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In electronics , a voltage divider (also known as a potential divider) is a passive linear circuit that produces an output voltage ( V_out ) that is a fraction of its input voltage ( V_in). Voltage division is the result of distributing the input voltage among the components of the divider.Consider a point A on a rheostat,or simply take a potentiometer.Now ...


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An intuitive answer could run along the following lines. When any two dissimilar electrical conductors (say, A and B) are brought into contact, the distribution of the charge carriers in A and B at the junction gets altered so as to assume a new equilibrium distribution. This new distribution of charge carriers changes the potential drops from A to air ...


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Point particles as the electrons (which are the charge carriers) move according to Newton's law $\textbf{F}=q\textbf{E}=m\textbf{a}$. Whenever an electric field is present it generates a difference of potential between two points $A$ and $B$ given by its differential form calculated between the two points $$ V_A - V_B = \int_A^B \textbf{E}\cdot d\textbf{s}. ...


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Voltage is a difference in electrical potential in a circuit. You can compare this to a ball sitting at the top of a hill - as it rolls downwards, it moves through a difference in gravitational potential. Because the ball has lower potential at the bottom of the hill, it will roll there spontaneously. The ball will never roll up the hill by itself, ...


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Electricity needs charges particles (or quasi-particles) to conduct. Heat can be conducted with almost any quasi-particle. Diamond is one of the best conductors of heat in existence, and it's because of phonons, ie quasi-particles of lattice vibrations, which are strong because the diamond lattice is strong.


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The electric field around high voltage transmission lines (or "high tension" lines) is extremely high, and can be close to the breakdown threshold of air. That's why the highest voltage lines use multiple (often three) parallel conductors, to increase the effective conductor radius and reduce the peak electric field. Now, introduce a human into that field, ...


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When a motor moves it also acts as a generator and the current trough the windings is given by the difference of the external voltage and the induced voltage. When the motor stands still, though, the generated voltage is zero and the windings will draw the max. current they can based on their DC resistance. In other words, the faster the motor runs, the ...


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Although there are several sources of contact resistance, the main source of contact resistance is the oxidation of the contact surfaces. For the electrical case, the oxides of the materials have a much lower electrical conduction (higher resistance) than the materials, therefore the contact area (that is not cleaned and protected) will have a higher ...


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yes exactly a wire is neutral before it is connected with a battery and will be again neutral cause battery supplies the number of electrons that are flowing in the circuit.


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This is an interesting question whose answer is not entirely obvious. There are many choices of filament dimension which can satisfy the power equations, some of them with bigger diamters and some of them with smaller diamters. However, the real constraint is that all filaments must operate at the same temperature. To make an effective light bulb, the ...


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Power: $$P=VI$$ Ohm's law: $$V=RI$$ Resistance: $$R=\rho \frac{L}{A} $$ These should be what you are looking for.


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When one says that bulb is 100-W, does that mean it is 100-W at 120V, which would tell me the resistance of the bulb? Somehow I have to find the resistance of the bulb which is not given. Recall that, for a resistor, the AC power dissipated is $$P_R = \frac{v_{rms}^2}{R}$$ Assuming the voltage across the bulb is not significantly reduced by the ...


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You didn't add the resistors for the light bulb and cord in series. $$I_{system} = \frac{120V}{R_{cord}+R_{bulb}}$$ Edit: Your math seems to be correct on the resistance of the cord though. I get 0.167 Ohm Now, multiplying out by the current to get power, since the energy drop across the bulb is 100W: $$I_{system}^2(0.167 Ohm) + 100W = ...


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Your answer appears to be correct, bar the lack of any electric charge in your formula. If the applied force is solely due to a cosinusoidally varying electric field at a given position (you can ignore the magnetic component of the Lorentz force only if the charge moves non-relativistically), then so is the acceleration. Integrating this with respect to ...


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Emf of the cell is the measure of potential difference across its terminals which remain even after the current is zero.


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The blade geometry and structural stability is less meaningfull when you have more blades. Means; if you have to to build the blades only from direct cutted materials without any airfoil-shape you have to use more blades. Thanks to Betz law, this doesn't even change the efficiency too much, and it's more or less only a investment cost factor. And, ...


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There is not a truly simple answer that can be posted on a web site in a few minutes to the last question that was asked by the OP: "How is contact resistance explained?" This is easily shown by reading, for example: Heinz K. Henisch. Semiconductor Contacts: An Approach to Ideas and Models. Oxford Science Publications, 1984.


