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

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Is this a good explanation of electron mobility to the layman?

I'm writing an informative paper on graphene for my writing class (layman-oriented), and was describing electron mobility in very simplified terms. Let me know if anything is mistaken, badly ...
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1answer
25 views

How are charges formed in clouds during lightning?

How are charges formed in clouds that are responsible for lightning?
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1answer
13 views

The working of rheostat/ potentiometer [on hold]

I can't grasp the concept of how a rheostat divides potential and acts as a variable resistance in a circuit.I have tried asking my teachers and fellows but their explanation hasn't been satisfactory. ...
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2answers
46 views

Why is voltage essential in circuits?

I understand what voltage is, but why is it necessary for an electric circuit to function? Why can't current flow without a voltage?
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0answers
55 views

Is electricty matter? [closed]

Electricity is a flow of electrons. I'm right until here, and matter is something that takes up space. (I can't be in the same place as my friend does). And correct me if I'm wrong but an electron ...
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1answer
139 views

How can a material conduct heat but not electricity

Mica is a good conductor of heat but an electrical insulator. According to free electron theory (which applies only to metals) free electrons carry heat and electricity. Therefore, thermal ...
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1answer
63 views

Electric Motors: why do they draw more current when stalled, and less when moving? [duplicate]

I'm familiar with how an electric motor works, and also familiar with what stall current and free current refers to in an electric motor. I'm also somehow familiar with the notions of energy being ...
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1answer
62 views

Why do high voltage transmission line workers need a Faraday cage suit?

In this video the high voltage transmission line workers are wearing a Faraday cage suit. Why is this needed? Without the Faraday cage, the resistance of the human would be very high compared to the ...
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0answers
48 views

Resistance of a metal sphere

How would you go about calculating the electrical resistance of a sphere when you only know it's radius and conductivity? I know with cables you can use $$ R = L/(g \cdot S),$$ but I don't know how ...
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2answers
27 views

Relation between power & thickness of the filament

Tell me what relationship is used to solve the question given below. There are three bulbs of power 60, 100 and 20; which one has thickest filament for same source? (a) 100 (b) 20 (c) 60 ...
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0answers
10 views

Electrode (de)conditioning for breakdown

The breakdown voltage between two electrodes in vacuum depends on their surface condition. If you increase the voltage across the electrodes smoothly, at some voltage $V_0$ you will see the first ...
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2answers
39 views

potential difference across a bulb

I am doing some self studying over the summer for fun and I'm working from a book that does not provide answers. I came across the following question, and I will present my solution. I was hoping ...
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1answer
28 views

When potential difference is equal to the emf, isn't the current 0?

I have been told that the $emf$ is equal to the potential difference across the terminals of a cell when no current is flowing. Does that mean that the current is zero ($I=0$)?
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5answers
764 views

What causes contact resistance?

When two components are combined in an electric circuit, there is apart from their own resistances a contact resistance at their junction. This causes a sudden voltage drop of ...
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1answer
51 views

Why isn't this calculation of the energy of a light wave correct? [closed]

I'm trying to calculate the energy $J(T)$ that monochromatic light wave with electric field strength $E(T)$ supplies to unit electric charge over period of time $T$: $J(T)=\int\limits ...
3
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1answer
58 views

How are analog clocks synchronized? clocks on the frequency (50 Hz or 60 Hz) connected with power cable to the electricity network

Those clocks that use a motor that runs exactly on the frequency (50 Hz or 60 Hz) and connected with power cable to the electricity network. I mean - a frequency controlled clock / alarm - the ...
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1answer
65 views

Can lightning actually weld fillings in your teeth?

So, I remember sometime in my childhood, someone was teaching me about lightning safety, and they explained that it was important to crouch low but keep as little contact with the ground as possible, ...
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0answers
24 views

Three phase permanent magnet generator question

For my three phase permanent magnet generator, my coil plate is going to remain stationary to avoid having to use a commutator. Instead my magnetic plate will rotate. If instead of having just one ...
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0answers
23 views

Can an open cup attenuate radio waves as well as a Faraday cage?

