All Questions
Tagged with electricity voltage
42 questions with no upvoted or accepted answers
5
votes
1
answer
229
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What does the term 'high voltage' really mean?
This might be a dumb question but i am not so familiar with the word voltage:
What does the textbooks really mean when they say high voltage?. Does that mean:
There are more charges so more voltage, ...
- 366
4
votes
3
answers
3k
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How to measure a static electric field?
I looked up google but didn't find any design for measuring electric field that doesn't vary with time.
My own idea is to use two parallel plates (like a capacitor but without the dielectric). In an ...
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2
votes
1
answer
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 ...
- 23
2
votes
0
answers
35
views
Is it possible to overload a thin conductive object with electrons?
A parallel-plate capacitor is a very simple device. To make one, you can take two metal plates, separate them with a dielectric material, and voilà! You have a capacitor.
Given a dielectric ...
- 4,110
2
votes
0
answers
1k
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Minimum Voltage to Sustain an Arc
I've read that after a plasma channel is created in air, the resistance decreases significantly and the arc can be sustained with a much lower voltage, as long as the heat dissipated by the plasma is ...
- 21
1
vote
2
answers
293
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Does a higher voltage always mean a higher electric field strength?
In a step-up transformer, the output voltage is higher than the input voltage, while the output current is lower than the input current. Basically, since P = VI is conserved, the current has to ...
- 337
1
vote
1
answer
663
views
Equivalent EMF of unequal cells connected in parallel
I'm aware of the formula to calculate equivalent EMFs of 2 cells connected in parallel as shown in the top figure. But what happens if we switch the polarity of one of the cells? Shouldn't the ...
- 33
1
vote
2
answers
154
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On a nanoscopic level, what really happens to the electrons in the secondary coil of a step-up transformer?
I know that when AC is passed through the primary coil of a step-up transformer a higher emf is induced in the secondary coil (with more turns) of the transformer. Since energy is conserved, and P = ...
- 337
1
vote
0
answers
102
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Why is the parachutist, in the enclosed image, not electrocuted?
Hello fellow physics experts,
In reference to a recent electrodynamics course a question about electric potential difference was asked. This question states why the dangling parachutist in de picture ...
- 117
1
vote
1
answer
307
views
Is there a potential difference across the bulb after current passed through a diode?
I understand that voltage can exist without current so what I want to ask is will there be a potential difference across the bulb(situated after the diode) when a batteries supplied energy through a ...
- 113
1
vote
1
answer
104
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Confusion about the relationship between current, resistance and potential difference
If the voltage of a component has dropped, what will happen to the resistance? My book says it will decrease but I don't understand the logic. How can current and resistance go down at the same time? ...
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1
vote
0
answers
159
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Electrical resistivity calculation of a cylindrical material
I have a copper rod, its diameter is 13mm, and its height is 13mm. I want to check its electrical resistivity. I have tools to give this copper a constant current by two points (the two black dots in ...
- 111
1
vote
0
answers
191
views
What is steady state current?
I am currently trying to understand the following paper:
On the nonlinear electromagnetic coupling between a coil and an
oscillating magnet
http://iopscience....
- 839
1
vote
1
answer
47
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Voltage of Arcing electricity
In Star Wars, Count Dooku electrocutes both Anakin and Yoda at a distance of about 5m. Obviously this is not meant to be scientifically accurate as it is a fictional movie, but how much voltage would ...
- 11
0
votes
3
answers
126
views
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 ...
- 1
0
votes
1
answer
411
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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 ...
- 220
0
votes
0
answers
36
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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 ...
- 5,831
0
votes
2
answers
55
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Can you please help me understand how Electric Potential and Electric Potential Energy work?
Considering the image we observe the following:
$r_A<r_B \Rightarrow \frac{1}{r_B}<\frac{1}{r_A} \Rightarrow \frac{K(+Q)}{r_B}<\frac{K(+Q)}{r_A}$ (if $0<Q$) and thus
$$\frac{K(+Q)}{r_B}=V(...
0
votes
2
answers
43
views
Can we say that space without electric field is of 0 potential?
Can we say that a given point in space, without any charges nearby, has no electric field, and thus the electric potential in this point is 0?
- 282
0
votes
2
answers
644
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What does a battery produce? Is it Electric Potential Difference (EPD) or Electro Motive Force (EMF)?
I have read a lot of posts about Electro Motive Force, Electric Potential Difference and their differences, but I still confused. What I know is that EMF produces a EPD and keeps it constant, then ...
0
votes
0
answers
26
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Do you get correct graph of transfer characteristic, if you take +ive Vds(constant) value instead of -ive. As mostly CNTFETs are p-chnl FET
I'm studying transfer characteristic curve of CNTFET to get value for mobility, S.S, etc. According to my basic background knowledge, NMOS curves lie in the 1st quadrant. While for PMOS they lie in ...
- 11
0
votes
0
answers
150
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Are the breakdown voltages of silicon dioxide and silicone dioxide the same?
