Questions tagged [electricity]

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

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Transformers in Power transmission [duplicate]

Recently I learnt that transformers are used in the national grid to increase the voltage, so we get less current. But my understanding V=IR and by increasing the voltage we get more current, so what ...
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What are the conditions for a glow discharge to occur vs an electric arc to occur in a glass tube?

After the invention of vacuum pumps, people experimented with running electricity in evacuated or partially evacuated glass tubes. In some sources people say this results in a glow discharge and in ...
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Inverse temporal power-law increase of DC voltage under the application of constant DC current

Is there any material in which the DC voltage follows an inverse temporal power-law increase, under the action of a constant DC current? This implies a situation in which a constant current, I, is the ...
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Why doesn't energy supply rate equal the dissipation rate for electrical energy transmissions?

I was recently reading an example which showed that the average rate of energy dissipation due to resistance of the wires that are used in the transmission of electricity from a generator is not equal ...
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Complex Resistance Circuit Problem.. Finding Equivalent Resistance [closed]

I have a doubt regarding this q. how should I approach this q, I want to calculate equivalent resistance.
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What is the maximum possible averge power of the geomagnetic electric generator?

Earth's magnetic field strength varies from 25 to 65 μT on the surface. Therefore, magnetic energy is approximately $V\frac{1}{2} \frac{B^2}{\mu\mu_0} \approx 10^{\left (17,5\cdots 18,5 \right )} \...
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Discharging capacitor: Series vs Parallel

Pretty basic stuff, but to be honest I haven't found a circuit diagram showing a capacitor discharging in parallel. The only scheme I can come up with is shown here: $\color{gray}{\textbf{[ Edited ]}}$...
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Why does an increase in drift velocity decrease electron collision?

The original statement is "The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.". My understanding is, the temperature of a wire ...
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Energy production of solar panels in space with received light [closed]

If there were 47.1% efficient solar panels (the MJ concentrator cells created by the NREL) in space where there is no atmosphere, I want them to generate as much power as possible, so I would like to ...
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Why is mean free time inversely proportional to the electric field strength?

I was looking at the mean free time formula in the Drude model, and realized that it is proportional to 1/E. I am having trouble grasping this idea. I am aware that in practical cases the drift ...
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How does the magnetic force exerted to moving electrons in a current-carrying wire, actually transmit to the wire itself?

From my physics book I understand that the magnitude of the magnetic force is $F=qvB\sin(\phi)$. It is posteriously derived that the total magnetic force exerted to all electrons in a current-carrying ...
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Alternating current changing direction [duplicate]

As we all know AC is is supplied to our homes. As Ac switches direction constantly why only the live wire is hot and there is no negative cycle in nuetra
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Dependence of work done by battery on circuit elements

The formula for work done by a battery is QV, where Q is the charge transferred by the battery. The battery maintains the potential difference between its terminals through oxidation and reduction ...
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How does current actually flow in a wire?

When I was in my school I was taught that the electric field due to the battery is along the wire (from $A \rightarrow B \rightarrow C \rightarrow D $) and these are responsible for electrons at each ...
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Can we imagine having a computer keyboard that recharges itself through mechanical utilization? [closed]

Silly question here. I have a debate with my father, and while I am decent at high school level physics, both he and I cannot determinate through calculus which of us is wrong. Basically, he had the ...
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How do resistors work?

Why is the current before and after a resistor exactly the same? I understand the same amount of charge that enters the resistor leaves, but current is defined to be charge per time. The way I ...
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Static electricity problem

Take the following diagram and explanation: I have two questions: Why is the table tennis ball with metal paint attracted to the positively charged rod. Although the negative charges move closer to ...
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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 ...
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The criteria for zero DC resistivity from Kramers-Kronig relation?

While studying introductory superconductor theory, Neil Ashcroft came up with a criteria for zero DC resistivity as a following: $$\lim_{w→0}w\cdot\rm{Im} \ \it{\sigma(w)}\neq\rm{0}$$ And this must ...
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Hammering to form a magnet

Take the following diagram. I understand that if we hammered the material in a magnetic field, the molecular vibration caused by the shock of the hammer would cause domains to realign, creating a ...
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Why is generation rate equal to recombination rate in extrinsic semicondcutor?

The mass action law states, that the product of electron concentration and hole concentration is equal to the square of the intrinsic carrier density. That applies to both intrinsic and extrinsic ...
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Charge distribution and Shape [closed]

I can't seem to understand why charge accumulates on the sharp points on a conductors surface. I've seen many solutions with math's but I don't understand them and I want a more intuitive explanation. ...
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Is the rheostat in a potentiometer compulsory to have?

I've seen some constructions of potentiometer and all of them had a rheostat. Is it necessary for a potentiometer to have a rheostat? If yes, why?
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Does current flow inside a battery?

When connected in a circuit, does current flow inside a battery. If yes, in which direction?
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Reasoning why the lightning shocks doesnt cause any shocks to a person inside car if the conditon is not fully electrostatic

I am just confirming here how the concept of electrostatic shielding helps in preventing lightining to be not getting into the car inside . So we know car has a metal body outside , so first consider ...
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What happens to a non-conductive material in a circuit?

