Questions tagged [electricity]
The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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If photons are the carriers of the electromagnetic force, why isn't electricity made of photons?
If photons are the carriers of the electromagnetic force, why isn't electricity made of photons?
Or, why isn't every electromagnetic effect described in terms of photons, if they are the ones carrying ...
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Working principle of Van de Graaff generator revisited
I have a few questions about principle how van de Graaff generator works. To avoid confusion I will use numbering from the wiki picture:
[ADDED LATER #1] See also here for nearly identical ...
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How to make capacitive stylus for smartphone displays that work by itself (insulated from the arm)? [closed]
https://en.wikipedia.org/wiki/Stylus_(computing)
Capacitive styluses are made of a conductive material (typically as a metal rod or barrel) to transmit electrical charge between the hand and a rubber[...
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Is it possible to generate electricity from muons instead of photons?
I understand that solar panels generate electricity by converting photons from sunlight. This made me wonder whether it would be possible to use other types of cosmic radiation, such as muons, to ...
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Why does my electroscope not work after the first time?
I have a gold leaf electroscope which works very well the first time. After thus it stopped working.
Even when the gold leaf moves, it moves very less. How to fix this?
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Touching a conductor carrying eddy current
When we touch a conductor with eddy current flowing on it, will we get a shock?
Because in my opinion there's an induced EMF due to which eddy current flows (assume the conductor is in the region ...
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Semiconductors and holes
Hello I am a 12th grade student preparing for Jee and just started learning about semiconductors, I wanted to ask that in pure silicon semiconductors, when a electron is released and goes into the ...
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Could lightning occur in fog or mist?
In the article What's the Difference Between Fog and Clouds? it says:
Clouds and fog both form when water vapor condenses or freezes to form tiny droplets or crystals in the air, but clouds can form ...
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Charge as an intrinsic property of matter [duplicate]
Is charge an intrinsic property of matter? For example, I can induce a static charge and also we see ions which are charged. But from a fundamental aspect, is it an intrinsic property of a substance?
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How is the "energy" given to electrons by a battery? [duplicate]
Studying electricity, we come across the ideas of voltage and current. Current is fairly simple to understand as its simply the rate of flow of charges in unit time. However, the cause for this ...
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If the field is directed from lower potential to higher then the direction of electric field [closed]
If the field is directed from lower potential to higher then the direction of electric field is taken to be positive or negative there is a lot of confusion, the famous unacademic site on google ...
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How does charging by rubbing/friction occur? [duplicate]
Electrostatics
Knowledge of insulators and work function
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Could you charge a battery using with a long radio aerial?
I was remembering how as a child I powered a Crystal Radio by just running a long wire 3 or 4 times around my room architraves/cornices. And was wondering why the same principle couldn't be used to ...
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Measuring electrical fields from mains - difference through near grounding conductor
I often notice that the electrical fields in my home created by mains differ in dependence how close the grounding conductor is to the measurement antenna.
I haven't managed to model this yet, so I ...
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Eddy current levitating force?
Hi,
Is it convenient to ask the following question about eddy current levitating coil?
Suppose the rms value of ac sinewave current current in the
coil/solenoid is kept constant ,
but the frequency is ...
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Why are electric 'sparks' bright?
My understanding of sparks are that they're produced by discharge of electric charge due to accumulation of a large number of electrons in a region and due to a high potential difference compared to ...
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Does Faraday Cage also work in a changing electric field?
My question comes from a example in my textbook (see the photo). It illustrates a Linear Accelerator used to accelerate electronics. The voltage between the metal "tubes" will change ...
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Did Charles P. Steinmetz argue that an electric field always has both dielectric and magnetic components, and that both reside outside the conductor?
In the early 1900's, Charles Proteus Steinmetz was a leading authority on electricity and wrote many books explaining its principles.
In his book titled "Electric Discharges,Waves And Impulses&...
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Doubt in Ampere's circuital law
Suppose there is a current carrying conductor of finite length, if we apply biot-savart law for a point in the midplane of the conductor we can integrate for the magnetic field.
The result from the ...
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Weird behavior in spark gap alpha particle detector
I recently happened upon some americium. I wanted to measure its alpha emissions, so I built a spark alpha detector which consisted of some thin copper wire stretched about five millimeters above a ...
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Charge within an inhomogeneous current carrying conductor?
There is a simple proof that in steady state, there can be no net charge density in the interior of a homogeneous conductor carrying a homogeneous current.
We need the continuity equation
$$\nabla \...
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Why does a separation of charges create a potential difference?
I am in class 12th and was reading about electrode potential in electrochemistry. While explaining it, my teacher said that due to the concentration of electrons in the anode and positive ions in the ...
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Why does the LED glow brighter?
So yesterday I was doing a physics demonstration using a plasma ball in which I showed the students that we can light up a small led by holding one of it's end with our fingers and bringing the other ...
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How can we justify, in principle and without using any formula, that resistance decreases when area increases? [closed]
Here’s my reasoning:
Think of a tube filled with water. If we push water using a piston, the pressure is F/A. Keeping the length fixed, increasing the area reduces the pressure, so flow becomes easier....