Silicon dioxide has a breakdown voltage of $> 10$ MV/cm [1]. However, I am unable to find any information about the breakdown voltage of silicone dioxide. Since silicone contains oxygen (and ...
- 3
0
votes
1
answer
47
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Does $\frac{V}I = k$ necessarily imply that the wire follows Ohm's Law?
Does $\frac{V}I = k$ necessarily imply that the wire follows Ohm's Law?
https://i.sstatic.net/ClEqP.jpg
Say, for a range of about 15 Volts, I get a good $\frac{V}I = k$ result, after which the ratio ...
- 101
0
votes
1
answer
75
views
How to calculate the voltage of a DC motor?
I have a DC motor. But I don't know its voltage. If I connect with a 3.2V battery, then the motor rotates. Can I find the voltage of the motor from the rpm of the motor?
- 123
0
votes
0
answers
37
views
Is activation voltage the sum of voltage required to collapse depletion layer and band gap energy?
Is the energy released when an electron moves from the valence to conductance band states the activation voltage or is activation voltage the energy required for electrons to overcome the depletion ...
- 31
0
votes
0
answers
32
views
Insertion of an electric component in a resistance connected to AC supply
Kindly ignore the written matter... I don't understand, how the current would remain the same even after a capacitor is introduced in the circuit...
This is what I did:
The current after insertion ...
- 39
0
votes
2
answers
86
views
Electrical vs Heating Insulation
Let's say we have a 120V cable and a 600V cable, this means that the 600V needs more electrical insulation to prevent the insulator from exceeding its dielectric strength. But in the other case, the ...
user215726
0
votes
0
answers
234
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How powerful of an electric current would I need to fully ionize plasma under the specific circumstances below?
in a cylinder shaped vacuum chamber 4 inches in height and 5 in diameter at 1/100th atmosphere, with 3 cathodes at the face arranged in a equilateral triangle in exactly between the center and and the ...
- 393
0
votes
1
answer
105
views
How do I keep the peak voltage in a coil connected to a signal generator constant, given that I'm changing the frequency?
I want to vary the frequency of the A.C supply, and hence change the peak current in the circuit. But V=IR, so won't the peak voltage also be changed if I change the peak current?
- 254
0
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0
answers
53
views
What happens if an electrical current has two paths of unequal length?
Suppose I connect one 1 km cable and one 1000 km cable to the same pole of a power source and also connect them together at the other end. Suppose (theoretically) the longer cable has the exact same ...
- 101
0
votes
0
answers
49
views
Transformer vs Inductor for lighting a bulb or any other appliance
There was a question in my school physics exam which is as follows:
Consider a 100W bulb which operates at 50V dc. John wants to light this bulb by a 200V ac source. What component should he use, ...
- 288
0
votes
0
answers
131
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Is it possible to raise the voltage of a power source by lowering its current indefinitely (i.e. transformers)?
Let's say you have a D battery. You wire it up to the primary of a step-up transformer, which you then in turn wire up to another step-up transformer,...etc. Is there a limit to how high the voltage ...
- 1,968
0
votes
2
answers
39
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Determine the size of a conductive medium
Are there any measurable characteristics that would allow one to discern the size of a conductive medium?
Say I apply the same voltage to a two foot long wire and a four foot long wire. Is there ...
- 11
0
votes
3
answers
144
views
How does the initial turn-on transient decay into the steady state in a given circuit?
How does the initial turn-on transient decay into the steady state in a given circuit? For example, in a parallel circuit, how does the voltage over both arms of the parallel circuit equal to that of ...
- 1,235
0
votes
1
answer
810
views
Why does no current flow in a smartphone charger when it's plugged into a socket, but no phone is connected?
According to the fact that a phone charger consists of a transfomer and a recitifier, there should - still - be a difference in potentials, even though no phone is attached to the charger.
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0
votes
3
answers
139
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Can voltage be measured manually?
I am a novice in the subject of electricity so please bear with me if my questions seem naive. What I basically wanted to know is that what is voltage in its essence and whether it can be measured ...
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-1
votes
2
answers
36
views
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 ...
-1
votes
1
answer
220
views
How same power is distributed in different voltages in power lines?
I have seen when a resistor is connected to a battery, it carries the same voltage across the resistor, if the resistance is changed the current changes but voltage remains the same making the battery ...
- 356
-1
votes
1
answer
144
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The flow of electric current
If positive charges have higher electric potential difference than negative charges then why the negative charges (electrons) are the one that are moving in a circuit? and to my knowledge the ...
- 1
-1
votes
1
answer
411
views
Not enough current to supply load
Are there cases where a power supply can offer xV, which is required by a device, but be unable to supply enough current?
For example, a voltage divider not only lowers voltage, but limits the ...
- 119
-1
votes
1
answer
612
views
Measured voltage on coil
I have a simple circuit of coil with inductance L $$u_c(t)= -L\frac{di}{dt}$$ and AC source with output voltage $u_s$
What is actually measured by the voltmeter ($u_c$, $u_s$ or $u_s - u_c$)?
If ...
- 123
-2
votes
2
answers
40
views
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 ...
- 47