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

learn more… | top users | synonyms

0
votes
1answer
175 views

Mean-free-time between collisions and drift-velocity

In a physics text book I need help to make sense of the part highlighted in yellow: This is out of context of course, so just to make it clearer: $\tau$ is the mean free time of the electrons in a ...
0
votes
2answers
17 views

Determine the size of a conductive medium

Are there any measurable characteristics that would allow one to discern the size of a conductive medium? Say I apply the same voltage to a two foot long wire and a four foot long wire. Is there ...
-2
votes
1answer
68 views

Could I materialize electricity making my own lighting?

Where does electricity come from? It comes from very little charged particles inside every atom of materials. Electricity occurs when these little pieces move from one atom to another inside the ...
0
votes
2answers
130 views

Why is static electricity called static?

They called it "static" because "it doesn’t go anywhere". In order to create static electricity, you have to rub two different materials. When you rub them, the electrons move. So, why is it called ...
1
vote
1answer
228 views

The advantages of a dielectric in a capacitor

In a capacitor a dielectric can be placed in between the two plates. I have trouble understanding the points / advantages of a dielectric from what I have read in a text book. The points written there ...
0
votes
0answers
39 views

Ratings for my solar car using brushless dc motor

I need help to decide the ratings of motors,solar panels,battery ratings for my solar car.. I want my solar pannels to charge the battery while the car is running at speed nearly 70-80 km-ph. since I ...
6
votes
0answers
63 views

Weird phenomenon on aluminum laptop casing [duplicate]

A couple of days ago I observed a phenomenon which I'm not sure I understand correctly. My brother-in-law has recently bought an ASUS gaming laptop in an aluminum casing. When the power supply is ...
3
votes
1answer
261 views

The original thorium reactor?

With lunar thorium being common, and heavier than iron or nickel, does earth's core have the the occasional nuclear reaction?
1
vote
0answers
15 views

Are there any pigments which can be altered via the use of electricty?

I was looking at alternative visual output methods for computer, phone and the like and was wondering, are there pigments, Red, Green and Blue preferably, that can have their intensity/opacity ...
1
vote
1answer
63 views

The concept of an electrically short, medium and long transmission line is primarily based on? [closed]

The concept of an electrically short, medium and long transmission line is primarily based on ? A. nominal voltage of the line B. physical length of line C. wave length of line D. power transmitted ...
0
votes
1answer
286 views

How can a negative charge move towards a position of a higher electric potential but lose electric potential energy?

I understand that the equation is: change in electric potential = (negative)change in electric potential energy / unit charge. And I understand that if q is negative, then the change in electric ...
0
votes
3answers
4k views

Why the bulb glows brighter?

If the total current is divided into the branches in a parallel configuration and it is constant in series. How come the bulbs glow brighter when connected in parallel than when connected in series?
30
votes
4answers
3k views

I touched a tree that was touching an electric fence and got an electric shock. How is this possible if wood is an insulator?

I touched a tree that was touching an electric fence and got an electric shock. How was this possible if wood is an insulator? The tree wasn't wet either, and it was a pretty strong shock too.
-2
votes
3answers
99 views

Can you die from a $250 \, \mathrm V$ broken cable? [closed]

I have a laptop power cable that is broken, my dad taped it so it is safe now. I am just wondering: would it have killed me had I touched it? If you could state your qualification/job to show you ...
1
vote
1answer
43 views

How do you work out the energy requirement for a submerged pump?

I was wondering if you were to place a pump in a submerged container and then were to open a hatch allowing water to flood the previously vacant cavity how much energy would be required to discharge ...
0
votes
2answers
75 views

Whats the point in conserving electricity if the AC current produced cannot be stored?

If we cannot save the ac current produced in a battery or some device like the DC current there is no point in conserving it because current once produced should be consumed somehow!!
-1
votes
1answer
118 views

What happens when a wire is conneceted to a plug point directly?

I did it in my school lab and at first nothing happened. Then I jiggled around, sparks flew out with a small explosive sound. It was really cool. The wire ends got burnt and the holes of the plug ...
0
votes
2answers
90 views

Does a rotating DC motor near a TV affects the signals coming in the TV?

In my TV cable the signals were quite noisy so i cut the wire and hanged both the wire parallel to each other. Then the signals became very clear and everything was going alright. Once I was ...
0
votes
1answer
63 views

I wnt to know HOW to create TM, TE, and TEM waves; and is it being used in industry? [closed]

Transverse Magnetic (TM) and Transverse Electric (TE) modes So I'm wholly ignorant of any knowledge surrounding these modes, so bear with me here.. One component is infinitesimally small in the ...
0
votes
1answer
27 views

Does the Magnetic Flux change (at a point) If the wire which causes it was cutted into a half?

If the electric charges move through a wire Does the generated Magnetic flux at any certain point chanage if this wire was cut into a half
1
vote
3answers
122 views

Why are electrons attracted to a magnetic field?

In a cathode ray tube, the deflecting system can consist of either magnetic or electrically charged plates. I understand the fact that electrons are attracted or repelled by the electrically charged ...
1
vote
2answers
41 views

resistivity and temperature scan rate [closed]

100 amperes pass through a copper bar of $5$x$5$ mm cross-section. The resistivity of copper is $1.7 $x $10^{-8}$ ohm-metres. Its volumetric heat capacity is $3.45$ joules per kelvin per cc. ...
1
vote
1answer
30 views

spectrum of discharge of air

Where do the various colors in electrical discharge of air with a high voltage originate from? Are these transitions in ionized nitrogen gas or unionized gas? Are chemical reactions involved? I assume ...
0
votes
1answer
33 views

Formulas which describe Electric power loss accurate

What formulas describe the real power loss in conductors the best? I heard that there are different effects, like skin effect etc. I want to calculate the % the power drops per meter distance. ...
0
votes
2answers
59 views

Is that ground, wall conductive?

