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

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Transient process of turning on electric circuit, initial EM pulse propagation

Suppose, there are 1) a DC power source, 2) a switch, 3) a resistor 4) two wires of relatively low resistance (in comparison with the resistor) connecting the source and the resistor. Before ...
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3answers
102 views

How feasible is it to power your home with a bicycle? [on hold]

This article claims "60 Minutes On This Bicycle Can Power Your Home For 24 Hours!" How feasible is this claim? Sounds great - but the skeptic in me says "yeah, right." Hope this is an acceptable ...
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1answer
80 views

Charge of electron in AC/DC circuit

If electrons in a DC circuit going through a metal wire carry only negative charge from negative to positive, then in a AC circuit through a wire does a electron carry both a negative charge and ...
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20 views

What happens to metal when exposed to an electric current for an extended period of time?

I was wondering what happens to the actual metal (copper, aluminum, silver, gold) when electricity is ran through it for a long period of time. Say years like the wire in a house. Does the ...
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1answer
39 views

Bulbs glow with different brightness in one arrangement and the same brightness in the other arrangement

The question is: Mr.X decorated his house with fairy lights on a celebration.He bought 40 bulbs and operated at 220V. He found all the bulbs are glowing with different brightness. He called his friend ...
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23 views

Charging Copper ball bearing

I want to conduct an experiment to observe the trajectory of charged particles in applied magnetic and electric field. Thus, I want to charge a copper bead/ball bearing. How can I electrically charge ...
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19 views

How do I calculate the effective resistance in this circuit? [closed]

How do I calculate the equivalent resistance across A and B when i) All resistors have a resistance in the given circuit of $~\mathrm{R }$? ii) The resistors in the given circuit have values as ...
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16 views

Tesla's radiant energy system [closed]

Would Tesla's radiant energy system work better on earth if there was no magnetosphere, and more radiant energy from the sun is able to reach the system? Thanks!
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1answer
21 views

Potential Difference

Ohm's law: $$V=IR$$ Here $I$ is the current in the circuit, which is equal to charge flowing per unit time. $R$ is the resistance offered. $V$ is potential difference. What's the physical ...
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1answer
34 views

Current carrying conductor

In a current carrying conductor, the net flow of charge is zero. Is this possible? Arent the charges moving? Are the charges moving in a current carrying conductor?
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2answers
55 views

Possiblity for particle to be carried by a wave such as a photon or electromagnetic wave/waves in general for means of transportation/travel? [closed]

I am wondering whether it is possible for a photon/EM wave to carry a very small particle like an elementary particle or smaller on it like a highway carries a car traveling on the highway or an ocean ...
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2answers
36 views

Trouble understanding Electric flux and gauss law

Well, i know that the electric flux is the number of field lines passing a certain area, but (1)what does that mean? I can't the concept itself. I know it have many applications, gauss law one of them,...
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33 views

Electron Beam does not appear to be continous (CRT Experiment)

https://www.youtube.com/watch?v=2xKZRpAsWL8 Why do you see patches of purple in the tube? Shouldn't there be continous lines of colour? As far as I know, you see the rays because some of the ...
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0answers
25 views

Why does static charge build up and how do I prevent it?

I bought my 11-month-old son a tricycle from Smart Trike (official website) and I have noticed that after a few laps indoors on my marble floors static charge would build up in him as I can see his ...
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1answer
35 views

Is a straight lightning bolt possible?

Recently, I saw a demonstration where an annealed steel rod and a hardened steel rod were made to fail from tensile stress (they were pulled on like an elastic band and snapped in a vice-like machine) ...
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1answer
41 views

What is the maximum amount of electricity I can draw in 48 hours from a domestic supply? [closed]

An electricity company is offering free electricity for a 48 hour period every week. The rate the rest of the time is very expensive. How much power can be drawn from a domestic UK supply? Would it ...
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1answer
35 views

What is the average range of voltage of lightning in sky?

I wondered how much energy is required to produce , such a loud sound? What is the average range of voltage in sky? Is there any possible way to store it ,and use when needed?
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2answers
64 views

Electrical equivalent of inverted pendulum

Background I am working on a summer project to design labs for undergraduate students. One of the topics is feedback and there is already quite a lot of stuff about passive feedback, so we might add ...
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1answer
31 views

Energy dissipation in current flow

In section 4.8, Energy dissipation in current flow, of Purcell and Morin's Electricity in Magnetism, the expression for the power expended by a resistor is derived. The sections includes the following ...
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3answers
797 views

Is there an electric field around neutral atoms?

Even if the atom is neutral (equal numbers of protons and electrons), the electrons and nucleus form an electrical dipole, so there is still an electric field around them, even though the total charge ...
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1answer
44 views

Why Electric current is considered fundamental quantity [duplicate]

It seems to me electric charge is more fundamental than electric current. Can anybody explain why electric current is taken as fundamental quantity and not electric charge?
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0answers
22 views

How pseudocapacitors work?

I have read that pseudocapacitors are combined of a carbon electrode and a metal oxide one. On the carbon electrode simply a double layer is built up and on the other some chemical actions(redox) ...
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2answers
90 views

Can Light Really be Matter? [closed]

I remember during my early education being taught that light is a form of matter. This has always seemed counter-intuitive to me.
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3answers
949 views

How did physicists know that only negative charges move?

I have phrased similarly another question about how physicists knew that two charges exist, positive and negative. The purpose of the question is not necessarily to educate me historically. It's just ...
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2answers
59 views

What does an oscillating magnetic field produce? [closed]

An alternating current produces a magnetic field. A oscillating charge produces light, which is an oscillating electric, and magnetic field mutually perpendicular to each other, and their motion is ...
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1answer
25 views

Is potential difference the difference in electric potential energy or electric potential?

