The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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162 views
Why is electrical energy so difficult to store?
Does anyone know a general answer to these questions? (I've asked them together because they're all pretty related, it seems.)
Why is it that we find electrical energy so difficult to store? Do we ...
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3answers
85 views
whether electricity that comes in our home comes directly after generated or first stored and then distributed
Please give answer that, whether electricity in our home comes directly after it is generated e.g. at a dam or nuclear plant or first it is stored somewhere and then distributed as it is needed.
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2answers
91 views
A problem of approximation [duplicate]
Possible Duplicate:
Why are continuum fluid mechanics accurate when constituents are discrete objects of finite size?
When we apply differentiation on charge being conducted with respect to ...
3
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1answer
322 views
Is there something like the Poynting vector for hydraulic circuits?
The Poynting vector is a representation of the energy flux in electromagnetics, showing the amount and direction of power flow at different points in space. In electric circuits, the energy is not ...
3
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1answer
193 views
determination of voltaic cell voltage
if i understood this correctly, the determination of voltage for a specific voltaic (gallvanic) cell is determined only by the chemical correlation between the two metals. is this true?
for an ...
3
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2answers
72 views
What happens to this potential energy?
Let's say I turn on a Van de Graaff which creates a large positive charge. Now let's say I have an object with a positive charge in my hand and I start walking toward the Van de Graaff from $x$ meters ...
3
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1answer
83 views
Why does electromagnetic waves travel slower in well isolated conductor?
Wikipedia writes, that
Propagation speed is affected by insulation, so that in an unshielded copper conductor ranges 95 to 97% that of the speed of light, while in a typical coaxial cable it is ...
3
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1answer
114 views
Does light induce an electric current in a conductor?
I know that electromagnetic waves induce electric currents in conductors and that's the basis for radio, wi-fi etc.
I also know that light is also an electromagnetic wave. So, can light induce a ...
3
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3answers
386 views
Where do electrons in electricity come from?
Where do the electrons come from when an electric generator is making electricity? Is from the air? Would a generator work in a vacuum? Electrons have mass so where would they be pulled from if ...
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2answers
237 views
How exactly does static discharge work?
Assume I have built up a pretty high charge by rubbing the floor or something. I want to understand these situations:
I almost always get shocked when I touch a metal doorknob with my bare hand.
I ...
3
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1answer
149 views
How do bits get transferred over a copper wire?
I've been a programmer for a while, and I've done a little bit of network programming, but I'm wondering, how do bits get transferred over a copper wire?
What counts for a 1 & what counts for a ...
3
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1answer
279 views
The possibility of free electrical energy?
Please excuse my lack of knowledge/understanding.
Question: Why Nikola Tesla's Free Energy concept was never worked upon? Even today.
Context: Now that we know Nikola Tesla was a genius and did ...
3
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1answer
104 views
Theory of Space Charge in a Planar Diode
A planar diode in a vacuum bulb can support current in only one direction. To even get current flowing, you have to heat up the cathode filament to excite the electrons. However, once current is ...
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1answer
175 views
Why does hair stand up when standing under power lines?
My initial guess would be the immense electric field around the lines, that causes hair to get charged and due to each hair having the same charge they start to repel each other.
So what is exactly ...
3
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1answer
802 views
How can a conductor be grounded yet there are induced charges on it?
A classic example for the method of images is the following, quoted from Griffiths's Introduction to Electrodynamics, page 121:
"Suppose a point charge $q$ is held a distance $d$ above an infinite ...
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0answers
38 views
Nature of electricity [duplicate]
Suppose a lightning strikes and there is an iron rod and a coconut tree. How does the electricity know that rod is the least resistant path before hand.
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2answers
249 views
number of electrons my laptop uses in a second
in order to confirm whether I understand the relation ship between amps, columbs and electrons I decided to try out the following.
my laptop adapter's label reads 3.34 amps.
I assume that:
amps are ...
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6answers
3k views
What causes an electric shock - Current or Voltage?
Though voltage and current are two interdependent physical quantity, I would like to know what gives more "shock" to a person - Voltage or Current? In simple words, will it cause more "electric - ...
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3answers
1k views
How much energy was consumed when we turn on/off light?
My parents told me to turn off the light when I am not using it. But I remember my physics teacher told me that the action of turning on/off a light can cause huge energy. I am wondering how much is ...
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3answers
1k views
How can two different 12V batteries have different amperage for same resistance?
My local car parts dealer presented me his inventory of car batteries. One 12V battery had a 'cold crank amperage' of 600amps. The other 12V battery had a 'cold crank amperage' of 585amps. ...
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5answers
435 views
Why doesn't an electron accelerate in a circuit?
Why don't electrons accelerate when a voltage is applied between two points in in a circuit? All the textbooks I've referred conveyed the meaning that when an electron traveled from negative potential ...
2
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2answers
882 views
Why is the steam from cooling towers not used?
If I see the steam coming out of cooling towers at an altitude of 200 meters, I cannot help but think that this energy is wasted. My question is: Why isn't this steam cooled enough to become water and ...
2
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2answers
118 views
What are the current possibilities for large-scale storage of electrical energy?
I'm curious as to how large-scale electrical storage is managed now, how much they can store, how well they scale and for how long (and what is their loss rate).
(I'm not asking about technological ...
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2answers
694 views
Special designs to reduce the electrical resistance of a wire
The numerical simulation of this nerdy question shows that the resistance decreases with the number of nodes along longest side, and converges to a finite value when the # of nodes approaches ...
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2answers
2k 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 ...
2
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2answers
292 views
Can a camera flash light near high voltage wires create medium to pass electricity?