I recently encountered an electric fence in the countryside. The fence was made from wooden poles in ground which were connected by 3 wires from top to bottom. At one of the poles, however, the middle ...
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How can NO charge carriers exist in the depletion region?

I learned that no charge carriers exist in the depletion region of a PN junction due to the balance between the diffusion current and the drift current due to the electric field created by charged ...
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UV Wavelengths Sparkd [closed]

What UV wavelengths are contained in orange electrical discharge sparks? If the sparks are produced from the slight burning of Teflon covered steel conductor does that alter the uv light frequencies?
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Conventional Current

Recently I learnt about conventional current as well as electron flow, and although electron flow is in the opposite direction to conventional current, we still use conventional current because it ...
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Potential Energy of an Electron inside a circuit [closed]

Why doesn't the electric potential energy of an electron decrease while moving in a circuit away from the negative terminal? This question is concerned with the drop in the potential energy of ...
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How does partialy ionized plasma affect covalent bonds

During partial ionization in plasmas, do diatomic molecules like H2 dissociate into monoatomic states because of the changing states of electron orbitals (exited/ground)?
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A question on the average velocity and acceleration of electrons in a metal conductor and why only the former is zero

While studying electricity, I came across the fact that the average velocity of particles when they collide with other particles is zero as it's totally random. By this logic, shouldn't average /drift ...
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If Electrical flux is no. of field lines passing through the area then why the formula is $E$ dot $A$ (Area)?

I have been taught that flux is no. of field lines passing through the surface. But my question how does the formula for calculating electric flux is matching with the above statements? The formula ...
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No such thing as electrostatic force

Is it true that there is no such thing as an electrostatic force because all charges are moving relative to each other (there is no absolute rest in our universe) so experience an electric force? ...
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The misconceived difference between the electrostatic and electric force

Some sources are saying that electrostatic (coulombic) and electric forces are the same concept in electrostatics (that is the force that an electric charge experiences in an electric field). While ...
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What's the expression relating conductivity with temperature?

In this image, σ is the conductivity, n is the number of electrons per unit volume, λ is the mean free path of the electrons, v (with subscript d) is the drift velocity of electrons, and T is the ...
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What is the difference between electrostatic and electric potential energy? [duplicate]

In circuits what is the difference between electrostatic and electric potential energy? Side question does electrostatic potential energy even exist in a circuit?
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What is the difference between electrostatic and electric potential?

What is the difference between electrostatic and electric potential in a circuit?
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Is charge carrier density an intrinsic property of a material and is thus constant?

I was studying the equation $$I = nAvq$$ where $n$ = the charge carrier density, $A$ = cross-sectional area of the conductor, $v$ = mean drift velocity of the charge carriers, and $q$ = the charge on ...
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Electricity is a wave of electron. But my question is from where the electrons come and where do they go?

We know that electricity is a wave of electrons bit from where do they come and where do they go? Does electricity have mass?
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Why don't we know the electric potential at any point in a circuit, only the difference in the electric potential (voltage)?

Why in circuit analysis, don't we know the electric potential at any point in a circuit?
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5 answers
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Is there a liquid which boils at room temperature and normal pressure, and can we use it to produce electricity?

In many places the temperature difference between day and night is more than 20 degrees C. Max 45 C and min 25C. Can we create a machine which uses a liquid which has boiling point around 25-30 C and ...
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What is a current?

I am confused. One GCSE video on YouTube says it is a flow of electrons around a circuit; while, my textbook says it is a flow of charge around a circuit, carried by electrons. Since charge can be ...
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Voltage Increase in a Circuit When Holding a Motor Still [closed]

My friend and I were trying out a circuit with 6 volts and found that when the motor was spinning slower, the voltage shown on an analog meter was greater. I vaguely guessed that this was caused by ...
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Surface Charge distribution and the direction of electric field inside a current carrying wire

This portion will contain two questions that seems very confusing while studying the electrodynamics. My first question is like this that when we talk about the surface charges on a current carrying ...
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Why doesn't electric flux depend on a charge outside the surface? [duplicate]

Let us assume a gaussian sphere with zero charges inside it, then the flux will also be zero in accordance to Gauss' law. But if we have a charge or many charges outside the sphere such that the ...
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4 votes
1 answer
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What does negative electrical energy signify?

When we derive the formula for potential energy caused by the torque of a dipole in uniform electrical field we get $U = -pE \cos \theta$. And my textbook tells me that the when the dipole is kept ...
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1 answer
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Is this an accurate equation for describing the magnetic force exerted by a solenoid on a ferromagnetic material?

I saw this question, which contained an equation describing the strength of a solenoid: $$F = (NI)^2\mu_0\frac{\text{A}}{2g^2}$$ where: $$F$$ is the force the solenoid exerts on a ferromagnetic ...
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Electric Power and Energy [closed]

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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4 votes
2 answers
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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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