All Questions
Tagged with electricity voltage
396 questions
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What is resistance precisely?
Is there a mathematical definition for resistance because I cannot find any. On the internet I find definitions such as:
The electrical resistance of an object is a measure of its opposition to the ...
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0
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16
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Speed of current at higher and lower potential [closed]
It is said that, charge has more potential energy at higher potential as compared to lower potential in an electric circuit. So, is the speed of current faster at higher potential and slower at lower ...
2
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3
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95
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How do circuits work at a subatomic level?
I imagine it’s like this. Let’s say we connect a copper wire to a battery’s terminals. The electrons from the negative side will thus exert a push on the electrons near the wire and it will continue. ...
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3
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71
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Can you loop a charge pump?
Is it possible, to charge two capacitors in parallel(eg. each two volts). Discharge them in series to a third capacitor(4 volts). Charge the first capacitor again with the initial voltage(2 volts). ...
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Understand power rating in layman terms
I have recently started the chapter of electricity of class 8. I am not understanding the concept of power rating of appliances. When we say that a bulb is rated 220V-100W, which means, according to ...
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How do I compute the voltage accross a cell membrane given microstate of neuron (distribution of charged ions)?
I am not a physicist, and I'm not sure what keywords to use to search for this.
I'm trying to understand how I could in theory quantitatively know, what the voltage across a cell membrane in a Neuron ...
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2
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140
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What is the "closed circuit" of a bug swatter racket?
There are bug swatter racket that can kill fruit flies, mosquitos, or flies, if the insect touches the metal mesh.
However, when I look at the construction of the device, the metal mesh is all one ...
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377
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Why doesn't voltage increase when the wire length increases; there's more work to be done?
This Q&A did not answer my question.
The voltage of a circuit is the difference in each Coulombs potential energy at the negative pole, compared to the positive pole. At the negative pole, there's ...
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Ideal Superconductor connected to Zero Voltage
If an ideal superconductor was just left alone, with no potential difference, what would be the current flowing in it?
According to Ohm's Law, $V = IR$
Hence, if a superconductor of $0\Omega$ ...
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2
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190
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How do you measure AC voltage of your mains domestic electricsupply?
If I have a DC voltage source, I can connect a voltmeter across it and get the voltage value. But how do I find out the AC voltage of a voltage source? What will happen if I connect a voltmeter across ...
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If a downed powerline contacts the metal chassis of my car, can I touch any metal parts of my car while sitting inside of it?
consider the following situation. I parked my car underneath some high-voltage lines – let’s say 380 kV-lines. Suddenly, one of the lines breaks in the middle due to a storm and one end of the (still ...
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Piece of iron instead of a proper fuse
In a video game Dying Light 2, there are those electrical boxes that you open and then "fix" by putting a piece of iron (I suppose). Assuming voltage $U$ is being produced and is supplied ...
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3
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308
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Electric shock: positive vs negative voltage
A high voltage wire can either have an large excess of electrons (net negative charge density), or a large defect of electrons (net positive charge density).
The voltage difference between the wire ...
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3
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99
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How do we correctly handle a power source and a capacitor in parallel?
$\newcommand{\d}{\mathrm{d}}$
Here $V$ is an alternating supply, $R$ is a fixed resistor and $C$ is an capacitor. All components, including the diode, are ideal. Say $V(t)=V_\max\sin\omega t$ - with ...
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Why do we call high terminal the positive side?
I want to confirm if I understand something correctly.
We call the "high potential terminal" the positive side (cathode).
Though, electrons move from negative to positive. Logically, ...
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If a person hanging on a live wire of 440 V in air with no contact with ground, will he get a shock why or why not? [closed]
my sir told me that he will get a shock, but why not bird then
he replied bird has legs acting as insulators
i am in confusion what is the right explanation to this
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Explanation of Potential Difference
My question is to verify if my thought process below is correct.
So in a circuit the charge will flow (the current). When the charge flows there is resistance which is the collisions of the charge ...
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139
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What if we used massive voltages to create a Lichtenberg figure in acrylic?
https://en.wikipedia.org/wiki/Lichtenberg_figure
I cannot find anywhere online what the result would be if I used, for example, 1GeV compared to the 10-20MeV which are usually used. This is all ...
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3
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121
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Why won't the bulb light? [closed]
Here's what the marking scheme says: "Capacitor gets charged first and acts as an insulator/blocks current".
However, electrons flow from negative to positive, so shouldn't the electrons ...
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3
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126
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Potential drop against internal resistance of cells in combination
Suppose two cells of emf and internal resistance e1, r1 and e2, r2 respectively are connected in series. The negative electrode of 1st cell is connected to negative electrode of the second cell. Why ...
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410
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How does a large resistor in parallel with a thermistor affect the voltage-temperature graph curve?
I want to know whether my understanding of the thermistor being in parallel with a large fixed resistor is correct. There is another resistor in parallel with the thermistor but that is fixed and not ...
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3
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65
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Why is a powersource characterized by voltage?
Why is it that powersources are characterized by their voltage? If we are given a power source with a certain voltage we know that the potential difference per charge will be constant, and it will be ...
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3k
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How does Neutral Wire has lower potential than Live Wire?
This is my current(and most probably very incorrect) picture of how electricity comes in my house.
