AC current does pass from a capacitor. But DC current does not pass through it why?
120424
We know that in circuit capacitor block the DC current and pass AC current. My question is how a capacitor block DC and pass AC?
74282
I've been taught that a transformer only works with AC, however I see that in power converters, it is rectified to a DC voltage before going to the transformer. How does that work?  If the rectified AC waveform is now DC, how does it pass through the transformer? Is the rectified signal still good enough for the transformer, because it still has a fluctuating component in it, just not negative anymore?  So for example, if I have a 230V mains (with 10% fluctuation) going into my rectifier, the output DC level will range from 293V to 358V. Is this fluctuation/AC component good enough to pass through the transformer?
89260
If we connect an AC source with a pure inductor when AC source is going through 0 volts we get the following graph of the voltage and current.  There are few things in the graph about which i am confused.  In the first graph/diagram "A" of the picture which shows the voltage when it starts to flow and the corresponding current, the current doesnt seem to be lagging behind the voltage by 90 degrees. What is the reason behind that? Is the statement "current lags behind the voltage in an inductor BY 90 degree" is valid just for the steady state voltage shown in graph "B"?  Second confusion is that for the first half cycle of the voltage in graph "A", current is rising both for increasing and decreasing voltage. How is this possible that current is rising in the inductor for both increasing and decreasing voltage?
100149
In the following image:   Why can't current flow across the following wire? It's a simple question, but I've kind off always wondered.  Thanks!
76354
I'm struggling to understand the purpose of the resistor circled in red, I know it has something to do with DC biasing and the feedback on the circuit (as the capacitor will cause AC bypass). But I'm struggling to understand the exact circumstance where this would be needed. Is it a change in supply voltage, or change in transistor beta? And the exact mechanism that would cause the resistor to solve the problem.
107456
Two or more capacitors are said to be connected in parallel if each one of them is connected across the same two points. In a parallel combination of capacitors potential difference across each capacitor is same but each capacitor will store different charge. Why is this true? Why is the potential difference across each capacitor in parallel the same and why will each capacitor store different charge?  Also, in series, why are Potential difference across each capacitor different, while charge is the same?
42375
If the live wire in above illustration touches to the metal case, a high short circuit current will flow to the earth through the safety earth wire and the fuse will trip.  Now imagine a 9V battery staying on a wooden table. If now its plus terminal is tied to the earth through a wire almost no current will flow.  Above two points shows that it is not the case that the earth is a reservoir that sucks all electrons, but simply current needs a loop to flow.  In the battery case it is obvious that there is no loop because the negative terminal is floating.  But what is the loop in the first AC case? Is that the AC generator star connection? Can you draw this loop to illustrate better?
71646
So can anyone explain me how the collector voltage(V (output)) will vary with variation in base current with respect to the following figure?         &ndash; Schematic created using
123028
What exactly would happen in the ideal case where a capacitor were to discharge into a wire with zero resistance?  Like in here:  There is still charge on one plate of the capacitor, which will try to go to the other plate to make $\Delta V = 0$ across the capacitor, so there has to be a current $I$.  But as more charge goes to the other side of the capacitor, the more repulsion these will cause to more coming towards them. So I am assuming current cannot just be constant?  I am starting from $$ I = C \frac{dV}{dt}, $$ but I know neither $V(t)$ nor $I$.
83830
For my project, I'm trying to work with the principle of electrovibration. This principle is about simulating textures using low current electricity on an insulated conductive surface ().  In order to do this, I will be experimenting with generated AC signals of 80 to 160 Vpp at 60Hz to 400Hz. I will do this by using an DC - AC converter, usually used for EL lamp applications.  My only concern is how to limit the current coming from the converter. Are the techniques for limiting AC current the same as DC, by using a simple resistor? Or is it, as I expect, more complex?  I need to limit the current to 0.5mA, for safety reasons.
73717
I have been looking in to alternating current and I am confused. If the voltage reverses doesn't the flow of electrons also reverse? I am aware of another fair answer on this site . That answer, however, confused me just a bit. I gathered that the electrons do not per se "flow." Is this true? How is the electrical current moving?
59450
Is it the current you have to drive in the input to get a specific, defined voltage at the output? And don't the currents cancel each other when applied to both inputs?
41588
So I found this 9V 1A AC power supply laying around and decided to make a DC source.  I rectified and added a capacitor to make things a bit even. After adding a capacitor my voltage boosted from 9V to 14V. Can somebody explain why this happened for me? (maybe this has something to do with frequency?) According to theoretical graph I should get aprox the same voltage even after adding the capacitor. And voltage varies depending on how much capacity the capacitor has (aprox. from 12-16V). Maybe there's some sort of equation to determine the actual output voltage depending on caps? It would be great to get 12V out of this thing.   P.S.: Personally I find this boost weird because this circuit doesn't have any switches and coils to boost the voltage, so I need an explanation, thank you in advance!
16161
Kirchhoff's Current Law states that the net current through a node is always 0. AFAIK this derives from conservation of charge principle. My question is, is KCL applicable to any electrical component? For example is it applicable to transistors, integrated circuits, etc.  My thought is that it should be applicable, because otherwise, the component would be accumulating charge over time, which I presume is not a stable or desirable (in general) condition. Another possibility would be that the component would be "leaking charge". For example, the component would be "throwing charge into air" etc. In this case, the component is not accumulating charge but charge is being moved out of the circuit. I guess this doesn't happen in general as well.  So my question is, is Kirchhoff's Current Law is applicable to any circuit element? For example, if I add up the currents through pins of an integrated circuit at a given time by taking current directions into account, will I get 0 amperes? Similarly for any other circuit elements. Are there any cases where the net current is not 0 amperes?
59261
I understand that inductor current and capacitor voltage cannot change abruptly, but can inductor voltage and capacitor current change abruptly?  I have a feeling the answer is no but I cannot explain why.
101640
On RC circuit, capacitor discharges when the voltage supply is removed.  But I've learned that the net electric field outside a charged capacitor is zero by gaussian surface and gauss law.  I don't understand the mechanism. Shouldn't be there an electric field in order to make charge flow when discharging happens?  Is there an another mechanism?
62375
I'm curious how much current it is safe to pass through a 0.1" pitch pin header. I'm sure it will depend on the gauge and stranding of the wire attached to it as well, but assuming that is not the limiting factor how much could be safely passed?