If i put my foot exposed to ground and put my finger to the USB power, i will be electrocuted. So the electron(s) from the USB power is passing over my hand, run to foot and go to ground ? As i might ...
0
votes
1answer
39 views

When do I use the various power-related equations? [closed]

Can someone please tell me when it is appropriate to use the equations $P=IV$, $P=I^2R$ and $P=V^2/R$?
0
votes
1answer
99 views

The Electric field & Coulomb's law [closed]

A point charge is moving in an electric field at right angles to the lines of forces .Does any force act on it ? Please explain why.
1
vote
1answer
36 views

Can two transformers used to make tesla coils?

Tesla coils seem to perform the same as a transformers: they use two coils and use magnetic field to transfer the energy. Doesn't using two transformers produce the same result? It doesn't seem to be ...
2
votes
2answers
89 views

Kirchhoff's current law with a nonlinear resistor

It is said that by Kirchhoff's current law $$ \frac{e - v_c}{R_1} = c\frac{dv}{dt} + f(v_c) + i\tag{1} $$ and from Kirchhoff's voltage law $$ v_c(t) = iR_2 + L\frac{di}{dt}\tag{2} $$ from the ...
1
vote
1answer
381 views

Why do the ends of tubelight blink for a considerable time even after the switch is off?

When I switch off the tube-lights , their ends blink for a considerable time. I thought as they were old, there might be some problem. But to my utter surprise, when a new tubelight was switched off, ...
0
votes
2answers
49 views

Power transmission loss in a large circuit

This is a followup question to this question Consider a large circuit like the german electric power transmission network. You have a lot of of people consuming power and a lot of power stations ...
0
votes
2answers
68 views

Kirchoff's loop law

Can any one provide me with mathematical proof of kirchoff's loop law? I am not able to understand from where to start.
0
votes
3answers
65 views

Power transmission in a circuit

lets say you have a battery and a resistance which form a circuit. The electrons flow through the resistance. How can you visualize the flow of energy? How do you visualize the energy field? I ...
0
votes
2answers
48 views

Current lagging voltage by more then 90 degrees

According to Wikipedia https://en.wikipedia.org/wiki/Leading_and_lagging_current An alternating current that reaches its maximum up to 90° behind the voltage producing it is said to be lagging. and ...
3
votes
1answer
180 views

What is fatal? Current or voltage? [duplicate]

I have been searching this answer for quite a while. I asked my physics teacher and he said it is current that causes death. A friend of mine, who is a EE student, and his answer was voltage. When i ...
2
votes
2answers
54 views

Does the conductivity of a wire in a vacuum decrease over time?

Does the conductivity of a wire in a vacuum decrease over time, say over the period of years or decades? In other words: Does current degrade a wire, making it less conductive? If so, by how much, and ...
0
votes
1answer
47 views

Out of phase AC transmission lines in parallel

I've been reading up on power transmission networks and came across this thing. http://en.wikipedia.org/wiki/Quadrature_booster Basically it balances the load between two parallel power lines by ...
0
votes
0answers
25 views

What does it mean to charge a length of wire up to potential v?

I have to study the text "On the Theory of the Electric Telegraph," By William Thomson, 1855. I am having trouble gaining a conceptual understanding of the opening: "Let c be the electro-statical ...
2
votes
2answers
479 views

Why do old transformers make sounds, but new ones don't?

What I think is that maybe insulation is gradually removed between plates, and eddy currents start passing from one plate to another and this produces sound. Am I right?
1
vote
2answers
137 views

Will Positron Cause flow of electricity?

Recently someone told me about antimatter. Antimatter is something that is completely opposite to matter. What I would like to know is let's say this universe was made of Anti-Matter. So since the ...
1
vote
1answer
276 views

Question on Shockley's equation for FETs

I'm currently studying FETs (Field Effect Transistors) in Navy school. What I know so far is that in FETs, $V_{gs}$ is reversed biased, creating a depletion zone. What this means in plain English is ...
0
votes
1answer
91 views

Potential Difference of a wire?

Imagine a circuit with only a 12 Volts battery and a wire connecting the ends of the battery. Point A and point B lies on the wire. What is then the potential difference between point A and B if the ...
0
votes
0answers
19 views

How does the Triboelectric effect work? [duplicate]

The general description for the Triboelectric effect (the main cause of static electricity in everyday life) is that when two certain materials come into contact, electrons are transferred between ...
1
vote
1answer
255 views

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. ...
0
votes
3answers
300 views

Polarization vector of dielectric electrostatics

I know two laws for Polarization vector of a dielectric material $$\vec P = N q \vec{\Delta L}$$ Where $N$ is the number of dipoles per meter cube, $\vec{\Delta L}$ is the vector that represents the ...
3
votes
1answer
159 views

Can high voltage power lines attract physical objects?

An electrician told today in a conversation that 10-60 KV high power lines have a passive property of attracting (pulling towards them) physical objects (e.g. a human body), and that’s what makes them ...
0
votes
1answer
539 views

Electric Field of a circular arc at a point

Given that the circular arc wire with radius 'r' has a linear charge density λ. What is the Electric field at the origin? I took a small segment dy, which is 'θ' above the x-axis with charge ...
1
vote
0answers
117 views

Using a role-play to teach ohm's law

An education research project: can a role-play be used to help understand Ohm's Law? I need to have this analogy checked for scientific validity. A group of 25 primary children will participate, with ...
0
votes
3answers
109 views

How fast does an electron travel in a circuit?

How is it possible to calculate the speed of an electron in a circuit? What factors does it depend on?
2
votes
1answer
174 views

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 ...