Questions tagged [electricity]

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

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Electric Power and Energy

I was asked a question three times this week and I have been giving the same explanation over and over again, but I am starting to question myself. if you have data on a PV panel production in the ...
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Electric potential vs electromagnetic potential questions

We were all taught about the electric potential $V$, which is defined up to a constant, and can be measured with a voltmeter or an oscilloscope. On the other hand, in electromagnetism are defined the ...
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Does passing an electric current along a strip of metal submerged in saltwater cause anything?

If saltwater corrodes metal. Can we effectively stop this by passing some electric current? Has this been tried before?
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Why is current density in a conductor of uniform cross sectional area constant at all points?

According to what I was taught, if current was dispersed “uniformly,” current density would remain constant. So, in a conductor, the 'current density should be the same at all points.' But, given that ...
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Electric field strength [closed]

I have got a problem to solve which is quite a way out of my understanding and was looking for help: A thin, horizontal, straight rod evenly charged throughout the whole length, which is 2a, is in a ...
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Is electric potential inversely proportional to the voltage at a point?

Consider this simple diagram, where the thermistor's resistance = $500\Omega$. Let's suppose the temperature of the room increases. Then, Electric potential at point ...
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Charges on conducting shell with a conducting sphere inside it

If I have a spherical capacitor which is composed of a conducting sphere surrounded by a conducting shell and the space between them is filled with a dielectric , I assumed that the charge on the ...
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What is the signal velocity in a very thin enameled magnet wire?

I was wondering if in the case of a very thin enameled (i.e. sub-millimeter thick wire insulation dielectric usually made from polyimide) magnet wire the generated electric field of a signal transient ...
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Scaling factor for the right unit?

I have the following equation in front of me $$ x = \frac{\rm constant}{(1+b_1/K_1)^2 (1+(b_2/K_2)} $$ where "constant" is a dimensionless quantity and $b_1,b_2,K_1,K_2$ are measured in mmol/...
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How is surface charge induced on the surface of circuit wires when connected to a battery?

Understanding: I watched the newest Veritasium electricity video and he said that the electric field inside the wires of the circuit that causes the electric current to flow is created by both the ...
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Nickel gauge factor and why is it so quirky?

Hi so I've been researching the piezo-resistance effect and experimenting with finding different metals' gauge factors by applying stress on a wire and measuring the change in resistance however I can'...
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Why is the electric field inside a conductor with charges laying on its surface zero? Is something wrong with my understanding of the concept?

We know that the electric field lines of a unit (point) charge is represented by drawing lines in all the directions radially outwards or inwards (depending on whether the charge is positive or ...
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Would a grounded copper heat sink located near a room's ceiling be an effective way to reduce a room's temperature?

I am thinking about a cheap but effective way to reduce the temperature of my bedroom in my apartment during hot summer nights. I live in an old apartment building and the air conditioner located in ...
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Can I create a planar inductor using salt water?

I know that in order to create an inductor for applications like NFC/antennas or electromagnets, I would need many concentric coils of a conductive material. I was wondering if it’s possible to create ...
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Using the sky and ground as a battery

Since there is a voltage difference between the ground and sky, shouldn't I theoretically be able to light a bulb by connecting one terminal to the ground and raising the other one to the sky (via a ...
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EM energy flux and heat distribution in a cylindrical conductor

Consider a cylindrical conductor made of a single material (say, copper) with conductivity $\sigma$. Assume there is a current through the conductor and, to avoid complications, assume that the ...
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Is it possible to convert static electricity into current electricity?

Generally, static electricity is created by friction between two or more different materials and it doesn't flow through a circuit. On the other hand, current electricity is the flow of electrons ...
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Which type of star is most effective for solar power?

I'm working on a worldbuilding game, and the subject of stars has come up. Imagine you're a species, chilling in the Goldilocks zone of some alien planet, orbiting an alien star. Your people stumble ...
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Is an open circuit completely dead?

Probably the answer should be yes, it's like there would be no electricity source at all. But when I ask what's happening after a switch is turned on, I get the answer that the electricity then goes ...
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What does it mean when we say that an object is neutral?

I am studying electricity and until about now I never really gave much thought to the statement that equal number of proton and electron means neutral charge. Like if we simplify the question and ...
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Direction of current from electromagnetic induction

I've only scratched the surface of electromagnetism but I figured I might as well ask a question. When moving a permanent magnet relative to an electric conductor, a current will form. Say you just ...
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How do I calculate the standard uncertainty? Task on determination of energy gap width of semiconductors

I am creating a report for my physics class and all I have left to do is calculate the standard uncertainty for this formula. $$ \ln \left( \frac{R_{T}}{R_{\infty}} \right) = \ln \left( R_{T} \right) -...
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Working principle of the five(5) needle telegraph by Cooke and WheatStone

So I’m studying the history of telecommunications and came across the five (5) needle telegraph by Cooke and WheatStone. I want to replicate it but can’t get a grasp on the working principles. In a ...
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Why can't we use a slip ring instead of a split ring in a dc motor?

I've been taught that in a dc electric motor a split ring is used to connect the two ends of the rotating coil to two carbon brushes so that The wire does not get twisted and The current passing ...
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Why does electrolytic conductance increase with dilution?

We are only talking about strong electrolytes. According to my book, conductance increases slightly due to dilution. Explanation given by my book: On the one hand, in a dilute solution, the number of ...
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Can we make electron drift velocity faster than light by reducing area of resistor?

