

I don't understand how energy is being transferred in a DC circuit. For example here I have a simple circuit powered by a constant voltage. Some form of energy is being transferred from the source to ...
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The criteria for zero DC resistivity from Kramers-Kronig relation?

While studying introductory superconductor theory, Neil Ashcroft came up with a criteria for zero DC resistivity as a following: $$\lim_{w→0}w\cdot\rm{Im} \ \it{\sigma(w)}\neq\rm{0}$$ And this must ...
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Voltage across points when going in reverse direction across cell

When charging a rechargeable cell, an external power source pushes a current from the (+) to the (-) terminal of the cell. Consider a cell of emf $3$ V and internal resistance $0.80 \Omega$ that's ...
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Does current flow inside a battery?

When connected in a circuit, does current flow inside a battery. If yes, in which direction?
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What happens to a non-conductive material in a circuit?

I recently encountered an electric fence in the countryside. The fence was made from wooden poles in ground which were connected by 3 wires from top to bottom. At one of the poles, however, the middle ...
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Does potential inside a wire is different at different points?

When wire is connected to a battery with potential difference across the terminals of the battery 'V'. Now we know the potential difference accross the wire is also 'V'. My questions is do the ...
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