I found a story of a boy who took a picture with flash light near 40,000 voltage lines. When it flashed, current came to his camera (as a spark may be) and passed through his body making him dead.
Is ...
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4answers
2k views
Understanding the relationship between electricity and magnetism
I keep on hearing that magnetism is just another form of electricity and vice versa. If that's the case why can't we use magnets as batteries, and why aren't my batteries magnetic?
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1answer
628 views
Current from induced emf
If the induced emf in a circuit is negative, and current from this emf is the emf over the resistance, what happens to the negative sign in the induced emf when solving for the current? Surely there's ...
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3answers
604 views
is it possible to flow current in open circuit?
First , i don't know much about chemistry and physics. I'm just a graphic designer but i have this question in my mind. I'm sorry if this question is too basic and use 'generic' language.
As i know ...
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4answers
606 views
Effects of a Coiled Cable
Okay, I've got a little bit of a layman's question here.
We're doing a bit of spring cleaning in our office and we've found a cabinet with boxes upon boxes of stored wires, so naturally, this ...
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5answers
980 views
How can I prevent being zapped by static electricity every time I touch a doorknob or handle in the office?
I don't know what it is about this office, but it seems everything I touch (doorknob, bathroom faucet, edge of kitchen sink in the break room), I get zapped by static electricity. It's getting old. ...
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2answers
313 views
Why doesn't a phone charge faster, rather than slower when it is in use
In Physics class, we were building parallel circuits, and as more lights were attached in parallel, they got brighter (as more power was being provided to the lights, and the resistance decreases). ...
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1answer
19 views
Why does increasing the temperature of a thermistor decrease it's resistance?
Surely, upon an increase in temperature, the atoms within the thermistor would vibrate with more energy and therefore more vigorously, hence making the electrons flowing through the electric circuit ...
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3answers
66 views
computer vs heater coil comparison
If I have a computer and a heater coil that consume exactly the same amount of energy, which would be more efficient at heating my room? This is assuming that they both have the same fans and heat ...
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3answers
303 views
How does energy depend on frequency in an alternating current circuit?
In what relation is the energy input in an alternating current circuit to its frequency?
I'd guess I have to compute something like
$$E=\int P(\omega,t) dt=\int U(\omega,t) I(\omega,t) dt, $$
but ...
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2answers
3k views
Are all metals good conductor of electricity?
I am writing an article for kids, which is on conductors and insulators of electricity.
If I make a statement that "All metals are electrical conductors and all non-metals are electrical insulators" ...
2
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2answers
138 views
Differences In Potential Equations
Could someone please describe the differences between the uses each of these potential equations:
Potential due to a point charge:
$V = \frac{k \cdot q}{r} - \frac{k \cdot ...
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2answers
1k views
How do I join two co-axial cables?
I'm trying to join two ends of co-axial cables. I've managed to connect the two ends of copper wires but still the signal response is very low. When I try to stretch the cable signal gets good. Why ...
2
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1answer
811 views
How fast do electrons move through a conductor?
If I apply $1 \text{ V}$ across a $1 \text{ }\Omega$ resistance, I'd get $1 \text{ A}$ flowing. $1 \text{ A}$ is defined as $1 \frac{\text{C}}{\text{s}}$, and $1 \text{ C}$ is equivalent to ...
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3answers
75 views
Producing electricity from all wavelengths of electromagnetic spectrum
Is it possible to produce electricity from all wavelengths of electromagnetic spectrum beside visible light ?Like using gamma rays or x-rays .
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1answer
102 views
Does electric potential have a temperature?
When I took my first thermo class a tucked away chapter introduced Exergy in terms of electrical energy, meaning that the amount of electrical energy you could get from something is functionally its ...
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1answer
593 views
Can Gases conduct Electricity?
Liquid electrolytes ionize and hence a current can pass through them. So if a gas can ionize, can it conduct electricity too? If so, what are a few such gases?
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1answer
191 views
Could we build a super computer out of wires and switches instead of a microchip?
I thought of this question; would too much wiring make a computer burn down? Or can you build an actual full-speed supercomputer computer using switches and wires?
In other words, could simply adding ...
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2answers
153 views
Can wireless power transfer harm organic life by anyway?
Now, humanity can beam 50-60 watts power through 10 centimeter-thick concrete block. Can such wireless power transfer harm us by anyways?
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2answers
550 views
is the voltage drop of a battery that is being short circuited the same as the battery's advertised voltige
So I know this is a pretty fundamental question, but I'll ask it any way. lets say you have a 12V battery, and the positive is connected to the negative directly by a wire with negligible ...
2
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1answer
363 views
Electrical flow in a simple parallel circuit
I'm having trouble understanding something in one of my text books:
Let’s have a look at the implications of each circuit configuration.
Figure 3.13 shows the Conventional representation of a ...
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1answer
143 views
What's the second terminal in corona discharge?
I don't get corona discharge. There's an electrode (say naked high-voltage wire) and a current develops from that wire and ionizes gas (air) on its way.
But where does this current go? What's the ...
2
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2answers
2k views
What happens if a wind mill rotates in opposite direction?
Suppose if a windmill is made torotate in clockwise direction and due to air flow if it rotates in anti clockwise direction then does it produce electricity?
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2answers
203 views
Small scale water power, how does water volume and hight convert into electric energy?
I was playing a little bit with the basic physics behind water power production but I can't get the numbers right.
Let's say that I put a windmill that pumps water into a watertank on the top of my ...
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4answers
790 views
Calculating current used by individual resistor?
I just recently finished a test on Physics, and when receiving my scores back I missed a question. Here's what it was if I can remember it correctly:
Three resistors (10.0, 15.0, and 6.00 ohms) ...
