Questions tagged [electricity]
The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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Salt and electricity
Recently, I did an experiment with salt and electric current. I set up an open electric current in a used battery holder where the missing part of the circuit is two metal plates. I then fill this ...
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1answer
24 views
Forces Acting On a Bar of Magnet Inside a Solenoid
If you have a solenoid placed like this:
and you drop a magnet inside the coil will the change in acceleration of the bar of magnet inside the solenoid coil over change in time be 0? i.e. will the ...
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Which weight would be necessary to power a computer with this system? [on hold]
Let's say I install such a system:
in a corner of my room, that produces energy in a similar way than grandmother clocks, connected to an alternator (or any other system that transforms mechanical ...
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1answer
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Does potential difference depend on the size of an object
Let's say object A has received a number x of electrons and is now at a 1v higher potential relative to a neutral ground.
Now if object B which is 2 times bigger than object A receives the same ...
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What are simple comparisons of energy draws? [on hold]
I have recently attended a Bitcoin mining conference. Some of the attendees were specialists in energy with their business being oriented around building data centres or catering to the needs of data ...
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Need Help with Proving Faraday's Law of Electromagnetic Induction with Experiment Results [closed]
I have recently conducted an experiment measuring emf over time and magnetic field strength over time as a bar magnet fell through a coil. The magnetic field was measured by pointing a magnetometer to ...
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47 views
Electricity cost of a kettle [closed]
A 2.5kW electric kettle has an efficiency of 95%. (95% of the electrical energy supplied is converted to heat in the
water.) Electricity is charged at 22 cents per kWh.
How much money would the ...
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1answer
35 views
Current densities in a 3D object
What is a smart way to calculate current densities in 3D objects with unorthodox boundary conditions?
For example, J(x,y,z) in a cube with constant resistivity with applied voltages Va in a vertex ...
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1answer
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How does 'conservation of law of energy' work in an open circuit connected to a hydroelectric generator?
I am trying to relearn high school physics and having trouble visualizing electricity in an 'open' circuit.
I am going to use layman terms so i don't confuse myself! Apologies in advance if i am ...
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1answer
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Electric power correction
The electrical energy is defined as: $$ E(t) = Q(t)V(t)$$
The general definition of power: $$P(t)=\frac{dE(t)}{dt}$$ and becomes $$P(t) = \frac{dQ(t)}{dt}V(t) + \frac{dV(t)}{dt}Q(t) = I(t)V(t) + \...
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Resistance and electricity
strong text
In the answer to this question, it stated that the current would remain unchanged and I was wondering why the current would remain the same for the portion of the wire even though the ...
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1answer
31 views
Electromagnetic Induction - An Experiment
I am currently working on a personal project where I am investigating Electromagnetic Induction.
My set up includes two loops - one primary and one secondary. The primary loop is hooked up to a ...
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2answers
56 views
Could you transmit electricity wirelessly?
Since you can wiggle an electron to get a radio wave And if you 'wiggle' it fast enough you get higher and higher frequency right? So couldn't you just broadcast an electromagnetic beam or whatever ...
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4answers
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Frequency of light versus frequency of electron vibration
I've been trying to understand photons and light, although entirely conceptually (layman with not much of a background here, but I really want to understand this a bit better) and there's a couple of ...
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Planck's Constant to the Kibble Balance
A tad confused on how the Kibble balance actually relates to the Planck Constant. There's most likely a very simple relationship that I'm missing (I feel this is a stupid question ..)
If the Kibble ...
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4answers
49 views
Can a series of capacitors convey alternative current?
Since capacitors allow charges to pack on the negative plate, there is some current flowing for a short time. Also the dielectric does not prevent the EMF otherwise there would be no voltage at any ...
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Electrochemistry heat generation
In electrochemistry the Nernst equation says Gibbs=-nFE and the reversible heat=TdS= T*partialE partialT * -nF but the Bernardi heat equation is q= I(Voc-V+TpartialE partialT) when we know that the ...
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Why can't we harness the energy of lightning? [duplicate]
Studying capacitors, this question struck me. If we know that there is a large potential difference between the ground and the atmosphere, why dont we use that to power our machinery? I understand ...
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2answers
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Contradicting relation between total power consumed and power consumed by each individual resistor in series and parallel configuration
In a given series configuration of n resistances of equal resistance r, I derived the relation bewteen total power and individual power consumption as follows:
P(Total) = I^2 * R
R= nr (equivalent ...
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2answers
35 views
Skin depth; EM wave and AC
When I google skin depth, I get the following definition,
Skin effect is the tendency of an alternating electric current (AC) to
become distributed within a conductor such that the current ...
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2answers
49 views
Inductor in a DC circuit [closed]
I found this question,
I don't understand how could the current through 2R ,immediately after opening the circuit, be less than when the circuit is closed!
Shouldn't be an emf from the inductor that ...
1
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1answer
40 views
Why is the electron mobility 'irrelevant' in metallic conductors?
This Wikipedia article states in the introduction
Conductivity is proportional to the product of mobility and carrier concentration. For example, the same conductivity could come from a small ...
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29 views
Do charges move on the surface of conductors for steady direct currents?
The answers in this post suggest charges move through the bulk of conductors, not only their surface, when dealing with direct currents.
However, suppose we have a steady direct current, this steady ...
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0answers
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Speed of a current passing through a wire [duplicate]
The wire is at 50hz, and is an aluminum alloy (AAAC 1120). Resistance in the wire is at 0.0897 ohm/km. So for a length of conductor 135km long, the resultant resistance will be 12.1095 ohm. It's AC ...
