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

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1answer
47 views

Can we produce a wave by oscillating current? [closed]

If Radio waves can be generated by using oscillating current so if we changed the properties of current to produce less wavelengths or light waves - I'm not asking about the possibility of producing ...
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2answers
91 views

Charges on capacitor after full charge by battery

When the charging is finished what will be the charge on an ideal parallel plate capacitor ? To be specific what are the charges on different faces of the 2 plates ? All the books say, after 100% ...
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1answer
104 views

Why does transformer winding need large numbers of turns?

In transformers there are large number of turns in winding for both primary and secondary sides around the core. So, my question is why can not we just put one or two turns in winding as we need to ...
3
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4answers
322 views

Avoid static electricity shock on treadmill

I've recently started getting shocked from the treadmills at the gym whenever I touched the buttons on their console. It's getting seriously hard to use them because the shock is not mild it's rather ...
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1answer
28 views

Difficulty understanding the energy transformations during resistance in a circuit

I am currently having problems understanding the energy transformations that occur when resistance in a solid conducting wire restricts current flow. From my understanding, resistance in a solid ...
0
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1answer
71 views

A confusion with solenoidal windings

I have seen in solenoids, toroids, transformers, electromagnets and machines that the core is pretty insulated. Over this the winding coil is wrapped but it is a bare coil (turns are not insulated to ...
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1answer
52 views

Transfer of electrons and static electricity

From what I currently understand about static electricity, electrons "jump" from one object to another, which object loses electrons depends on where it falls on the Triboelectric series. For example ...
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0answers
16 views

Are the effects of faraday's law of induction worth considering in this experiment?

In my intro to physics lab at uni, we did an experiment where we were supposed to measure the amount of kinetic energy and momentum before and after collisions between two carts. For some reason, ...
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1answer
22 views

Short Circuit Fires

I understand that if there’s low resistance, Ohm’s law shows that the current drawn will be very high. However, isn’t resistance what causes heat in a wire? I get there’s a lot of current going ...
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34 views

Open Circuits vs. Charging a Capacator

When you attach a capacitor to a battery via two wires, charge transfer occurs from one of the plates to the other. However, in an open circuit, there is infinite resistance in the dead-ended wire, ...
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1answer
24 views

How many electrons pased in electrical circuit

Assume I have electrical circuit that is connected to 5V power supply and current straight is 1A. How to know how many electrons are passed in single point per hour?
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1answer
39 views

If I lick a 9V battery, why doesn't my tongue noticeably get hotter?

Power dissipated is I^2*R, I don't know the resistance of my tongue so I can't tell how much current goes through my tongue. A resistor I have does get hot and I'm guessing it has a higher resistance ...
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1answer
29 views

Power with varible resistance

I know that P=VI, but what i was thinking about is that if we kept the voltage constant and increased the resistance, we will have less energy consumed by the resistance per second. So, this seems ...
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3answers
56 views

Current and resistance

Why the current is the same at all of the positions in a series circuit??,although there are different voltages at different positions of the circuit. What i know is that as the electron passes one ...
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1answer
11 views

Passive cathodic protection

Trying to understand what is happening when we need protect peace of Fe by placing on it more active metal (for example Zn) like ...
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0answers
32 views

The change of length of positive column in glow discharge

When I was doing the experiment of glow discharge, I lowered the voltage between electrodes and find that the length of positive column will increased quickly around a certain voltage(the interval of ...
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0answers
30 views

If a heater was turned on its' own wire, would heating of the wire cause the resistance to increase, thus the current into the heater to decrease?

I'm thinking not, because; A) It wouldn't make much sense in the real world because you'd need to avoid ever turning a heater towards its own wire, and you'd have to regulate the temperatures of any ...
1
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1answer
34 views

Did I calculate this voltage correctly?

I have just started to learn physics. Please forgive me if I am completely wrong or something, I have just turned 14 haha. I am trying to learn about how to work out voltage for my year 10 exams. ...
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1answer
48 views

Could someone simply explain how a railgun works?

Could someone simply explain how a railgun works? What could possibly accelerate an object that fast in such a short distance? I've heard it has to do with current between two rails, but I simply do ...
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1answer
51 views

Thevenin theorem

Hi i got the trouble and i miss the concept about v out in thevenin i have the circuit like this so i used voltage divider for finding the voltage at point 1, but how to finding voltage at Vo , ...
8
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8answers
442 views

How do electrons know when a circuit is closed?

I was told that electrons do not begin flowing unless the circuit is closed. The electrons from the battery are not in the ends of wire when it is open, apparently, as there is no reason for them to ...
0
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1answer
40 views

How soon would electrons start flowing once I closed a switch on a circuit that was one light minute away from the battery

In a circuit, how do electrons "know" when the circuit is closed? To my understanding, they do not start flowing unless the circuit is closed. How soon would they start flowing once I closed a ...
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0answers
21 views

Hollow metallic waveguides versus optical waveguides versus cables

In almost every physics program, you learn about electricity, electromagnetism, photonics, ... Within the electricity course, you learn about transporting electric energy as electrons through cables. ...
3
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2answers
150 views

What happens in circuits where the propagation time of the electric field is significant?

Kirchhoff's current law assumes "that whenever current flows into one end of a conductor it immediately flows out the other end". I want to understand what happens when we cannot make this ...
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0answers
28 views

What happens to the electrons at junction?

In a Closed circuit at any wire junction, one end of a wire is bound to an end of another wire . Now the Circuit is closed. So the electrons are passing through the wire. Now at the junction there is ...
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0answers
109 views

Why does the characteristic curve (V vs I) for a light bulb backbend?

