The study of the presence and flow of electric charge. Charges, currents, fields, potentials.

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2answers
91 views

If a perfect conductor were to move, what happens to the electrons?

Theoretically, if a perfect conductor were to move (or start spinning), would the electrons inside it remain where they were or be 'dragged' along with the conductor?
4
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3answers
4k views

Using Electrostatic Force to Repel Dust From an Object [closed]

I have two 4,000V, 2.5mA, DC power supplies and am attempting to use them in such a way to cause a 6x4x1-inch ABS plastic object to repel dust from the ambient air and prevent this dust from settling ...
0
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0answers
18 views

How do I evaluate this general magnetic dipole equation for this given setup?

This shouldn't be too hard a question (mostly focused on vector multiplication) but I'm still not confident in my answer. Basically, I am looking at the force between two magnetic dipoles and using ...
0
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1answer
25 views

Electricity parallel combination

Why is resistance lower in a parallel configuration and therefore current is more? Shouldn't resistance be addition of all resistor's resistance?
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2answers
132 views

What will happen when lightning strikes on the surface of the deep sea?

The lightning is having enormous amount of energy, as it strikes the ground it makes various electrical and magnetic effects. If the lightning strikes a tree, that will be burst by lightning. ...
0
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2answers
58 views

How long do electrons take to “decide” how to go through a circuit?

Many other people have asked how an electron decides which path to take, but no one has asked how long do they take. Is there an equation for their "uncertainty" time? Do they decide instantaneously ...
1
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0answers
15 views

Is their a visual difference between air-gap sparks of the same voltage but different current?

For example, if this spark gap has a kilovolt of power behind it @ 1A and the other is also at a kilovolt but is @2A will there be a visual difference (i.e. will the one with higher current be ...
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0answers
22 views

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 ...
0
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3answers
45 views

The standard definition of current

The book says current is the rate of flow of charge per unit time, but I don't understand whether it is rate of flow of charge through a single cross-sectional area per unit time or the entire amount ...
1
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1answer
50 views

Why charge distribution is greatest at pointy edges of a surface? [duplicate]

If we have a conductor which is in electrostatic equilibrium, then the charge distribution over this surface $\sigma$ is greatest at the sharp edges of that surface. Why is this the case? I want ...
5
votes
1answer
493 views

Why does the electron volt seem inconsistent with mass?

If I understand correctly, an electron volt is the work done when an electron is moved from a plate with a voltage of 0V to another plate with a voltage of +1V. This is represented by $V = W/Q$, or $W ...
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0answers
21 views

How can I have a voltage in hall effect with zero magnetic field?

How can we obtain a voltage with no magnetic field is applied to the semiconductor? They told me that if the points where I measure the potential difference are not at the same level I would obtain a ...
0
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1answer
28 views

What is the purpose of defining an electric field, and how to apply it?

So, I've been reading an introductory book to physics. I've gotten to the point where I understand Coulomb's law, and now the book is introducing electric fields. I'm having a hard time ...
1
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3answers
74 views

How can Ac be listed as a single voltage

How can AC be listed as a single voltage (e.g 240V AC) when it constantly varies and what does this have to do with RMS Voltage.
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2answers
67 views

How do you calculate maximum current density for alternating currents?

I think the answer is neither here nor on Wikipedia but forgive me if it is, I don't read maths well. This question applies specifically to current density during transcranial stimulation with either ...
0
votes
0answers
64 views

What is the cause of the time-varying electric and magnetic near-fields around a wire with a 60Hz AC current?

I know that it's the accelerating electrons in an AC current that are the cause of far field effects. But, what about the reactive near field close to a wire that has a 60Hz AC current? What is the ...
1
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1answer
26 views

Conductivity of electrically ionized water

So we see people putting salt in water for increased conductivity. What if you ionize the water with voltage. Positive and negative splitting. One side will have more free electrons than the other ...
0
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1answer
74 views

An infinite value for an electric field?

Consider a system of point charges. To calculate the value of an electric field at a point, we consider the contribution of the electric field from all the charges at that point. Consider the ...
0
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2answers
218 views

Is it possible to generate an instrument which can generate wireless electricity?

Is it possible to build an instrument which can generate wireless electricity? I ask this since at present the electricity was passes through wires and i thought about wireless electricity I am ...
1
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1answer
36 views

Why does corona discharge generate ozone?

When a corona discharge occurs for instance in a laser printer, ozone is generated. What is the mechanism that produce ozone for high voltage discharge?
26
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2answers
2k views

Static electricity and door handles

I have a pair of shoes, which seem to isolate me from the ground. In effect I'm gathering static charge and every time i grab an aluminum door handle, that current discharges and that hurts. Ouch. I ...
4
votes
3answers
9k views

How can you have a negative voltage?

How can you have a negative voltage? I don't really understand the concept of negative voltage, how can it exist?
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2answers
402 views

What actually happens at the microscopic level in a Zener diode in reverse bias?

A Zener diode is used as a voltage stabilizer. The graph of current vs voltage of Zener diode clearly shows that there is a constant voltage across Zener after the breakdown voltage as the current ...
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2answers
271 views

Derivation of Faraday's law using Lorentz force?

For a stationary loop of wire with a time varying magnetic field $\vec{B}(t)$ through it. Is it possible to derive Faraday's law, using only the Lorentz force $$\vec{F}=q \vec v\times \vec B \tag ...
5
votes
4answers
10k views

Is it possible to flow current in open circuit?

As I know a battery is an example of a closed circuit where it can then produce electricity , electrons will flow from negative pole to positive. A chemistry representation of this battery is for ...
1
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1answer
126 views

Wait… why exactly does farady's ice pail experiment prove Gauss's law?

