All Questions
Tagged with electricity electric-current
790
questions
78
votes
11
answers
56k
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Why is the charge naming convention wrong?
I recently came to know about the Conventional Current vs. Electron Flow issue.
Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and ...
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52
votes
6
answers
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Why is AC more "dangerous" than DC?
After going through several forums, I became more confused whether it is DC or AC that is more dangerous. In my text book, it is written that the peak value of AC is greater than that of DC, which is ...
- 2,565
45
votes
5
answers
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Speed of light vs speed of electricity
If I arranged an experiment where light raced electricity what would be the results? Let's say a red laser is fired at the same time a switch is closed that applies 110 volts to a 12 gauge loop of ...
- 4,711
39
votes
5
answers
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If the Earth is a good conductor of electricity, why don't people get electrocuted every time they touch the Earth?
Since the Earth is a good conductor of electricity, is it safe to assume that any charge that flows down to the Earth must be redistributed into the Earth in and along all directions?
Does this also ...
- 1,867
38
votes
8
answers
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Is electricity really the flow of electrons or is it more involved?
I am new to the physics category of the Stack Exchange site. I apologize if my question is wrong, too broad, simple, or worded incorrectly. I am just trying to figure out what is true and false when ...
- 499
25
votes
6
answers
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In aluminum, how does electricity travel through the surface oxide layer?
Suppose I connect a conductive wire (cross section 1 mm$^2$) to an aluminum object. Since aluminum is highly conductive, electricity will flow smoothly inside the object with little resistance. ...
- 4,080
22
votes
6
answers
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In an alternating current, do electrons flow from the source to the device?
If electrons in an alternating current periodically reverse their direction, do they really flow? Won't they always come back to the same position?
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21
votes
8
answers
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Why do we reduce only current to prevent power loss? Why not voltage?
In power transmission lines current is kept low and voltage is kept high to reduce the power loss. This is because $P = I^{2}R$ and $P = VI$. In order to reduce power loss we have to reduce $I$ since $...
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21
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8
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Why do bulbs glow brighter when connected in parallel?
Consider a circuit powered by a battery. If light bulbs are attached in parallel, the current will be divided across all of them. But if the light bulbs are connected in series, the current will be ...
- 351
20
votes
4
answers
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Are the "bird sitting on a live wire" answers wrong?
Long ago, my high school teacher wrote the popular question on board,
"Why doesn't a bird sitting on a live wire get electrocuted?"
He gave us four options (I don't remember all of them) ...
- 1,451
18
votes
5
answers
12k
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How does a wire carry alternating current?
Consider a simple network of a bulb whose two terminals are connected to two wires with open ends A and B respectively
A o--------💡--------o B
Now if a DC ...
- 510
16
votes
3
answers
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Why do birds sitting on electric wires not get shocked?
When we touch electric wires, we get shocked. Why don't birds sitting on electric wires not get shocked?
16
votes
3
answers
27k
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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 ...
- 161
15
votes
3
answers
7k
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Tree vs lightning rod: why does one burn and the other not?
I have this simple question, but I cannot find the answer.
I saw this video about a plane getting hit by lightning. In it, Captain Joe explains why people do not get electrocuted. This has a simple ...
- 314
14
votes
4
answers
26k
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How can one derive Ohm's Law? [duplicate]
I am looking for the derivation of Ohm's Law, i.e., $V$ is directly proportional to $I$. Can someone help me with it?
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14
votes
8
answers
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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 - ...
- 157
13
votes
7
answers
6k
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Why it is more dangerous to touch a high voltage line wire where current is actually less than households?
I have seen that power is transmitted from power stations to households at high voltage and low current to minimize the power loss.
That means the current in the transmission line is less than the ...
- 356
13
votes
2
answers
2k
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Why isn't current carried through a vacuum?
The empty vacuum of space shouldn't offer any resistance to a travelling electron, and so a large collection of electrons should similarly travel through a vacuum without resistance.
As a result, the ...
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13
votes
5
answers
4k
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Watts vs. volts amperes
What I understand:
In simple DC circuits, this is a product of the current and voltage, such that 1 watt = 1 ampere x 1 volt
I understand that a watt is a unit of power (change in energy per unit ...
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12
votes
6
answers
2k
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If voltage is same in two points why does electron move? [duplicate]
We know that at point A and B there is same voltage.Then why electron moves from one point to the another one?
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12
votes
2
answers
2k
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Which electrons kill you during electrocution?
I understand that there are three velocities in play in a circuit (I haven't studied Physics past high school so give me some rope)
v1: the velocity by which the electrical field propagates through ...
11
votes
7
answers
21k
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Difference between current and voltage sources
I am confused about the current and voltage. My intuitive example would be that of a pipe of say water. The diameter of the pipe determines the amount of water flowing per second but the pressure is ...
- 211
11
votes
1
answer
2k
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High voltage power lines - clarification of energy loss
I've been having a bit of trouble understanding the high-voltage power lines. If I was sending power from $A \rightarrow B$, we have:
Ohm's law $V = IR$
Power lost in the form of heat $P = I^2 R$
...
- 914
11
votes
3
answers
5k
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Why high voltage transmission lines?
This is a question which I seem to have tackled multiple times, solved each time after reading a dodgy internet explanation, then partially forgotten about and retackled half a year later. It is time ...
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11
votes
6
answers
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How can current flow through an open wire (like a dipole antenna)?
I am trying to understand how current can flow through a dipole antenna (with length $\frac{\lambda}{2}$ or anything else) which actually is nothing more than an open wire.
Could someone clarify this ...
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11
votes
2
answers
5k
views
Relativistic drift velocity of electrons in a superconductor?
Is there a formula for the effective speed of electron currents inside superconductors?