The problem is that thieves in my neighborhood are using a power amplifier to increase the "bubble distance" of my car so that it thinks that my key fob, which is sitting in my house, is next to the ...
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2answers
61 views

Magnet dimensions for 3-phase permanent generator

I'm making a 3-phase permenant generator. According to Faraday's law, the emf produced is negative number of turns times the change in magnetic flux over the change in time. If it is only the CHANGE ...
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1answer
30 views

How do domestic appliances work at different voltages when the applied voltage is same for every appliance?

Generally, the electric connections at home are in parallel combination. How is it possible for a geyser(220 Volts) and a cellphone charger (5 volts) to operate at different voltages in a parallel ...
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1answer
67 views

Can electrons reflect light?

Lately, I have been watching sparks while connecting my electronic devices and I can notice that electricity is kind of blue, and theoretically it's blue because it reflects blue wavelengths?? And ...
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1answer
26 views

Current - Voltage curve for non-ohmic material

Forgive me for I am a math student and am quite ignorant in these topics. I would like to know, at least implicitly, how the current intensity of a lightbulb, for example, relates to the potential ...
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1answer
20 views

DIY Ring Light: Grounding Bulbs in Circuit

I'm looking at making a DIY ring light using multiple fluorescent light bulbs. I'm in New Zealand and we get 230-240V and an current of 10A. I know from this I could rig up to 24 100W bulbs in series ...
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1answer
38 views

What is the frequency of each of the moving electrons in a DC current?

I know that the DC current has 0 frequency. But what about each individual moving electron that makes up that DC current? Of course there has to be a frequency as all moving electrons are vibrating at ...
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0answers
24 views

Do electrons move easier depending on the way a TIG tungsten head is grinded?

I'm in a TIG welding course, and during the course we (inevitably) messed up a few (suicidal) tungsten heads by grazing/suicide dive into the molten puddle during operation. Standard procedure is to ...
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1answer
27 views

Electricity on magnetic powder

I had the idea of, what if you ground up some magnets into a fine powder, what would happen with the powered, and how would it act? After some google searches, it seems that this isn't done very ...
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2answers
33 views

Why the electric potential energy the charges carry in a electric circuit does not vary with its distance to the opposite terminal?

I understand that with wires assumed to be ideal, there is no resistance and subsequently no force acting on electrons, hence no work done and p.d. across any segment of wire. However, as the ...
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2answers
54 views

What happens with the electricity in a disconnected wire?

I just want my theory confirmed/corrected. Lets say I have a long wire, which gets disconnected from both ends at the same time, where does the electricity go? My theory is that it goes back and ...
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1answer
48 views

Is it dangerous to use the water tap/bathe/shower during a thunderstorm?

As the title says, is there any danger in touching the water tap or sitting in a bath tub etc. inside the house during a thunderstorm? I heard that it is dangerous, as the lightning could hit some ...
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0answers
16 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 ...
3
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2answers
89 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?
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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
57 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 ...
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2answers
119 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. ...
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0answers
12 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
21 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 ...
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3answers
38 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 ...
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1answer
45 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 ...
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0answers
17 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 ...
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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 ...
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1answer
492 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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3answers
72 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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0answers
59 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 ...
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1answer
21 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 ...
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1answer
70 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 ...
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1answer
29 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?
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2answers
43 views

Capacitance of a single charged plate?

Lets say we have a single plate that has a charge of +Q on it. A plate with charge -Q is infinite distance away. Will the plate with +Q have a capacitance associated with it? Why or why not? I was ...
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1answer
63 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 ...
2
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2answers
59 views

Why is the electric field highest in regions of highest resistance?

I know Kirchhoff's law and that current must be constant. But what exactly is the phenomenon, from first principles, that causes the electric field to be stronger in a region with lower carrier ...