You'll notice there are no equations in this: that's because this is a question of morale, not of math. But a humble one at that! I come to learn, not to expound. But don't let that limit the form ...
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4answers
436 views

Which of the following has higher resistance - milliammeter or ammeter?

The question is the same as the heading - Which of the following has higher resistance - milliammeter or ammeter ? Now my teacher's and my answers don't match. It is assumed that the spring constant ...
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0answers
25 views

Earth connection through resonant inductive coupling with Schumann resonances possible?

I have been playing around with Tesla coils for a while now, but one limiting factor for portability is the fact that it requires an earth connection on the secondary coil. Since a Tesla coil works ...
0
votes
1answer
67 views

Basic concepts on Electricity [closed]

How do electrons move? I mean really do they move? I read that they move in circular shells AROUND THE NUCLEUS. How can they move in the conductor? I have read that there are valent electrons that ...
6
votes
2answers
684 views

How exactly does a solar flare cause a power line surge?

There are occasional large scale electrical blackouts caused by solar flares. Quebec Solar Flare Blackout My question is: what affects the severity of the problem? It obviously depends on the ...
2
votes
5answers
2k views

Why don't positive charges move?

Charge is carried by electrons moving. The protons are always stationary. The answer I found online is the protons are stuck in the nucleus so they can't move ("strong nuclear force"). But why can't ...
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2answers
41 views

Quality Factor in a Parallel LC Circuit

I was wondering if there is a notion of a quality factor in a parallel LC circuit, since there is no resistance. One can show that this circuit has a resonance frequency as follows: Impedance: ...
43
votes
3answers
6k views

Why do electric sparks appear blue/purple?

Electric sparks tend to appear blue or purple or white in color. Why?
2
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4answers
15k views

domestic electric AC wiring - Live and Neutral correct or not? [closed]

On electric circuits, with $120$ or $230$ AC mains, there are the wires Live and Neutral. The wiring isn't symmetrical : following the circuit, you cannot switch $L$ and $N$. However, in Italy, ...
4
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1answer
467 views

What determines how much electrical charge an object can hold?

What determines how much electrical charge an object can hold? Does increase voltage force more electrical charge to be store in an object (Van de Graaff generator), since electric field increase as ...
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1answer
80 views

What actually happens when electrons 'collide' with other electrons in a conductor to produce heat in an electrical circuit?

Textbooks describe resistance as involving electrons colliding with other ions in metals, resulting in a heating effect, though how exactly is this achieved? Although I am not required to learn the ...
2
votes
2answers
162 views

Does “ac current” mean that the electricity goes left and right or just changes polarity?

AC goes one way in one phase and the opposite way in the other phase, but is going right and to left, or is it only changing the polarity from (-) to (+)? If light bulbs turn off and on (so fast we ...
4
votes
4answers
1k views

How can there be a current and an electric field in an idealized wire with no voltage drop?

In an ideal circuit, How can there be a current b/w points a & b, when there is no potential difference and thus no electric field between a & b? If there is no current, then where does ...
0
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2answers
39 views

Why can insulators be charged by friction but not by conduction?

When you charge an insulator by friction, the close contact of two electron clouds (each from a different medium) allows for electrons to be transferred between them. Yet why can the same not be ...
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vote
1answer
61 views

Understanding electric field and potential inside an half-connected wire

Let's say we have a 9 V battery and a wire as shown in the image below: Let's assume H is the reference for measuring potential. I know the potential in F is 9 V, and I know the electric field in F ...
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3answers
61 views

What does it mean when we say that power of a bulb is 10 W? Since $V/I=$ resistance is a constant, how can power $=VI$ be a constant?

My question is simple. In Ideal situation, at constant temperature, we know that normal appliances like a filament bulb has straight Voltage vs Current graph, meaning its resistance is constant or ...
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2answers
60 views

Potential difference inside charge distributions

Always when I think about potential difference inside a symmetrical charge distribution, I think of it being equal to zero because it's dependent on the field and I imagine the directions of each of ...
1
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1answer
43 views

Why did the electric potential energy fall in this situation?

Suppose you have two capacitors configured as shown in the image below. One of them has charge $q$ and the other one is uncharged. Then, you close the switch, allowing charges to flow. After ...
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vote
2answers
66 views

Electric field on the surface of a charged sphere

We know that the electric field for a point charge is $$ E = \frac{KQ}{R^2}. $$ If $R$, i.e. distance from the electric field producer to the point where we want to find the electric field becomes ...
-1
votes
2answers
45 views

How can we prove that electric field originate from and terminate on charge using Gauss Law?

We already know that electric field originate and terminate on charge only and they doesn't make any closed path. But is it possible to prove this statement using Gauss Law ? If yes then how ?
11
votes
3answers
969 views

Why do lightning rods have a sharp point at the top?

We know that a lightning rod or lightning conductor is a metal rod or metallic object mounted on top of an elevated structure and, if we look closely, most of them have a sharp point at the top. What ...
1
vote
1answer
29 views

single conducting plane and parallel conducting plane with opposite charge all have different Electric field but same Electric Flux?

Considering the electric field $\vec{E}$ created by an infinite conducting plane $M_1$ having surface charge density $\rho_s$ locate at xy plane at $z = 0$ with $\hat{a}_z$ as unit vector ...
0
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0answers
21 views

Do free charges in conductor in electrostatic field still moving even after the internal electric field is zero?

By the boundary condition, if an external electric field is apply to a conductor. The free charges of the conductor will move so that in the end There is no electric field or charge inside ...