We know that $I= nqAV_d$. Can we send high current ($I$) through a "fat wire" (more $A$) then reduce $A$ at the resistor so much that $V_d$ becomes faster than light in order to maintain $I$?...
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Why can't electric field by a single charge be at an angle?

I am having a very difficult time understanding this basic concept of why the direction of the electric field by a single isolated charge is radially outward or inward but not at an angle. I have been ...
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What happens to the positive charges in the cloud after a lightning discharge?

The clouds before a lightning strike contains ice crystal at upper part of the cloud that is positively charged and lower part of the cloud becomes negatively charged. When enough electrons ...
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Is Farady's law valid for conducting loop only? [duplicate]

Is it applicable to a nonconductive loop? What if the loop consists of both non-conducting and conducting paths?
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Does an X-Ray tube have an electric field inside of it? [closed]

I searched the question on the web, but could not a satisfactory answer. Anyway, the question is as follows: The X-Ray tube consists of an anode, which essentially accelerates the electrons, and a ...
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Is the speed of signal transport via electricity as fast as light? [duplicate]

Let us assume a time synchronization system that comprises a sender and a receiver. The sender generates and sends an encoded signal which presents the current time to the receiver periodically, and ...
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Why do we use wires/conductors to transport energy?

I am currently studying Maxwell equations and I learned that copper wires are essentially just wave guides for EM waves. Why do we not use an insulator to guide the wave and transport the energy which ...
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Applying Coulomb's law to find the field strength at a point which is not between the two charges involved [closed]

In most of the questions I encountered, I used the coulombs law only to find the force on a particle positioned between two charges. For the question below, I was not sure whether to multiply the ...
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What happens to the electric potential if the amount of positive charge is greater than the amount of negative charge or vice versa?

In a Lithium-ion battery, the lithium ions are stored in the graphite layer while the electrons remain behind the electrolyte when the battery is fully charged. What if more lithium ions enter the ...
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Why does electricity want to flow into the earth?

If I grab hold of a live wire, current will flow through me and into the earth. If there is an electrical fault in my home, current will flow through the earth wire, out into a ground stake and into ...
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What is electric permitivitty?

I have read 10 different explanations for this in 10 minutes. By definition, to permit means to allow something, but some sites say that it is actually how much a material resists the electric field? ...
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Can positrons flow through matter or antimater or both?

Now, I know that a flow of positrons can constitute electricity. But my question is whether positrons can flow through matter conductors like copper or only antimatter conductors.
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Question regarding power consumption by a device running on electricity

Say I have a device with resistance $R_2$, connected through a wire of resistance $R_1$ to a source providing potential difference $V$. If I close the circuit then current $I$ will flow through, and ...
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What is the resultant EMF when two cells of different EMFs are joined in parallel?

when cells of same emf are joined in parallel then the resultant emf is taken to be the emf of the cells but what if the emfs are different??
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Charge Flow Between Two Spheres Different in Sizes

I'm struggling to understand the following concept: Given two conducting metal spheres of different radii, each have charge -Q (the same charge). If the two spheres are to be connected by a metal ...
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How is ballistic transport detected/measured experimentally?

That is, measuring the current and calculating the resistance for conducting materials of extremely small size and short paths(such as nanowires for example). How is this done in a laboratory?
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Is it actually possible to make an amputated hand move with electricity? [closed]

I was watching a TV show that involved the police tracking down an insane person who was using deceased limbs to perform experiments on. It then cuts to a scene where they find the safehouse with what ...
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How is Lorentz Force $BQv=BIl$?

The formula for Lorentz Force on moving charge is $$F=BQv$$ which for current carrying wire is modified to $$F=BQv$$$$=BQ\frac lt$$$$=BIl$$ Where $l$ is the length of the wire inside the magnetic ...
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Does electrical wire expand when electricity is flowing? [closed]

My home was recently re wired and after seeing the state of the old wiring I was left wondering why I had to replace the wiring after only 12 years. I know some people will say that I've been had off ...
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Potential energy of parallel plate capacitor

I am trying to calculate the electrostrictive strain S on a parallel plate capacitor. For that, I use Young's modulus Y and the formula $$S = \frac{F}{AY}$$ Since the area A and the Young's modulus ...
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Motion of the electrons in a electric conductor when connected to a potential difference?

(I am a beginner in physics, so please forgive me if this is stupid.) Normally, under static electric state there is no resultant electric field existing inside a conducting material. But, when a ...
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Tension along a uniformly charged rod of finite length

I was trying to calculate the tension along a uniformly charged rod of finite length, however, the tension diverged. Translation: 'Let a uniformly charged rod of linear charge density λ and length L. ...
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How to measure water height thickness on infinitely flat surface with constant layer of water?

How would it be possible to measure layer of water on an infinitely flat surface, with every time different, but constant layer of water? I'm trying to measure thickness from $1\rm\,\mu m$ to $5\rm\, ...
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3 answers
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How does the actual power of the device depend on the angular frequency of the voltage? [closed]

The voltage source produces a sinusoidal AC voltage. An electrical device with resistance and inductance is connected to the source. How does the actual power of the device depend on the angular ...
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Relation between electrical conductance of a dielectric layer between two spheres and distance to the spheres

The space between two concentric spheres is filled with dielectric, the electrical conductance of which depends only on the distance to the spheres. Find the law of change of electrical conductance $\...
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