Current is a scalar quantity. In Watt-less current, we divide current into components like vectors. Moreover, when AC current passes through inductors or capacitors, we put a vector sign over current. Can anyone please elaborate?
48070
Current has both magnitude and direction. As per the definition of vector , current should be a vector quantity. But, we know that current is a scalar quantity. What is the reason behind it?
45705
I'm confused with this definition of displacement currents within capacitors via Wikipedia:     However it is not an electric current of moving charges, but a   time-varying electric field.   It's a time-varying electric field, but there isn't any actual flow of current, while at the same time... it produces a magnetic field. It's counter-intuitive.  If air was in the center between the plates, it's possible to have some "current flow" due to atoms within the gas molecules, likewise, for a dielectric.  Yet, displacement currents aren't considered "real/free" current. Could someone clarify this confusion for me.  How significantly different are displacement currents from normal/free currents?
48045
When we have resistors in series, the current through all the resistors is same and the voltage drop (or simply voltage) at each resistor is different.  Question 1: It is fine that voltage drop (potential drop) across each resistor is different because each resistor offers different resistance (suppose). but how is the current through each resistor same? If we have resistors of different resistance, shouldn't the current be different through each resistor?  Similarly, when we have resistors in parallel, the current through each resistor is different but the voltage drop at each resistor is same.  Question 2: Current through each resistor is different because resistance of each resistor is different (suppose). but how is the voltage drop across each resistor same here? Shouldn't the voltage drop at each resistor be different because each resistor offers different resistance?
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?
1365
I understand all the concepts of what voltage is using all the analogies but some things related to the drop of voltage across a circuit confuses me.   If I had a short circuit and attached a voltmeter I would get a potential difference reading of 0 volts. How is current then going through the wire if it is 'X' volts at any point in the wire? Let's say I have a DC 9V battery with a load in the middle. I read somewhere (probably mistaken here) that the voltage drop in this situation must be 9V or rather, that the sum of load resistances must be equal to voltage of the source. I mean, there is a variable amount of resistance to each load so at the base of the load I might have 9V and at the end of the load I might have 5V with a 4V potential difference.
55888
According to , if there is a potential difference, $V$, across a resistor then there is a current, $I$, flowing through it.   Since we assume that points along the connecting wire are at the same potential, how can current, $I$ flow between points at the same potential, $V$?
2043
Current is the amount of electrons passing through a wire. Can we say that voltage is the speed of those electrons?
42481
I understand that when you put Resistors in parallel the resistance decreases, my question is why does this actually happen? What causes the Resistance to decrease? When Resistors are in serial, their Resistances are added, why when we put them in parallel do the Resistors resist less current? I don't understand how that's possible?
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What's the point below which electrical current is generally considered safe for "casual" human contact?  Is either voltage or amperage more "dangerous" (e.g. high voltage / low amperage vs. low voltage / high amperage), or is the only consideration the total current?
101022
Sinking and sourcing current refers to current going into and out of the MCU (respectively), right? If you configure a GPIO pin as an output, why would current ever go into the pin (since it's configured as an OUTPUT)? I suppose it depends what the output circuit looks like, if it's tied to the voltage supply rail or ground... maybe I just answered my own question...?
64865
I know that this question has been asked many times before, and I have read over several of the threads asking this question, but they do not include the gripe I have with my problem of understanding the difference.  As I understand it, voltage, V, (also called electromotive force, EMF) is essentially the "wanting" of electrons to push away from the negative terminal and to want to go to the positive terminal to eventually balance out the charges and create a net neutral charge. This is done through a conductor, like a wire, between the two terminals. The movement of electrons caused by the attraction of the charge from the negative terminal to positive is the current, I.  Now, as my textbook defines it, voltage is the amount of energy, E, per unit charge, Q. Current is defined as the amount of charge, Q, passing through a point in the circuit in a unit time, t. Current is determined by voltage, as is also stated in Ohm's Law (i.e. if voltage rises/falls, current rises/falls, if resistance remains constant). So then, if energy is lost in a resistor, why does current through the resistor not change? Shouldn't the current go down if energy is lost? Or is it that energy is determined by something within the voltage source (e.g. battery) that is not related to charge?
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.
104667
&quot;The effective value of an alternating current is that current which will produce the same heating effect as an equivalent direct current. The effective value is called root mean square RMS value.&quot; What is that &quot;heating effect&quot; stated in the sentence?
119375
I am an electronics student, and I was set some homework online. I am not having trouble with the question itself but the theory. It says that the current through the resistor is the same as the maximun current that the diodes can safely handle, but as you can see, there are (\$V_{out}\$) volts being dissipating to the right, and a minimum required current going through the diode to maintain consistent voltage.  The thing is, how could the current through the resistor be the same as the current through the diode, as \$Voltage=J/C\$, or, joules per coulomb, so that means there must be some energy carried by the coulombs, and ultimately, some electrons. But then this is contradictory, wouldn't the current going through the resistor be the total current, the current dissipated to the right and current through the zenor? Or... is it that there isn't, then, any current passing at \$V_{out}\$? and it doesn't represent voltage being dissipated? I cant wrap my ahead around it...
43576
It took me a long time to understand that current is constant throughout the circuit. And now I am stuck at one last thing: The speed of charge. Here is what I am thinking:  Current is defined as quantity of charge passing through a point at a given time, and from this we can deduce that current is constant throughout a circuit. But, if this is true, then wouldn't the speed of charge through a resistor be increased? Let us think about an analogy, water flowing through a pipe. Suppose water is flowing through a broader pipe(analogous to a less-resistance wire), and  a greater quantity of water can flow past a point because of larger cross-sectional area. Now, suddenly water encounters a smaller pipe(analogous to the resistor). So, less quantity of charge can flow through it because of less cross-sectional area. But, if the volume of water flowing in a time $T$(analogous to current) is same, won't the rate of flow of water in the narrower pipe(the resistor) be more?  I am asking this question because while seeing some answers for the question that "Why is current constant?" , I saw some people saying that speed of charge slows down a bit through a resistor, which seems incorrect to me.
43764
I have a simple circuit consisting of 2 ideal voltages sources (each 5V) parallel to a resistor of 5 ohms. The current along the resistor is 1A, right? But by applying the superposition principle (i.e. considering individual sources), I am not getting this result. Am I doing some blunder?
79583
Please don't state the obvious that nothing is a perfect constant current source.  And please do not give examples of how to create them from components.  I looked at this  which stated the obvious - that you can not have a perfect current source.  So when I say constant current source, I am not referring to the mathematical concept used in circuits, but "natural" components that provide a close approximation to this. Key word is approximation.  A bit of research pulled up one interesting example which was a solar cell.  Is this a valid example?  A google search pulls up a similar Quora question . Which gave the example of a solar cell.  This is a more technical site and I was looking for a more engineering answer not a mathematical or laymen's answer.  Thanks.