Questions tagged [electricity]
The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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Kirchhoff’s rules
Can Kirchhoff’s rules be applied to simple series and parallel circuits or are they restricted for use in more complicated circuits that are not combinations of series and parallel?
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Increasing the Voltage, Ohms law, what am I missing?
There is one thing in Ohms law I am missing I think.
Lets say you have a simple circuit with a single resistor, $R$. We apply voltage $V_1$ to it, by Ohms law the current is $I_1=V_1/R$.
Now we ...
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What would happen if you drew electricity from a magnet in orbit?
So suppose you had a big, dense, heavy magnet that we got into orbit. In its path of orbit would be a tube of copper wire running all the way around the planet. So it would be orbiting the planet, ...
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Why isn't steam turbine condensation carried out in spare boilers?
Why do steam turbines at the power plants have to transfer heat to the environment or to so-called cooling towers? Why not reject the heat through tubes carrying the steam into another boiler (...
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Position of a charged particle in a radial electric field
I am trying to work out the radial position of a charged particle in an attractive radial electric field due to a fixed point charge.
The acceleration of the particle is C/(r^2) where C is a const and ...
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When an iron core is placed in a solenoid, why does the current increase?
Does the flux of the coil cut the soft iron core and generate emf in it? I am confused over the fact that since a stronger magnetic field, shouldn't the current increase. I believe the decrease in ...
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Can you be an athletic superstar just be switching a switch on your wrist? [closed]
Can you be an athletic superstar just be switching a switch on your wrist?
There are two (2) glands in your body that regulates your bodies ability to cope with stressful conditions. Each of these ...
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Electric potential with Galvanic cells vs electric potential with point/test charges?
For a positive source charge and positive test charge, the electric force will move the test charge from an area of high potential to an area of low potential. Therefore, if a negative electric ...
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A cell is connected in two kinds of circuit, one with only 1 load(a bulb) other with 2 bulbs in which case would it be used up faster and why? [closed]
Case 1- Cell is connected to 1 bulb
Case 2- Cell is connected to 2 bulbs
In which case cell would be used up faster?
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Lenz law in a stationary magnet
In this specific arrangement how do we find out the direction of current at different points of the rotation of the coil.
With a bar magnet and a coil it is fairly easy to predict the direction of ...
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2answers
65 views
Induced current in a closed loop in opposing directions
When a magnetic field is given to the loop as in the figure(sorry for the horrible drawing);
I'm told that there will be an anticlockwise current induced in both the 'inner' and 'outer' loops, ...
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Do gas-powered plants use Higher Heating Value(s) (HHV) or Lower Heating Value(s) (LHV)?
Does anyone know if natural gas power plants, and other utilities for that matter, obtain as much energy as (reasonably) possible from burning methane (or coal, or whatever)?
Where would one find that ...
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Cutting down on power by bypassing mechanical to electrical conversions: Why not? [closed]
The only answer to this I can think of is energy portability issues.
Another modern-world insanity is converting mechanical energy to electrical, only to turn it back into mechanical. The example I ...
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22 views
Is it possible to overload a thin conductive object with electrons?
A parallel-plate capacitor is a very simple device. To make one, you can take two metal plates, separate them with a dielectric material, and voilà! You have a capacitor.
Given a dielectric ...
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26 views
RMS value of Alternating values [duplicate]
What is a RMS value and what is the point of RMS value? Why do we calculate it? Please be concise and precise and kindly express it in layman terms.
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How does the electric field strength due to an arrangement of infinitely charged plates remain constant?
For a point charge, the electric field is given something as the inverse of the square of the distance from it. But, that only means that as we go farther away from the point charge, the number of ...
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Can vacuum breakdown occur from a positively charged surface?
Against a sufficiently large voltage, resistance is futile.
Although the vacuum is a very good insulator, electrical breakdown can occur even in a perfect vacuum in the presence of a very strong ...
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Experiments to show that a voltmeter measures energy per unit charge
In "Physics for the Inquiring Mind" by Eric Rogers, an experiment is described to show that a voltmeter (considered as a black box) indeed measures work done per unit charge by measuring the ...
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Voltmeters that makes a genuine measurement of force and put it into a calculation of force times distance/charge
In "Physics for the Inquiring Mind" the author Eric Rogers writes:
There are voltmeters which make a genuine measurement of force and put
it into a calculation of FORCE * DISTANCE / CHARGE, ...
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23 views
Simulating current flow in solid conductors
I am curious if there is anyways to understand how does current flow through a solid conductor, e.g. How it is distributed across the conductor. How will the current flow "curve" when you ...
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1answer
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Is Kirchoff's first law based on the probability that a current splits at a junction and goes either way?
I know that Kirchoff's law comes from the fact that charge is conserved at every junction of a circuit. But is it useful (and true) to think about this in terms of probabilities? As in, the ...
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1answer
102 views
How much energy per area or volume is the solar wind producing?
Would it be possible to erect essentially a giant loop of wire in interplanetary space to create an electric generator? If so, how much power can we get?
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Why are there no brushless motors with more than 3 phases (6, 9, etc.)?
My understanding is that adding phases will (up to a point) add the ability to push more power through a motor (more Amps total, same per individual winding wire), generating more torque for similar ...
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1answer
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Did Victor Hess discover cosmic rays directly, or muons with his gold-leaf electroscope?
Most histories just mention cosmic rays themselves, but I also read that cosmic rays themselves rarely make it far into Earth's atmosphere, and it is usually muons, (or tauons or electrons) detected ...
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How plasma ball works?
I am always confused with the concept of earthing in electricity. I have read and done few experiments and I understand that electricity needs to close the circuit. I can understand that from the ...