Referencing the book Physics for Scientist and Engineers, Ninth Edition, the book says that "Potential Difference should not be confused with Difference in Potential Energy." I also reviewed several ...
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1answer
40 views

Why does the heating cord not glow while the heating element does?

This question was in our textbook: 'Why does the heating cord of an electric heater not glow while the heating element does glow when electric current passes through it?'. All I have been taught is ...
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1answer
30 views

How does isolating transformer protect from geting shocked

From what i know, isolating transformer makes it that you would have to touch both ground and phase cables to get shocked, but why exactly is that. There should be some potential difference between ...
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1answer
49 views

Find the electric field of a uniformly polarized sphere

The problem statement, all variables and given/known data We want to calculate the field of a uniformly polarized sphere of radius=R Relevant equations $$V(\vec{r}) = \frac{1}{4 \pi\epsilon_{0}} \...
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5answers
5k views

How did physicists know that there are two kind of charges?

Problems The question I am about to make is either too stupid or hasn't bothered anyone because its obvious because I can't really find the answer anywhere. I am currently studying electricity and ...
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1answer
22 views

Won't the Power be dissipated in the first quadrant of this graph?

In the following picture: In the first quadrant of the V-I graph(for an Independent Current Source, where the voltage supplied is positive on the top) won't the power be dissipated instead of being ...
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1answer
111 views

Why didn't Newton study electricity and magnetism?

This is a soft question about the history of physics. In Newton's time, electrical and magnetic phenomena (such as amber attracting things or the alignment of compass needles) were well known. Yet I ...
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1answer
42 views

Electric potential in a wire

I am slightly confused on the physics of direct electric circuits. Here is what I have been taught: Batteries (sources of emf) provide a constant potential difference between its terminals; ...
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1answer
11 views

Magnetizing a ferromagnetic material.

if i pass a DC current directly through iron or steel or something ferromagnetic, Would that magnetize that material? And would it be magnetized permanently? Another question, does anyone know what ...
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75 views

Discharging a capacitor

Suppose I have a charged capacitor, meaning there's a voltage (electric potential difference), say, $2V$, between its two plates. We don't know the electirc potential of the individual plates, right? ...
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1answer
67 views

Need clarity about relativity/magnetism explanation

Please bear with me - this is not a duplicate question.... From what limited knowledge I have gathered, it seems that when two wires in parallel are carrying equal current, the electrons moving in ...
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1answer
25 views

Could an infinite spinning windmill create endless electricity? [closed]

This is not so much a question about if this idea is physically possibly, but more a question of if it was possible. If a magnet could somehow push a windmill around at a constant speed continuously, ...
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0answers
25 views

Resistance increase with length because of more scattering?

I am referring to one of the answers to this old question. I can't add comment to it because I don't have enough reputation. So here I rephrase the question: does resistance increase with length ...
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0answers
18 views

How are the charges on the plates of a capacitor distributed?

Given a specific overall amount of energy a rectangular parallel plate capacitor stores what number of atoms on a specific plate would have any given specific charge?
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1answer
45 views

Even when the drift velocity of the electrons is very small, how is current in the circuit established immediately?

So I have this question in my textbook and Ive also got it in my test. Ive written a wrong answer. My friend wrote the drift velocities of each particle add up and he got full marks. Is it right? Can ...
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1answer
41 views

Earthing, neutral and Earth's conductivity

Ok so this is gonna be a lot of mini-questions. What exactly is the neutral wire? How does earth conduct electricity for a live AC mains even though its just dirt and stones (it should be an ...
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27 views

What difference does it make if the turns in a tesla coil overlap?

Would a tesla coil in which the primary coil is made by overlapping the turns of the wire work?
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40 views

Geometric frustration in power transmission networks

I read this article concerning the detection of Braess Paradox on power transmission networks: http://phys.org/news/2012-10-power-grid-blackouts-braess-paradox.html Here is a quote from the article: ...
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1answer
12 views

How do ink droplets passing through two charged metal plates become charged as well?

In the working mechanism of an inkjet printer, I came to know that ink droplets in the form of a stream pass through two charged parallel metal plates ( like a parallel plate capacitor) and while ...
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0answers
24 views

Strange roughness feeling on electrically ungrounded surfaces [duplicate]

When I have a device or a surface (typically metallic) that are not well connected to ground I feel a strange feeling when I pass (gently rub) my hand on them. Like the roughness of the surface is ...
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1answer
38 views

Possible reasons of electrocution in a good earthed appliance during sudden power off [closed]

I was working in a industry. When I was using a machine, I felt slight electrical shock at the exact moment when the power supply went off. The machine is properly earthed. In spite of that I got ...
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1answer
21 views

Is peak voltage or peak current kept constant when we change resistance in an AC circuit?

I found online that Ohm's law still applies to an AC circuit and that $V_{peak} = RI_{peak}$. However, I can't seem to find anywhere weather an AC source will : Act as a voltage source and keep its ...
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2answers
40 views

electric current

How can positive charges flow in current? I mean , we know that there is a particle called electron which can move but there is no such positively charged particle which can flow , there can be ...
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1answer
29 views

Voltage in parallel and series connection

In series connection, voltage is said to be different and current constant across the circuit. How does it come about ? Is it due to the accumulation of electrons on one side due to resistors? Or, if ...
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1answer
28 views

Armature of electric bell [closed]

I want to know that why is the armature of the electric bell made up of soft iron ? I googled this out and everywhere it was written that it is because of its propert to aquire electromagnetism but I ...