When teaching Ohm's Law, I have students do an exploration of a small, incandescent light bulb with a low frequency (1-2 Hz) sine wave. It's a simple series circuit of source and light bulb, ...
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3answers
87 views

Speed of electricity in cable [duplicate]

Movement speed of electricity in cable, is same as speed of light in space? In other words, electricity moves in usual electro cable aproximatelly 300 000 km/second ?
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3answers
110 views

Why does AC induction motor rotate the same way?

Suppose an aluminium disc is suspended where it can freely rotate. A magnet is placed above (not touching) the aluminium disc and made to spun. This obvious causes a changing magnetic field. By ...
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1answer
45 views

Why does not the electrons in a conducting the wire end?

What happens to the electrons in a conducting wire, Why does not the electrons in the wire end? I have read answers on the web but have not manage to understand, the free electrons from the ...
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1answer
34 views

Can we use a photon to use it as a changing field in an electric generator? [closed]

In an electric generator we use a changing magnetic field to create electricity. But what if we use a photon's oscillation of EM waves to generate electricity in a metal wire as we do in an electric ...
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0answers
24 views

Would it be possible to transform power using capacitors instead of coils?

Would it be possible to use capacitors to transform electrical tension (up or down), in the following way? Let's say you have a 10v battery, and you want to transform the tension up to 40 v. First, ...
0
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1answer
61 views

Why is the resistivity of a copper cable much higher than copper?

I was looking at the data sheet for a copper cable and noticed the conductor resistance to be specified at around 5 mOhm/m. This is magnitudes higher than pure copper, which has a resistance in the ...
5
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1answer
113 views

Does a Tesla coil work in space?

If I took a Tesla coil into space, and then turned it on near, but not touching metal objects- would charge jump to the metal objects? It's my understanding I wouldn't see a flash, since the lightning ...
1
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1answer
101 views

Will a small magnet affect an insulated computer wire?

I'm designing something that involves a small magnet, probably about 0.5m in diameter, which will rest next to a computer wire carrying data, video, audio, etc. If the wire is insulated (think USB or ...
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0answers
51 views

Capacitors as Energy Wasting?

I am reading a lot of articles about capacitors as the energy storage. Let's consider simple circuitry which contain the battery and capacitor in series. The energy flow from the battery will be ...
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0answers
21 views

Electrostatic concept using for dust attraction

Can I use a charged electrode to attract dust particles from any surface? If yes, then surface should be conductve or non coductive? Or any other ways to do this by electrostatic concept.
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0answers
27 views

Electrostatics effect on resistance values [closed]

Consider two parallel metallic plates separated by a silicon dioxide layer of thickness tox (like a capacitor). In this case I am applying a positive voltage to the top metallic plate. Now due to ...
0
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1answer
27 views

How to configure two infrared light to produce two different intensity

I have two infrared illuminators that have the same properties (same wavelength, same number of leds, same angles, same max voltage and amperage). suppose that these illuminators are attached at the ...
0
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2answers
50 views

How are superconducting magnets powered?

Since the resistance of a superconducting circuit is exactly 0, it would try to draw infinite current from a power source, since P=I^2*R. For a finite power source, I-> infinity as R->0. Correct? ...
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2answers
120 views

Does electricity have mass?

Given a superconducting magnetic coil, such as the ones at the LHC, is there a difference in the coil's mass when it is powered down versus when is powered up? Edit: This has been labelled a possible ...
3
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1answer
187 views

Is it possible to explain voltage and current using the wave nature of electrons?

Assume a battery and resistor are connected in a series. If we double the resistance, the current gets cut in half. This is a macroscopic effect. How do those electrons know that resistance has ...
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3answers
550 views

how does electricity travel?

I have always wondered how it travels. One thing I do know is magnets are used but I am not sure. The type of devices I mean are ultility poles that carry electricity from the powerplant to a house ...
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1answer
81 views

Finding the resistance of platinum wire [closed]

Im currently lost on solving this potentially simple electricty question and was wondering if anyone in this community could hint me or tell me which equations and why these equations would be ...
0
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0answers
17 views

Electrical conductor in a non-conservative electric field

Does electrostatic shielding hold for non-conservative electric fields? I don't think so, but I cannot explain why. Please help.
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0answers
26 views

How does a dynamic electric field change a semiconductors carrier mobility?

Can an electric field that is spatially and/or temporally dynamic affect the carrier mobility in or on a semiconductor and, if so, how and to what degree? I appreciate any help or thoughts you have ...
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0answers
37 views

Analytic solution for AC current density in a wire? (skin effect)

As I was reading about skin effect , I realized that the skin depth $\delta$ is defined assuming a plane wave incidence with a flat media and then the surface current is given by: ...
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4answers
81 views

What instrument should I use to vary the power given to a heating element? [closed]

I have a nickel-chrome wire as a heating element and I want to vary the power given to it to control the amount of heating the wire produces. Which instrument should I use? Please don't give ...
1
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2answers
79 views

Which expression to use for electrical power?

We know that electric power can be written as $P=VI$, or $P=\frac{V^2}{R}$, or $P=I^2R$. But when to use which one? Sometimes two different formulas give different results! Please explain with ...
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1answer
37 views

What's the conversion of ms^-2 to Watts? [closed]

I'm looking to find out how many Watts gravity would be if it were in Watts rather than ms^-2.
0
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1answer
19 views

The speed of an electrical signal through different mediums [closed]

This is sort of a bio physics question and it comes in two parts. The first is: what is the speed of an electrical signal through human nervous tissue? The second part is: what is the speed of an ...