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This is a very interesting question, especially considering the very recent history of scholarship on electrical contact resistance (a term first coined in 1964 by William Shockley, one of the inventors of the transistor), as well as thermal contact resistance. For the following explanation, I will use this research paper on electrical contact resistance ...


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Another term is thermal resistance, This is incorrect. Thermal resistance is something that prevents heat flow. It is an entirely separate concept from electrical resistance. How is contact resistance explained? To obtain very low resistance in a material like most metals, the electrons must be delocalized from the individual atoms, and free flow ...


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Because so many different power generators are connected to the same mains circuit, it is extremely important that all generators maintain the same phase (and thus frequency) of the power supply. This makes the 50 Hz (or 60 Hz, depending on what continent you are on) a rather reliable reference signal. In this website the question of mains power stability ...


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Your fillings are either gold / palladium inlays or silver-mercury amalgam. The composite or enamel fillings don't apply here. Welding fillings together will require that you have fillings in opposing teeth. It is certainly possible to weld metals together with a brief electrical current - it's done by robots in car factories every day. However, it requires ...


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This is my last question I swear. I've done a lot of research on plate backing magnets and understand how the field lines in one direction is amplified, and I have learned a lot from what you have taught me, so I don't want you to think I'm ignoring everything and trying to make up laws of the universe. But if I had the dual stator design mentioned, what ...


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Note: For practical alternator designs for gaining experience you are MUCH better off looking at websites with construction examples that seem to meet your needs than trying to push the limits of what can be achieved and (typically) failing. You can leap straight into finite element analysis and more, but actually building something If it is only the ...


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The charger accepts one voltage as its input, and produces another voltage as its output. This could be done with a transformer or any number of other conversion techniques - for example, in a switched mode regulator the voltage is connected very briefly to charge a capacitor, then disconnected again. It keeps repeating this to keep the output at the right ...


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Because air in some way like a monument wall for electricity , imagine if you have an air bubble in closed volume in solid wall and the tension of pressure in this bubble is increasing then when the tension will be big enough the pressure is crack the wall, so crack is appear and to understand deeper we need to understand that this wall have structure like ...


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Lightning branches so that it can reduce the resistance of the path it takes to the ground. As you know, when you attach two identical resistors in parallel, the equivalent resistance is lesser than that of the two in series. Branching essentially does that. It creates more and more parallel paths by which the electrons can flow, thereby reducing the total ...


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Can electrons reflect light? Yes. Like CuriosuOne said, electrons are shiny. I kid ye not, google on electrons shiny. Metals are shiny because they have free electrons. Check out this question about the colour of metals, where Ali said a metal is are silvery because it "reflects all wavelengths specularly (more or less)". Also see this article by William ...


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The temperature of the circuit can probably be crudely modeled by assuming that you have two channels: one for heat absorption, and one for heat loss. Heat loss Suppose you have something like a light bulb. The hot filament loses heat via radiation and conduction. Let's focus on radiation. The rate of heat radiated by an object of temperature $T$ depends ...


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First, do not put them "in series"! Each is powered from the mains ie they are in parallel. Second, earthing is typically applied to any external metalwork that anyone might come into contact where there is any danger of the live coming loose and touching that metal. Think worst case fault conditions. Finally, the fact you have to ask these question means ...


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DC current is organized as following: positive potential applied to one end of the wire, negative potential applied to the other. Electrons move from one end to another with some speed. If you have one electron in vacuum and electric field from A to B, then there will be force acting upon that electron due to $F=eE$. Movement should happen along line ...


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The electricity doesn't go anywhere; it's just moving electrons, where the electrons are just part of the material. As to the "ringing", it isn't due to the momentum of the electrons, but the collapsing of the magnetic field built up by the moving current. The field collapses, causing an electric field (voltage higher at one end than the other). The voltage ...


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First, if you ground a magnet into powder, then the tiny resulting magnets would rearrange themselves into the lowest possible energy state, and that's with each N pole matching with an adjacent S pole. Yes, you could guess you'd get one long line of magnetic particles lining up into a long thin magnet, but then the next line over would line up in the exact ...


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You should look at an electric circuit a like a river or a water slide attraction in an amusement park (see my little artist impression below). The resistors are the steep parts: that's where the potential energy is lost. The wires are the horizontal parts, so there no potential energy is lost. But as the water is already moving, it doesn't stop moving in ...


