# Questions tagged [voltage]

Voltage is the unit of measurement for electronic potential, from one point location to another.

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### Relation between Electrostatic Field and Electrostatic Potential at infinite

While reading about Electrostatics Potential I had a question about the relation between electrostatic potential and electrostatic field. As we know that $E = \frac{1}{4\pi\epsilon_0} \frac{Q}{r^2}$ ...
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### Why is thermal noise Gaussian distributed in voltage, but Rayleigh distributed in amplitude?

This is a follow-up to a similar but distinct question I recently asked. Background. Consider an ideal antenna. For ideal polarized thermal noise treated as a sum of random, complex phasors, ...
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### Will there be a current through resistor $R_5$? [closed]

Will there be a current through R5 ? If you join two separate circuits with a resistor will current flow through the resistor?
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My TB gives the following formula of emf of cells in parallel: $$\frac V{R_{eq}} = \frac{V_1}{R_1} + \frac{V_2}{R_2}+\frac{V_3}{R_3}+...$$ where $\frac 1{R_{eq}} = \frac 1{R_1} + \frac 1{R_2}+\frac 1{... • 170 0 votes 0 answers 12 views ### Behavior of the current in a purely capacitive circuit during the two quarters of a half cycle For a purely capacitive circuit driven by an AC source,$v(t)=V_0\sin\omega t$, the current through the circuit is given by$i(t)=I_0\cos\omega t=I_0\sin(\omega t+ \pi/2)$. A. For the first quarter of ... • 9,473 1 vote 1 answer 38 views ### Energy of a Continuous Charge Distribution I had a question regarding the derivation for the following expression of the energy of a continuous charge distribution $$W=\frac{\epsilon_0}{2}\int_\text{all space} E^2d\tau$$ To get this result, we ... • 33 -3 votes 1 answer 82 views ### Electricity Paradox Imagine that you has a large electric potential difference across two parallel branch's in a circuit. One branch has zero electric resistance, and the other branch has a load such as resistor. Which ... -3 votes 2 answers 72 views ### Why dose current only take the path of zero resistance in a parallel circuit? If a resistor in placed in parallel with a wire of zero resistance the current only flows though the path of zero resistance. What stops the the current from flowing thought the resistor? Also how do ... -1 votes 2 answers 36 views ### Electrical Current Series Circuit Why is the current within a series circuit the same through all components? If we had two resistors one with 6 Ohms of resistance and the other with 2 Ohms, shouldn't the current be greater at the ... 0 votes 0 answers 10 views ### The positive and negative terminal of a coil when the flux through it changes [duplicate] I want to know what will be the positive terminal and the negative terminal of a coil,when the flux is changing through the coil. I know about the direction of the induced current, but wondering what ... 0 votes 1 answer 16 views ### Induced e.m.f and induced current in a Electro Magnet during Electro Magnetic Induction I just read about Electro-Magnetic Induction and few questions came into my mind, which I can not solve by myself. 1. When a coil(Let's say it's a 5 turn coil) connected in a circuit in series, when ... 4 votes 4 answers 1k views ### What is the difference between electrostatic and electric potential? What is the difference between electrostatic and electric potential in a circuit? 0 votes 3 answers 41 views ### Metal/good conductor frame in a changing magnetic field Imagine that we put a metal/good conductor frame into a changing magnetic field. Due to the fact that this is an electromagnetic induction phenomenon, an induced EMF can be measured between the two ... • 25 0 votes 2 answers 58 views ### Why don't we know the electric potential at any point in a circuit, only the difference in the electric potential (voltage)? Why in circuit analysis, don't we know the electric potential at any point in a circuit? 