The formula for normal conductors is:
$$ V = \frac{I}{nAq}$$
I wonder if there are any changes to this ...
- 2,299
11
votes
7
answers
26k
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Why does the current stay the same in a circuit?
I was informed that in a circuit, the current will stay the same, and this is why the lightbulbs will light up (because in order for the current to stay the same, the drift speed of the electrons need ...
- 561
10
votes
8
answers
4k
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Why don't currents due to revolution of electrons add up?
I read that electrons revolving around the nucleus have a current due to the revolution, and it has a formula
$$I = \frac{ve}{2\pi r}$$ where $v$ is the velocity of the electron, $e$ is the charge, ...
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10
votes
3
answers
7k
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How does electricity 'decide' on it's pathway? [duplicate]
I'm struggling to understand the fundamental concepts of electricity, more specifically, the way in which it 'chooses' its optimal pathway.
I appreciate electricity will always choose the path of ...
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10
votes
9
answers
3k
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How does the current remain the same in a circuit? [duplicate]
I understand when we say current, we mean charge (protons/electrons) passing past a point per second. And the charges have energy due to the e.m.f. of the power supply.
Now tell me, if a lamp has ...
- 340
10
votes
3
answers
2k
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Does an electric current flow in an open circuit?
When the positive and negative terminals of a battery is connected through a wire, an electric current flows across the circuit. Generally, electrons are the ones that flow (from negative terminal to ...
- 167
10
votes
2
answers
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How can be the neutral wire at 0 volts when current flowing through it?
Voltage is potential difference, and current flows because of voltage. So if the voltage is zero, how can current flow through the neutral wire.
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9
votes
5
answers
4k
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How does the speed of electricity become the same as the speed of light?
"The field due to the battery sets up a surface charge in the wire. The surface charge is negative near the negative pole of the battery, and positive near the positive terminal, and varies more ...
9
votes
5
answers
3k
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How does the electrical ground rod work?
I was reading this article about shock current path, but it seems to be contradicting answers that I have seen on this site regarding electric shock. I can't find the original question but it was ...
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9
votes
5
answers
4k
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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
9
votes
3
answers
8k
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When the voltage is increased does the speed of electrons increase or does the electron density increase?
I am just a high school student trying to self study, please excuse me if this question sounds silly to you.
I know that current is a product of the speed of electrons and the electron density.When ...
- 1,033
8
votes
8
answers
4k
views
Clarification of the concept "less resistance means less heating" in a wire
So my textbook says that the reason cables that are suppose to carry high currents, are thicker that those that are meant to carry lesser current, is that "less resistance (of the wire) means less ...
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8
votes
5
answers
29k
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How does insulating footwear prevent an electric shock?
The reason I have always heard to explain the reduction of electric shock when we wear insulating footwear goes as follows:
When electricity passes from our body to the ground, an electric circuit ...
8
votes
5
answers
71k
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What is the voltage of an average carpet static shock? Can you make it lethal?
I think I heard somewhere that it was in the thousands of volts, but it had extremely, extremely low amps. Could you somehow transform the current to make it larger or something? Or does the equation ...
- 1,958
8
votes
9
answers
6k
views
Why does electricity need wires to flow?
If you drop a really heavy ball the ball's gravitational potential energy will turn into kinetic energy.
If you place the same ball in the pool, the ball will still fall. A lot of kinetic energy will ...
- 2,009
8
votes
4
answers
2k
views
What's the point of an RMS value? [duplicate]
the RMS (root mean square) value of $f(x)$ is defined as:
$$f(x)_{rms}=\sqrt{\frac{\int^b_a (f(x))^2dx}{b-a}}$$
Why do we do this very specific thing of taking the square, the mean, and then the ...
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8
votes
3
answers
7k
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Low power loss in electricity transmission lines [duplicate]
To reduce the heat lost during transmission of electricity, we say we increase the voltage of transmission, taking the formula $I^2R$ in consideration. Couldn't I consider $V^2/R$? If I consider the ...
- 271
8
votes
4
answers
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Is it possible to flow current in open circuit?
As I know a battery is an example of a closed circuit where it can then produce electricity , electrons will flow from negative pole to positive. A chemistry representation of this battery is for ...
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8
votes
1
answer
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Does rubber insulate lightning more effectively than air?
Last week, an Ars Technica writer was struck by lightning. He says that the 911 operators were concerned about whether or not he was wearing shoes at the time, but he didn't think it would make much ...
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8
votes
5
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Getting Deep into Drift Velocity
We know for a metallic conductor
Current $\frac{I}{enA} = v$ where $v$ is drift velocity , $e$ is the charge of an electron, $n$ is no of electrons per unit volume and $A$ is area of cross section.
...
7
votes
4
answers
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Why don't we get a shock touching neutral wire?
Neutral wire has a V same as ground i.e almost 0. Also it carries some current. So if we touch the wire don't we to become a part of the circuit? Even if we are on the ground and current should flow ...
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7
votes
5
answers
3k
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How does a resistor "know" to increase the potential difference across its ends?
My book says that current has to be constant throughout a simple series electrical circuit consisting of wires, a cell and few resistors, and hence resistors have higher potential difference across ...
- 1,168
7
votes
5
answers
2k
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How to generate electric current without a permanent magnet?
The question is pretty simple:
Can we build a device that coverts mechanical work in electric current1 without employing a permanent magnet and without access to any external source of current?
The ...
- 4,577
7
votes
3
answers
21k
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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 ...
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votes
2
answers
22k
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How do stun guns not kill people?
Now, I've seen a lot of answers to this sort of question, but most of them provide answers that don't actually make sense from a physics perspective.
As an example of such an answer, I've commonly ...
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