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Proof that $\text{Magnetic Flux Density} = {\text{Magentic Flux} \over A\sin(θ)}?$
Problem : How is $\text{Magnetic Flux Density} = {\text{Magnetic Flux} \over A\sin(θ)}$ (this is the formula my text book has given me)
Where $θ$ is the angle between magnetic flux lines and plane
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1answer
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Electric Field inside an ideal conductor
I have some doubts about the electric field inside an ideal conductor (let's call it E). Precisely, I have read two different descriptions
1) On physics books I read that the electric field inside in ...
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1answer
44 views
MW@kV conversion
First, I'm sure this question is way too easy for this forum but I didn't find a better one. I'm having an argument on the following and we'd like to settle it officially.
On a website about Diesel-...
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1answer
32 views
Magnetized Steel wire around Soft Iron Core
We all know that a current carrying solenoid of copper is a weak temporary magnet and if we wrap it around a soft iron core it becomes a temporary strong magnet i.e. the iron core magnifies the ...
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1answer
22 views
Drawing conclusion from the given information about force of electrostatic interaction [closed]
I am not able to understand why the values of measured theoretically and experimentally would be different and even if they differ how does it affect if they are like charges or unlike.
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Is magnetic flux depending on the orientation of ferromagnetic rotor?
I have attached a picture of Reluctance motor setup. When I turn on the AC source, Magnetic flux lines will build up. My question is, will the magnetic flux will be a function of the angle turned by ...
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How do thunderstorms generate ionospheric potential?
In all the explanations of how global electric circuit on Earth works, I've always encountered statements like "thunderstorms generate ionospheric potential" (which is about 250 kV).
E.g. here: https:...
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Electronic explained by hydraulic
Where I can find a book or website (or any source) which contain many electric compounds (capacitor, transistor, diode … and more) explained by a flow of water (hydraulic analogy) which is more easy ...
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1answer
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Why can't we generate electricity from Earth's electric field?
This may be very silly, but I need to understand this to get my concepts right.
Consider the fact that the electric field b/w the Earth's surface and the ionosphere is on an average $100$ V/m, then ...
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How can I make a homemade hemholtz coil?
For a project, I need to make a hemholtz coil capable of generating uniform magnetic fields of between 0.0 and 0.4T and which allows the user to control the strength of said field at any given moment. ...
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2answers
42 views
What makes electrons 'more free or less free' to move around?
I understand that conductors allow electron flow because their valence electrons are 'free' to move around.. But what exactly determines this 'freeness' and the lack thereof that separates conductors ...
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Potentiometer analysis
As I was studying about potentiometer I came across how to use it to compare emf of two cells.
It was written my text book that if current I flows through potentiometer wire then
$$\mathcal{E}= v\...
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Why are solar panels still efficient with cloudy weather?
Recently I did an experiment in college involving solar panels.
I noticed that the weather suddenly changed from sunny to cloudy, however the output of the solar panels dropped only very little.
My ...
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0answers
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Lightning through Helium gas
Assuming that some distant planet had an atmosphere of helium and(due to extremely cold temperatures) a "water cycle" of neon, what would happen if the theoretical neon clouds acted in a similar way ...
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What is the theoretical maximum efficiency of converting electricity to EM radiation? Is there such a thing?
It turns out LEDs can have an efficiency of more than 100%, i.e. they output more light energy than electrical energy goes in. The 'missing' energy is taken from their thermal energy so the LED cools ...
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Concentric cylinder cell arrangement
If i have a concentric cylinder cell with a dielectric fluid in between, would the electric field homogeneity be affected whether i make the internal or the external cylinder the anode and the other ...
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1answer
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Is the current on one side of the bulb more than the current on the other side of it?
Go easy on me if you find this question stupid, just another high schooler here.
So here's what I am thinking.A battery "pushes" electrons through a circuit due to the electric potential difference ...
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2answers
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How do flowing electrons generate magnetism?
I am trying to understand what magnetism really is, beyond just a field, an attractive or repulsive force. I would like to know: how do flowing electrons (e.g. electricity) generate a magnetic field?
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Electrostaic bonding of materials
How can you get plastic wrap to bond with paper, and maintain the bond? Once the electrons are exchanged, the bond fails. How can this be prevented from happening?
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1answer
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Electrical impulse through a mic [closed]
For a typical mic a singer uses to sing on the stage, how much electrical current is generated when the sound gets converted into electrical impulses? Can I get an electric shock from the energy ...
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1answer
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Can temperature difference in a conductor induce charge in it?
Assume a metallic rod which is heated on its right end to maintain a constant temperature gradient in the rod.
Now if we take any crossection in the rod,the right side part of the cross section has ...
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2answers
69 views
How do elecrons move?
Do elecrons move from low to high potential or they move due to attraction by positive charge?
Or is it something else, what actually happens in flow of electricity.....the concept is just so ...
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1answer
75 views
Why connect plug wires in a certain way when polarity changes in AC anyway? [duplicate]
In AC systems the two wires of a circuit alternate polarity many times per second. So positive and negative switch, half of the time a wire is positive the other it is negative.
So why is it ...
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Doesn't electrical energy gets lost due to slackening of local electrical wires hinged between street electric poles?
I am talking about the wires which get somewhat loose or somewhat like parabolic shaped due to earth's gravity.
What I think is due to slackness of wires there is a net increment in resistance which ...
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Stability of a dipole magnet undergoing eddy current braking in a cylindrical tube
Consider a cylindrical dipole magnet with strength $B$ undergoing eddy current braking in a conductive cylindrical tube with the axis of the magnet aligned with the axis of the tube.
The magnet ...
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3answers
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Found some errors in some equations of electric power. What is the actual problem?
I think the following two equations are incorrect when $I, R$ refers to current and resistance respectively and $V$ refers to potential in the difference of potential of the two sides of the resistor
...
