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

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29 views

How to check the ohmic contact to the film?

I have a thin semiconductor film deposited on an isolating substrate. I would like to check different metals to find out do they form the ohmic contact or Schottky barrier. What is the best way to do ...
11
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8answers
10k views

What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)?

This is a confused part ever since I started learning electricity. What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)? All of them have ...
3
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2answers
202 views

Loopy lightning

What causes lightning to follow the path it does ? picture from BBC news: http://news.bbcimg.co.uk/media/images/62891000/jpg/_62891901_untitled-1copy.jpg main page: ...
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1answer
64 views

Ambiguity on the notion of potential in electrical circuits?

As everybody else I have been taught elementary electrical circuits from secondary school to engineering level in analog electronics at university. Invariably, the notion of potential used to ...
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0answers
31 views

Make an Electric motor work with help of 4 magnet wheels? [closed]

I am working on a car prototype that should work on the electricity that it generates with the help of magnets. The strong magnets will be fixed at the wheels. A Coil of thin copper wire(solenoid) ...
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3answers
286 views

Potential difference (PD) and electromotive force (EMF) in terms of electrons?

I am trying to understand potential difference and electromotive force in terms of electrons. In the above 3 circuit diagrams the red shows (what I think to be) the distribution of electrons ...
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1answer
58 views

Is it possible to generate electric energy from the radiation of radioactive materials

I wonder if it is possible to generate electric energy from the radiation of radioactive materials like nuclear waste? If it is then wouldn't that also mean that it could be used as an energy source ...
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1answer
40 views

transfer of electricity through electromagnetic waves

Is it possible to transfer electricity from one place to another without the help of physical wires.
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8answers
8k views

Since cables carry electricity moving at the speed of light, why aren't computer networks much faster?

Why can't cables used for computer networking transfer data really fast, say at the speed of light? I ask this because electricity travels at the speed of light. Take Ethernet cables for example, I ...
0
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2answers
45 views

Can I calculate the current of any setup with capacitance by the same formulae?

There are known formulae relating a capacitor's voltage and current in its classic form (battery, wires, a capacitor circuit), but what if we had a charged plate (-ve), then we put on one of its ...
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3answers
101 views

Current through two inductors after a long time

I'm having trouble with visualizing the following problem, which is asking me for the final, steady current in both inductors $L_{1}$ and $L_{2}$. I was thinking that after a long time, essentially ...
2
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3answers
488 views

How does the movement of electrons produce radio waves?

I'm mostly wondering about radio frequencies. I understand that voltage is the movement of electrons, and that the antenna acts as a light bulb, emitting at radio frequencies, following the reverse ...
3
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3answers
14k views

Would you die if you put your hands on a powerline?

You know how birds perch on powerlines without getting electrocuted? What if by some chance that I find myself falling and I grab on one of them? Let's say both of my hands are on the same line, would ...
0
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1answer
71 views

Why Change Of Magnetic Flux Induces Current In circuit?

Why change of magnetic flux with the time through a coil induces current in it? Please tell me that what happen to charge in the coil if the magnet or electromagnet wave around this? Also, why a ...
2
votes
2answers
96 views

Drude model: A concerning approach to $\tau$ hurts Ohm's Law

Here's the question. Between two points, $a$ and $b$, if an object is accelerated between them, it will cross the distance between them in time $t=\sqrt{2\frac{d}{a}}$. So, if the acceleration is ...
0
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1answer
50 views

Electricity supplication [closed]

Is their any reason I can search up as to why electricity is generally harder to inaugurate in regions of vast inhabitability?
2
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1answer
109 views

If light is an electric and (magnetic field), how can it be absorbed?

I was wondering how light or any electromagnetic radiation can be "absorbed" if it consists of electric and magnetic fields. For example if there is a charge at point A, and the light reaches point ...
1
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0answers
24 views

Does the skin effect and the proximity effect cancel each other out?

I'm interested in how the Skin Effect and the Proximity Effect interact with each other. From what I can understand: The Skin Effect is when AC current 'collects' on the skin of conductors due to ...
1
vote
1answer
134 views

The workings of the Hall effect?

I want to ask about the workings of the Hall effect. Why do the electrons come to rest on the edge of the wire? The magnetic field pushes them up, and the electric field pushes them forward. Shouldn't ...
3
votes
2answers
171 views

Why does smashing a TV remote load its batteries?

Many times I had the same problem: my TV remote's batteries were too weak for it to operate, but then, when I shook the remote a bit and smashed it on my palm, somehow the remote regained its ability. ...
2
votes
4answers
96 views

Why does a Resistor cause a potential drop?

I need to know the underlying physics of what exactly happens different with the electric field in the resistor than in superconducting wires. Why is it that when I connect a resistor, potential ...
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5answers
5k views

Why is the charge transferred by electrons and not by protons?

charges are transferred by electrons which we all know but why it cant but it cant be transferred by protons.Well i searched on google where i found similar questions already being asked on many ...
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1answer
42 views

Electricity production

Are there alternate means to produce electricity than magnetic induction? I observe that all places this method is used .Do other methods exist even if this being the most profitable way.
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3answers
199 views

How do substances with like charges repel each other?

I have read in a number of places how substances with opposite charges attract each other: The excess electrons in the one substance repels the electrons in the other substance so that they move away ...
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3answers
72 views

Basics of Current Electricity

I have certain questions which confuse me a great deal. I want to have a very basic and clear idea about some concepts. Here it goes: 1) I am really confused on how a battery actually works. The very ...
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1answer
38 views

In Leyden Jars, how does the outer metal get charged?

