All Questions
Tagged with electricity electrical-engineering
67
questions
57
votes
3
answers
69k
views
Why do we use AC for long distance transmission?
Why do we use AC (Alternating Current) for long distance transmission of electrical power?
I know that AC is such a current that changes polarity (magnitude and direction) and has fixed poles.
- 703
51
votes
8
answers
207k
views
Difference between live and neutral wires
In domestic electrical circuits, there are 3 wires - live, earth and neutral. What is the difference between the live and neutral wires?
As there is AC supply, it means that there are no fixed ...
17
votes
6
answers
19k
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 ...
- 1,657
9
votes
5
answers
4k
views
Why is it easier to raise AC current to high voltage than DC?
In my country (and maybe all around the world I don't know) once electricity has been generated, it is then raised to 200k Volts for transportation.
I know this is to reduce the loss. Given $P=U.I$ ...
- 201
5
votes
2
answers
29k
views
How does current flow from the emitter, through the base and to the collector in a NPN transistor?
So, I understand that for a NPN transistor to work the emitter-base junction needs to be forward biased and the collector-base junction needs to be reverse biased. I understand how current flows from ...
- 59
5
votes
2
answers
135
views
What is the "closed circuit" of a bug swatter racket?
There are bug swatter racket that can kill fruit flies, mosquitos, or flies, if the insect touches the metal mesh.
However, when I look at the construction of the device, the metal mesh is all one ...
- 151
5
votes
3
answers
12k
views
Why and how exactly is electric motor torque limited?
Inspired by this question and specifically this answer to it.
From my experience there's always some very specific limit to how much torque an electric motor can output. For example, an electric ...
- 831
5
votes
1
answer
143
views
What is causing the acceleration of charges in an ideal TEM transmission line?
As I understand, in an ideal TEM transmission line we can set up the telegrapher equations and solve to show that the line propagates voltage and current waves.
My confusion arises when we recognize ...
4
votes
3
answers
5k
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 ...
- 310
3
votes
2
answers
460
views
Physics in the primary coil of an ideal transformer
My textbook says that when primary winding of an ideal transformer is connected to an alternating voltage, an alternating current flows which in turn produces an alternating flux which causes an EMF ...
- 295
3
votes
1
answer
934
views
in photoelectric effect, where do electrons go when they are ejected from metal?
When light shines on a metal, electrons are ejected from the surface of the metal provided the energy of the photons are greater than the work function of the metal.
My question is:
Where do the ...
- 147
3
votes
1
answer
89
views
Railway line conundrum [closed]
I found a wire joining those 2 cement slabs. I wonder what it does. Any ideas?
- 333
3
votes
3
answers
186
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.
3
votes
1
answer
379
views
Which types of collisions contribute to electrical resistivity?
Do electrons only bump with other electrons in a circuit and that only causes resistance? Or do they bump with the nucleus as well?
Here's a post I have been studying recently:
The path of a typical ...
- 165
3
votes
2
answers
197
views
Apparent violation of energy conservation in an electromagnetic transformer system
First of all I would like to say I am not a native English speaker, so there might be some grammar mistakes. Sorry in advance for that!
I have been a whole month trying to understand what is going on ...
- 33