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Electric swatter working when it is off
When I switch on a fly swatter for some time, then turn it off and touch it with a conductive material(such as a pencil), I get a momentary spark. The spark is not continuous that I get when the ...
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1answer
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What happens to a function generator waveform when another capacitor is added in parallel with an existing capacitor in a circuit?
I am trying to gain an understanding of the first-order response of RC circuits and measurement of capacitance in a capacitive sensor using function generation and oscilloscopes. I had a question ...
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What is the importance of magnetuc flux cutting the surface of coil
Iam a bit confused about magnetic flux lines cutting a coil say if we have a rectangular coil abcd like in the dynamo and the sides ab and cd are perpendicular to the magnetic flux when the plane of ...
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1answer
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Back emf when circuit is closed and opened and the conservation of energy
Ok, this might sound like a stupid question but I am legitimately confused. Imagine a circuit connected to a solenoid. When a circuit is closed (by a switch), there will be a quick increase in current,...
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26 views
Luminance relation between LEDs when connected in series
I am reviewing a homework problem where we are given three LEDs; in the blue ($450$ nm), in the green ($550$ nm) and in the red ($650$ nm). We are told that the current efficiency $$\eta=\frac{...
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1answer
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How does cold make batteries drain faster yet simultaneously they should be refrigerated to keep a charge?
I have always known via common knowledge that batteries drain quicker when it's cold. I've been told it's best to keep them in an inner pocket close to body heat when outdoors (e.g., batteries for ...
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1answer
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In a new unconnected battery, has a chemical reaction already occurred to cause excess electrons on anode end?
REACTION 1: When I buy a new unconnected alkaline cell, has a chemical reaction already occurred on anode end which releases electrons on anode end?
REACTION 2: Also, in the same new unconnected state ...
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What is electric energy?
From what I have learned it appears that while electricity is defined as a movement of charges, electric energy, on the other hand, is a form of electromagnetic waves and it moves through empty space ...
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Ground Wire to Prevent Static Discharge
I'm part of the robotics team at my school, and we built a robot for the competition. To prevent static discharge from the chassis to the circuit, we attached a wire from the negative side of the DC ...
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1answer
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Experimental measurement of the real and the imaginary parts of the macroscopic electric permittivity
I know about the Kramers-Kronig relations in electromagnetism which relate the real and the imaginary parts of the electric permittivity but how are the real and imaginary parts of this parameter ...
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Why do metals conduct electricity faster than heat?
I have read this question:
https://physics.stackexchange.com/a/561125/132371
where cuevobat says:
You will note if you examine the tables on conductors that some metals that are good electrical ...
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2answers
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How does making the conducting wires tight help current flow?
I have read most of the times that when performing activities with electric current and its effects the wire in the circuit should be in tension. But I never got the reason behind it.
So, How does it ...
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1answer
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Will there by a voltage drop in the p-type in the diode?
Assume we have a pn diode, and we have forward bias so that we get electricity through the diode.
My question:
Will there be a voltage drop over the p type? (NOT the depletion laywer, but the rest of ...
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2answers
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When an electron moves in the valence band, does it need energy?
I am wondering what actually happens when an electron moves in the valence band. As I understand an electron needs energy to free itself from an atom. Is it so that the electron gets energy to free ...
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1answer
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A question on electric current
In my physics book the definition of current is
If a charge $∆Q$ crosses an area in time $∆t$, we define the average electric current through the area during this time as
$I=\frac{∆Q}{∆t}$. The ...
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Why does the magnetic field of a straight current carrying conductor exert force on other magnets
I've just started learning about electromagnetism, we're taught about the Fleming's left hand rule.. and how it's just Newton's third law in a way. However, I don't understand why straight current ...
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1answer
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How is energy dispersed in electrosurgery?
I'm a surgeon and I use electrosurgical units on a near daily basis. From time to time I have questions about the nuances of these tools. Today, this one came to mind...
Assume:
The bladder is filled ...
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Limiting value of electrostatic equilibrium of $n$ sided polygon
If we calculate electrostatic equilibrium points of n charges placed at vertices of the polygon, they tend to move towards the side of that polygon as n increases. Taking limit for a ring; the ring ...
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1answer
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Why is my approach to this problem about charging an uncharged capacitor with a charged capacitor wrong? [closed]
This is the above mentioned problem :
Using a battery a10 pF capacitor is charged to 50V and then the battery is removed. After
that, a second uncharged capacitor is connected to the first capacitor ...
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Does the attraction between an electron and proton start a circuit or repulsion between two electrons?
Currently learning circuits and our book states that when a battery is placed in the circuit the electrons toward the end of the circuit wire is attracted to the positive terminal of the battery ...
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Hypothetically, why can't we wrap copper wires around car axles and turn them into electromagnets to help charge the batteries? [closed]
We already have a magnetic core, why can't we use it to recharge the batteries? The only problems I see with it are potentially wiping magnetic data, but doesn't the electromagnet have to be revolving ...
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Can lightning be used as a source of energy? [duplicate]
Is it possible to use lightning or thunder as a source of energy, with the help of dielectric breakdown and splitting?
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1answer
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Why do electron holes move away from heat?
I'm currently learning about thermoelectric generators and I learned about the two p and n semiconductors. I understand how the n-type semiconductors works which is that when one side gets heated then ...
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Are the breakdown voltages of silicon dioxide and silicone dioxide the same?
Silicon dioxide has a breakdown voltage of $> 10$ MV/cm [1]. However, I am unable to find any information about the breakdown voltage of silicone dioxide. Since silicone contains oxygen (and ...
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2answers
195 views
What does applying a potential difference mean?
I have been studying the physics of accelerating electrons through a vacuum using an electron gun. It says that a potential difference (p.d.) is applied between the filament lamp and an anode. The ...