In a Leyden jar, I have read that a charged object is brought in contact with the conductor in contact with the metal inside the jar, thus giving the inner metal a similar charge. And the metal ...
0
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3answers
414 views

Why does resistance increase with length?

This is for the case of wires only (pipes are easy). I see that if I place a 9-Volt (constant) battery across any wire, the current is proportional to resistance. I don't understand why, for a ...
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0answers
14 views

Why is low resistance beneficial to ion exchange membranes?

http://scitation.aip.org/content/aip/journal/jcp/139/11/10.1063/1.4821161 The article states that the graphene filter has a much lower electrical resistance than existing ion exchange membranes, ...
2
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2answers
3k views

Microwaves vs Gas or Electric Coil heating of a water boiler in a typical household

Wouldn't it be more energy efficient and or safe to use microwaves to heat our home's water boiler instead of using dangerous gas or hot electric coils that could catch other things on fire? I'm kinda ...
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1answer
56 views

Repulsion and attraction of electric currents

Now, I understand that when a an electron travels, it creates a magnetic field. If you put two wires with current traveling in the same direction they repel, and current traveling in opposite ...
7
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6answers
21k views

Why does my wife's skin buzz when she's using her laptop?

When my wife uses her laptop, if I touch her skin, I can feel a buzz. She doesn't feel the buzz, but she can hear it if I touch her ear. So I'm guessing it's a faulty laptop, and she's conducting an ...
0
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3answers
70 views

The measurement of electricity

I'm a student trying to understand electricity. As I learned from school, electricity is the flow of electrons, but I'm confused about the measurement of electricity. As I learned, voltage is the ...
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3answers
4k views

use of Mobile phone on Petrol pump

I was trying to find out the cause behind the Explosion at petrol pump due to the Mobile phones but eventually it turns out it is not Radio Frequency which may cause the explosion rather it is totally ...
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3answers
1k views

Questions about voltage

For some reason, I feel like the concept of voltage is escaping my grasp. I've done much research on these forums and through texts, and come across answers that seem quite well thought out, but still ...
0
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2answers
138 views

Heat loss using alternating current

I am looking for somebody who can explain this to me. As I have read in physics books, the Joule-Lenz Law (Joule effect of heating) is represented by the formula: $$ W = I^2Rt $$ which can be ...
20
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1answer
1k views

Is it possible to overload a lightning rod?

A couple of weeks ago we had a big storm roll through the Chicago area. I watched as the city's skyscrapers were struck multiple times by lightning throughout the night and told my coworker about it ...
2
votes
1answer
77 views

Why is the perfect obstructor the perfect conductor as Heaviside 'believed'?

How might one consider a conductor to be an 'obstructor'? Might the strength of the 'skin effect' of a conductor be in direct relation to conductance? And how does this relate to insulators, as ...
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3answers
87 views

What really is resistance? How does it generate heat?

OK I know that R= V/I. I also know that R = ρl / A But what I want to know is that what really causes resistance? Is resistance equivalent to force? or is it just a constant? Also, what causes ...
0
votes
1answer
33 views

Convert pressure to energy [closed]

I read a little about electricity being created from pressure, Piezoelectricity. I'm still pretty newbie about it though. Let's say I want to charge a battery from that technique, using my hands to ...
1
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2answers
145 views

Can we pass electricity through air?

Electricity: I was wondering, whether we can pass electricity through air over a distance of 100 meters or so as electricity means the flow of electrons and we have seen the discharge or movement of ...
2
votes
2answers
214 views

How does AC current flow in an open circuit?

In common house hold wiring we have the hot lead, neutral and ground. If the hot lead in electrical wiring contacts earth ground (perhaps though a short circuit in the chassis of a device) then the ...
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3answers
415 views

How exactly does WiTricity's wireless power transfer using resonance work?

The WiTricity group has made a lot of buzz but no internet article explains the exact method that they are using. Does any one know how it works?
0
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1answer
82 views

Application of Displacement Current

I'm reasonably happy with the derivation and results of displacement current, however, I'd like to be aware of a few practical applications of this idea. So far, the only one I'm aware of is when ...
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0answers
45 views

Numeric value of the electrons drift velocity in superconductors

Somebody knows the numeric value of electrons drift velocity in superconductors? How this value depends from the used superconductor material? What's about the current? Since the electrical resistance ...
0
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1answer
32 views

Natural electricity in the atmosphere - lightning

If air is such a poor electrical conductor, how can lightning be produced that appears to travel through it?
8
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4answers
206 views

Temperature and resistance?

Why does resistivity increase with temperature? The explanations I have heard so far are that increasing temperature increases vibrations in the lattice structure resulting in the number of ...
2
votes
1answer
42 views

Protect drone from lightning [closed]

I am designing a dirigible, robotic drone. It is basically a polyurethane airship, approx 3.6 m length and 2.1 m diameter. I am worried about lightnings: as far as I know, a Faraday Cage should be ...
2
votes
1answer
145 views

When we get an electrical shock, the ciruit is incomplete but still the current flows, why?

If we touch the live wire and ground at the same time, we will get a shock. But the current goes from live to ground and not to neutral i.e, circuit is open. Then how can we get a shock? This is ...
5
votes
4answers
6k views

A circuit with no voltage difference, but current flowing

From Michael on Skeptics Stackexchange: How about a wire that's grounded? Safe to touch, right? WRONG. ...