What I think of this picture is that, the transformer produces current in my house circuit (by ...
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Does current make the full return trip?
In an AC system, the neutral wire is said to provide a return path for the current back to it's source. Given that the current is said to be alternating back and forth, how does this work, does the ...
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For a charge to have potential, why bring test positive charge closer to the point charge from infinity in uniform speed? why not variable speed?
For a charge to have potential, why bring test positive charge closer to the point charge from infinity by keeping it in 'electrostatic equilibrium'? or bring the charge closer to the point charge ...
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When using a screwdriver tester i am completing the circuit with 110v?
if i use a screwdriver tester, i am part of the circuit with 110v passing my body? isn't this dangerous?
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"Why do power lines use high voltage?" Loss in power equal to Current*Voltage? [duplicate]
I define P is the average power. So $P=IV$ and $I=\frac{P}{V}$.
$P_{loss}$ I define to be the power loss, which is equal to $I^2R$.
Substituting for $I$, $P_{loss} = \frac {P^2R}{V^2}$
So I get that ...
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93
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Why can we talk of electric potential under AC?
An electric potential $V$ is defined by the relation $E = - \nabla{V}$. The existence of such a potential is true in electrostatic (constant electro-magnetic field) because of the Maxwell-Faraday ...
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234
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Why can't I observe a voltage between two capacitor plates when only one of the plates is connected to a battery?
Let's say I have a battery and a capacitor that is neutral. Now I connect the battery positive terminal to only one plate of the capacitor. From what I know, there is a potential difference between ...
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1k
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Create static electricity from batteries
I have to demonstrate a simple DIY electroscope.
For this I need to create a source of static electricity using household materials. The weather at my place is very humid. So all my efforts of ...
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194
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What is the maximum voltage gradient between two electrodes? [closed]
What is the maximum voltage gradient between two electrodes?
It would be great if you put the reference to your answer.
UPDATE
Our environment is vacuum.
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2
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Voltage between 2 points of net electropositivity
Ok, so suppose we have 2 points that are overall electropositive but one is "less positive" than the other. Say point A is +50 V and point B is +20V. How will we calculate the potential ...
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3
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423
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What exactly is electric potential? [duplicate]
My book says:
When a small positive test charge is placed in the electric field due to another charge, it experiences a force. So work has to be done on the positive test charge to move it against ...
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Potential divider problem [closed]
What does the curved arrow represent? The answer states that L1 will be dimmer than L2.
From my current knowledge, moving the contact K closer to X will somehow increase the voltage of L2 meaning it ...
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4k
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Why is it easier to raise AC current to high voltage than DC?
In my country (and maybe all around the world I don't know) once electricity has been generated, it is then raised to 200k Volts for transportation.
I know this is to reduce the loss. Given $P=U.I$ ...
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357
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Voltmeter connected to parallel circuit
This is my current understanding. Voltage is defined to be the potential difference between 2 points, hence it only makes sense for a voltmeter to be connected in parallel. But why must this voltmeter ...
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3
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Brightness of bulbs in Parallel
When adding bulbs in parallel, the brightness is brighter than that of series. But does that mean adding bulbs in parallel will increase the brightness of the other bulbs?
My intuition is as follows: ...
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1
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124
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Transformers in Power transmission [duplicate]
Recently I learnt that transformers are used in the national grid to increase the voltage, so we get less current. But my understanding V=IR and by increasing the voltage we get more current, so what ...
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3
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1k
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How does current actually flow in a wire?
When I was in my school I was taught that the electric field due to the battery is along the wire (from $A \rightarrow B \rightarrow C \rightarrow D $) and these are responsible for electrons at each ...
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Which electrons kill you during electrocution?
I understand that there are three velocities in play in a circuit (I haven't studied Physics past high school so give me some rope)
v1: the velocity by which the electrical field propagates through ...
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4
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1k
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What is the difference between electrostatic and electric potential?
What is the difference between electrostatic and electric potential in a circuit?
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2
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73
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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?
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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 ...
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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 ...
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Is it actually possible to make an amputated hand move with electricity? [closed]
I was watching a TV show that involved the police tracking down an insane person who was using deceased limbs to perform experiments on. It then cuts to a scene where they find the safehouse with what ...
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1
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High voltage in transmission line [closed]
I'm trying to understand why high voltage is used in transmission but I seem really confused by the explanations I read.
Here's what I could make out:
$$P_\text{loss} = \dfrac{ΔV^2}{R_t} = \dfrac{(...
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What is the field emission current at very high voltages?
Consider two planar metal electrodes at low temperature, separated by vacuum, at a given voltage (in conditions that allow electron emission from one electrode to the other).
For large voltages, the ...
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Does an open circuit have electrons accumulate in it?
This is what I have imagined electricity to be like, where the blue balls represent the free valence electrons in a conductor atom, and the electrons flow towards the positive electrode as the ...
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How do we know that a battery has 5 voltage?
Since Voltage = work done per coulomb and in a battery we don't know how much coulomb exists (or is it known because I read somewhere that we are unaware) and for the work done I assume we can find it ...
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What is the electric potential of each of the 2 points of an alternating current source?
I have that question.
I am not asking about the voltage or electric potential difference.
I guess the answer will depend on what type of generator is used in the power plant: maybe synchronous. Can ...
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