10 votes 2 answers 824 views ### How will the current flow in the figure drawn below? Consider the green material in the figure to be conducting. So, I was wondering how the current will flow in the rod, as the battery is not connected at the ends, but on the surface of the rod. Thus, ... • 450 0 votes 1 answer 25 views ### Relation of potential difference and charge in a capacitor So, there is something regarding capacitors which is bothering me. It is said that in capacitors connected in parallel, the charge is divided between different capacitors, while potential difference ... • 1 2 votes 3 answers 78 views ### Does the direction of coil winding impact the direction of induced voltage? In Case 1) and Case 2) (see the image below) induced current is flowing counterclockwise (from the magnet's POV) if we move the magnet towards the coil (and the circuit is closed, obviously). However ... • 25 0 votes 1 answer 48 views ### Voltage Increase in a Circuit When Holding a Motor Still [closed] My friend and I were trying out a circuit with 6 volts and found that when the motor was spinning slower, the voltage shown on an analog meter was greater. I vaguely guessed that this was caused by ... 2 votes 1 answer 82 views ### Why is it safe to touch a Van Der Graaf Generator? Let's say a typical (50cm radius) Van Der Graaf generator (around 60pF capacitance) is charged to around 200kV (I am following the example seen in this video). According to the formula for an RC ... • 321 1 vote 1 answer 47 views ### What causes the potential difference in a half-cell? This question pertains to the subject of electrochemistry --specifically a half-cell and not a full galvanic cell. From what I understand, a half-cell has a potential of its own. This is voltage is ... 1 vote 3 answers 70 views ### Is there no net voltage over an ideal inductor/coil? No voltage drop? If you have a coil with self inductance: $$\varepsilon= - L \frac{dI}{dt}$$ Then the current is lagging behind the voltage. If you attach a AC source on the coil/inductor and have an AC power source,... • 1,016 0 votes 2 answers 62 views ### Electric Circuits and Kirchhoff's Voltage Law Assume we have a circuit containing a voltage source and two resistors connected in parallel. If I assume one resistor is shorter than the other and they "start at the same height" then ... 0 votes 0 answers 18 views ### How to convert volt-second data into power-frequency domain? guys, I am new to physics. Due to my project, I have to utilize my data in the frequency domain. However, my data is in the time domain. So I wanted to ask how I can transform my Volt-time domain data ... 0 votes 2 answers 53 views ### Current without potential difference, in the given circuit? In the given circuit, the value of current comes out to be 0.5 A Now if I calculate potential difference between point A and B i.e. $$V_B + 3i-1.5=V_A$$ On putting value of$i=0.5A$we get, $$V_A-V_B=... • 388 1 vote 1 answer 42 views ### What causes the electric field in a Daniell Cell? I would like to know what causes the e-field in a Daniell cell. From a chemistry point of view, I do understand that this is initiated by a redox reaction in which Gibbs free energy is decreased. The ... 0 votes 0 answers 10 views ### What happens to electron, when we join two solar panel in parallel When we add two solar panels in parallel then voltage will remain same but current will increase but what exactly happen to the electrons when current increases but voltage remains the same. Also when ... 1 vote 0 answers 26 views ### Why are most solar panel rated at 12 volts or 24 volts? [closed] Most solar panel come in 12 volts or 24 volts, why? 0 votes 3 answers 39 views ### Voltage and electric field in a closed circuit confusion I have a doubt about the intuition behind Electric field and Potential difference. Let's imagine a closed circuit with a battery, a resistance and a lightbulb. We observe that the lightbulb is on. ... • 260 0 votes 2 answers 53 views ### How to understand the model of electric current and potential in circuits? According to what I have learnt, there is always a potential difference across a resistor in a circuit (having a battery). Considering a simple 'resistor' circuit, when we apply an e.m.f in the ... 0 votes 1 answer 50 views ### Energy stored in capacitor over time I know that the maximum energy that can be stored in a capacitor is:$$ U = \frac{Q^2}{2\,C}\,.$$What I am asked is to say how much energy was stored when half of the electric charge that could be ... • 15 0 votes 2 answers 36 views ### If one of the parallels of a parallel combination of resistors is broken, how will it affect the other parallels? All these bulbs have equal resistance and the equivalent current is 6A. I want to know what will happen if bulb 3 is fused. All the sources I have came across say that the bulb 1 and bulb 2 will glow ... • 11 0 votes 2 answers 45 views ### Will a surface perpendicular to the electric field always be equipotential In the figure attached there are four different electric field vectors with different magnitudes, point away from A. My question is will C be an equipotential surface? i.e. will the potential ... 