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Technically you are correct and there is a voltage drop with distance but since the voltage drop is current * resistance and your resistance on a PCB track is usually measured in the milliohms it's ignorable unless your doing something really hairy with LOTS of current or ultra sensative.


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Are you speaking specifically about currents in wires? If you look at (the simplest version of) Ohm's law you will see that $\mathbf{J} = \sigma \mathbf{E}$, where $\sigma$ is the conductivity (technically it's a tensor, but we'll assume a constant scalar for now). In this case, $\eta$ = $\sigma^{-1}$, which is the resistivity. Thus, we can show that ...


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Rather than call it "electricity", I would prefer "current". But you are correct. For a disconnected segment, the amount of time the current will continue to flow depends on the capacitance, the resistance, and the starting current. For for your average "disconnected wire", the capacitance is quite low and resistance is such that there will be very little ...


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Looking up "what happens when lightning strikes a house" on google (it is a .php file so I had to use printscreen) See also this youtube video. So yes, avoid taking a bath during a close by storm. Have a look at this answer What will happen when lightning strikes on the surface of the deep sea? which has some numbers of the energy in a strike. By the ...


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...Just in case you are asking a more basic question than the other answers have assumed: You might be operating under a common misconception about how electricity flows in a conductor by thinking about it like water in a pipe. Obviously, if you have an open-ended pipe with water in it, and you spin the pipe around, water goes flowing out. Electricity ...


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The electrons are charged particles and will experience a Lorentz force if the conductor is moving orthogonal to a magnetic field, causing one part of the conductor to be more charged than the other. If the conductor is uncharged and spinning, it will exhibit the Barnett effect, but this has more to do with other properties of the body. You may be thinking ...


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The lightning only 'sees'positive and negative charges. If the storm clouds are negatively charged then they drag a positive charge along the surface of the ocean. When the charge reaches a certain capacitance a lighting strike will neutralize the potential. Like some people, the strike follows the path of least resistance; which is usually the highest ...


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I have seen lightning hit the middle of a sea lake. ( very happy I had not gone swimming). The water did not boil enough to be observed at my distance, about 500 meters. No dead fish were washed out. A boat or a head in the sea water will become a focus for the upward streamers that will join the downwards leaders and form a path for the energy of the ...


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I guess the answer you are looking for is that the electric field propagates at the speed of light. Suddenly add a voltage source to a complete circuit and the electric field will spread at the speed of light $c$. Depending on how far away a specific electron is in the circuit, this electron will soon feel this electric field and then immediately react to ...


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Electrons do not "decide" which path to take in any meaningful precise sense (they don't take any particular path at all unless an interaction fixing their position takes place every step along the way), hence there is no time span in which that decision is made.


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Consider, lets say, a wire of cross sectional area $A$, with charges (each of the same magnitude, $q$) flowing through it. If you consider a section of the wire of some length $x$, the volume of this region would be $Ax$. Because $n$ is the no of charges per unit volume, the charge in this region would simply be $q(nAx)$ ($nAx$ is the number of charged ...


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Current is defined as the rate at which charge flows through a given surface: $$I=\frac{\mathrm{d}Q}{\mathrm{d}t}$$ and in a circuit this surface is any cross-sectional area (perpendicular to the flow). You can often simplify that to charge through a cross-section per unit time and write $I=\frac{Q}{t}$ Answer to the comment: Another but equivalent way ...


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It's the amount of charge flowing through a surface per unit time.


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Intuitive explanation: The charges want to get as far away from the other charges as possible. If you are at a party with lots of people, and you don't want anyone next to you, you go stand in the corner. The tighter the corner, the fewer neighbors you will have. Similarly, charges try to distribute to have the same potential - that is, the sum of the ...


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Say you had two equal charges, $q$ a distance $x$ apart. $E=kq/r^2$ in general. You are right. The electric field can be defined as the force per unit charge. So a $100N/C$ field is one where 100 newtons of force would be exerted on a 1 Coulomb charged particle. so if we find the field due to the two particles right at the middle of $x$, at a point $x/2$ ...


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The problem is that the two calculations have hardly anything to do with one another - so it's no wonder you don't get the same result. The electron volt, as you say, measures the work you need to move an electron across a potential difference of one volt. On the other hand, if you want to calculate the mass of an electron using $E=mc^2$, what you need is ...



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