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Questions tagged [electric-circuits]

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

Electrical circuits are describable as having current flow in a complete loop, produced by some other form of mechanical, chemical, optical, nuclear, thermal or another energy. Man-made circuits being most often discussed. Electrical circuits permit the expedient delivery of energy from one location to another and/or from one type of energy to another. Anything that can be described as using electrical charge, in an electrical conductor, as a means of energy transmission, could fall into this category.

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Why do electric motors draw current even when they are not moving?

After testing electric motors, I realized that these motors draw current even when they are not moving. I do feel that these motors are trying to move, but they are not really moving, in the end. Why do these motors draw current even though they…
user29157
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Can an arbitrary RLC-circuit network have non-minimum phase zeros?

I am working with certain input-output maps that can be thought of as large RLC-networks. I thought maybe this might be a place to get some thoughts/ideas/answers. My basic question is, given some large connected RLC network (all linear and ideal…
1yen
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Why does breaking one bulb on a string of Christmas Lights cause all the rest to break in some lights?

If I break one bulb on a string of Christmas lights, or the filament goes out, then all of the rest seem to stop working. Why is this? However, I've also seen the opposite happen in some newer lights -- when one breaks, the others stay on. What…
Justin L.
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$V=IR$, isn't it missing something?

So I know that $V=IR$ works for circuits, but for the case of an arc-before the arc jumps, there is a potential difference, but no current, but there isn't infinite resistance is there? I don't understand how to compute a finite resistance for an…
user24082
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Why does current need a closed loop to flow?

My textbooks at the moment don't really explain the underlying theory of circuits. All I do is apply the rules I was taught when I solve these problems. I don't get why electrons need to have a closed loop in order to want to flow. The circuit I'm…
DLV
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Why do current-carrying wires heat up?

Obviously wires heat up too, but why do they heat up? And for the same reason, why do we get electrical burns?
user24082
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If there is a potential difference between the ends of a battery, does it mean that there is always an electric field?

First of all, I am really sorry if this question is wrong. But, I thought that this would be the best place to ask this. Here is what I am thinking: Batteries promote flow of current in a circuit due to the potential difference they create, or in…
codetalker
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How can I use the Kirchhoff Laws where there’s a ground connection?

Normally we use the Kirchhoff Laws on “loops” in the circuit and to form loops, “electronic components” are connected to wires on both sides. However, with a ground connection there’s only one side connected to the circuit by wire. This makes them…
youthdoo
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Two Electrical Switches Control the Same Light

I have a stairway light in my house. There are two switches, one upstairs and one downstairs. When both switches are in the "off" position, the light is off. When one switch is in the "on" position, the light is on. When both switches are in the…
Peter Ye
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Current in a purely capacitive circuit

By the phasor method for AC circuits, we know that the voltage in a capacitive circuit lags the current by $\frac{\pi}{2}$. My book says that the current in a purely capacitive circuit is maximum when the instantaneous voltage is 0. How can this…
Kunal Pawar
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Why is there a voltage drop across things when no current is flowing?

If you have an electric circuit with a 12V battery in series with an open switch and a resistor, the voltage drop across the open switch is 12V. But this doesn't quite make sense to me. If there is no current, why does Ohm's Law not apply giving me…
user1551817
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How to distingush the $\Delta$ circuit from the $Y$ circuit by external measurement?

We know how to calculate the parameters of a $Y$ circuit in order to get its $\Delta$ counterpart, and vice versa, as well. My question is as follows. Assume that we have an equivalent pair of a $\Delta$ and a $Y$ circuit both locked in boxes. Is…
zoli
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Do light dimmers save energy and lower your electric bill?

Or do they just capture the incoming energy and turn it into heat at the unit and save you nothing?
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Detect Breaks in Mesh Circuits

PS: I will mess up a lot of terminology throughout the question. Anyways, I want to build a circuit which is in the shape of a mesh, something like a table and subsequently detect whenever there is a break at one of the nodes (i.e. the intersection…
nerdcortex
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Birds and cables: how is the potential difference between two diff. cables established?

The common explanation of why birds don't receive a shock when standing on high tension cables is that there needs to be a considerable potential difference between both of his feet for him to receive the shock. I understand this for a single cable,…
DLV
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