0 votes 1 answer 38 views ### How to find the potential difference between two charged spheres? [closed] Here, the blue sphere (positively charged with$+Q$charge) is at a lower potential and the pink sphere (positively charged with$+Q$charge) is at a higher potential, even though they are equally ... 0 votes 1 answer 40 views ### Current flowing from lower to higher potential In the above circuit, two cells are connected in series to an external resistance$R$. Now the current going from point$A$must return back to point$B$of the cell. But for that it has to pass ... • 585 0 votes 1 answer 44 views ### What does it mean when we say that an object is neutral? I am studying electricity and until about now I never really gave much thought to the statement that equal number of proton and electron means neutral charge. Like if we simplify the question and ... • 757 0 votes 2 answers 58 views ### Voltmeter reading in a bridge circuit Why would it be wrong to calculate the voltmeter reading in the following diagram as one plus 2 ohms is 2/3 ohms as they are in parallel, hence the p.d. reading on the voltmeter must be the current ... 0 votes 1 answer 25 views ### What happens inside a conducting wire if it is placed in an electric field? what happens when you place a long Finite conducting wire in an Electric Field , does current flow through it ? Is Potential Same all over the wire ? i just got these questions in my mind as i was ... 0 votes 3 answers 69 views ### Why Does an Electric Field Arise In This Situation? Suppose you have a battery, and using some wire you connect the positive terminal of the battery to some conductive piece of metal (i.e. an electrode) and similarly you connect the negative terminal ... -1 votes 2 answers 55 views ###$V$-$I$characteristics and circuits [closed] The only solution stuck in my head goes through finding the resistance from the slope of the curves and using it somehow in the solution, however, I can't figure out what voltage do I use for X and Y? ... • 720 0 votes 2 answers 52 views ### Continuity of fields in Electrostatics I have a bunch of doubts in electrostatics. In gauss law div(E)=rho/epsilon, is it implicitly assumed that the partial derivatives exist at every point in space? Is it always true that a collection ... • 13 0 votes 2 answers 50 views ### Confusion about electrical potential difference I am confused why voltage is same across parallel circuit as shown above where wire is an ideal conductor. The voltage at top part of the resistor$R_1$and$R_2$is same.$R_1$has higher resistance ... 0 votes 1 answer 25 views ### Voltage and series circuit [duplicate] Suppose I have 2 series circuit. One will have resistance$R_1$and the other$R_2$. Now my question is why is voltage difference same across both resistor? The top part of both resistors should have ... 0 votes 1 answer 28 views ### If loads are perfectly balanced, and line resistances are zero, is ground wire redundant? Here is my understanding of neutral and ground: The return current through the neutral wire is the vector sum of three phase power. If loads are perfectly balanced, the vector sum is zero, and the ... • 1 0 votes 0 answers 9 views ### Effect of surface contamination on electric field of a charged metal rod I'm trying to understand how the electric field of a charged metal rod gets affect by surface contamination (i.e. dirt, corrosion, rust, etc.). How would the electric field differ between two metal ... 0 votes 0 answers 18 views ### Fluctuative current and voltage graph shown by LabQuest 2 I was in physics class and was tasked to measure current and voltage of a circuit using LabQuest 2. The circuit was connected to a battery, which means it's a DC circuit. But when I use the LabQuest ... • 55 8 votes 10 answers 951 views ### Why is Power = Voltage$\times\$ Current?

So P = I*V because V is the amount of energy per coulomb and I is the amount of electrons going past a cross sectional area in one second. So if we do the math, since V = J/C and I = C/sec, if we ...
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### What's the highest theoretical energy density in a chemical battery?

Is there a theoretical limit to how energy dense chemical batteries can be? How can one calculate them? And what stops us from reaching those limits?
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### Can electric fields of multipoles just be described in terms of monopoles, if so then why do we have to do multipole expansion instead of monopoles?

Can we describe the most complex electric field just using monopoles rather than going into multipoles expansion, because using superposition principle we can tell the potential of entire system?