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On a Wimshurst electrostatic machine, why use "combs" instead of brushes?
The Whimshurst machine is an electrostatic generator that uses "combs" to collect charges from passing "sectors" (charged plates) into leyden jars.
On the picture both the comb (...
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Can electricity flow through the disconnected circuit? [closed]
If we have a circuit that is 1 light minute long, with a bulb located in the middle (meaning 30 light seconds from each end), and we disconnect the circuit (separating the two ends with a dielectric) ...
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How does the length of a current carrying wire affect the induced magnetic field?
We want to measure the magnetic field around a current carrying non-ideal finite wire made of ohmic material. In other words, the wire has some resistivity $\rho$ and it has constant cross sectional ...
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Why does the direction of current reverse in an AC generator but not in a DC generator—mechanically speaking?
I understand that in an AC generator, the current reverses direction periodically, while in a DC generator, the current flows in a single direction. This difference is usually attributed to the type ...
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Does increasing resistance increase the brightness of a bulb and the heating effect of Nichrome?
In our homes we have parallel connection. So $V$ is same. Hence for power we must use $P = V^2/R$ but this means that increasing resistance will cause less power and so less energy per unit time is ...
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Ohm's law interpretation correction
Ohm's law states as follows:
current $(I)$ through a conductor between two points is directly
proportional to the voltage $(V)$ across the two points, and inversely
proportional to the resistance $(R)...
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Is it necessary for the electric field to be constant throughout the length of a conductor for the steady flow of current?
Is it necessary for the electric field to be constant throughout the length of a conductor (not necessarily of uniform cross section) for the steady flow of current?
While deriving the expression for ...
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Why Must Electric Current Flow in Closed Loops, Even When Connected to Ground? [closed]
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In any electrical circuit, it is commonly stated that electric current must flow in a closed loop, starting at the positive terminal of a source and returning to its negative terminal. ...
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Linking the voltage supplied to a dc motor with the lift produced by a propeller connected to it [closed]
I have a regular DC motor connected to a power supply that can reliably provide a specific voltage to a DC motor that I have connected to a propeller. I wanted to see how the lift produced by the DC ...
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What's the difference between arcs that can melt metal and arcs that are thin and simply just feel like they pinch you?
There are 2 different arcs I've seen online, the ones that look like a thin line that you can put your hands in and only feel a pinch, and ones strong enough to melt metal (as shown below). What makes ...
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What is "Induced Atmospheric Vibration"?
The blackout seen today on the Iberian Peninsula has been attributed to a "rare" phenomenon known as "induced atmospheric vibration":
It says that "due to extreme temperature ...
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Why do we take the RMS when talking about the effective voltage of AC instead of taking the mean of $|V(x)|$?
When we talk about the effective voltage of AC, we take the Root-Mean-Square, which ends up being $V_{peak} / \sqrt{2}$ for sine wave energy supplies.
Why do we not just take the average value of the ...
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Can distilled water conduct electricity this way?
Imagine there is a glass container with a low water level (so that sunlight doesn't lose too much energy when it gets to the bottom of the container).
Suppose the water is distilled (pure $H_{2}O$). ...
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Multimeter cannot read the capacitance
I am making a DIY Paralel Plate Capacitor with the dimension of 27.5cm times 4cm seperated by 80 gsm paper. Assuming paper thickness is 0.1mm I should get around 3.6nF.
But when I test using my cheap ...
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How do the electrodes in an electrolytic circuit get their respective charges?
I don't understand how the electrodes get their respective charges. I have read somewhere that electrons are pulled from the anode to continue the current, so it makes sense why it is positively ...
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How to calculate temperature, considering heat lose, when heat up a conductor by current?
Consider a copper tube, that weights 1kg, surrounded by water. Current $I$ flows through this tube with total resistance $R$.
I want to know what temperature will copper tube be after time $t$.
...
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If a conducting wire touches one side of a charged capacitor, will the wire get excess charge?
Let say I have a charged capacitor.
Then I use a conducting wire to touch and take away from the positive terminal. Will the wire have excess charge?
If the wire has excess charge, how will the ...
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Why do rural power lines sing at various pitches?
This didn't help: Why do power lines buzz?, as what I'm hearing is not a buzz like a transformer.
Observations:
It occurs on both calm days and windy days.
It does not always occur. I suspect it's ...
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Is it possible to create a small instance of a sprite?
Im a high school student hence have no experience,the phenomenon im asking about is TLE (Trans luminous Events) specifically a sprite. From what i know, sprites are formed due to excitation of ...
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Does the anomalous skin effect lead to increased noise at high frequencies?
I was recently reading about the anomalous skin effect, wherein the models governing the skin effect behaviour break down as the frequency gets high enough for the skin depth to approach or fall below ...
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Thomson's Electron Experiment
I was looking over Thomson's cathode ray experiment. I am wondering why the cathode ray itself was insufficient to determine that the ray was composed of negatively charged particles. If you connected ...
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In a circuit of only a capacitor and an AC voltage source, why does the capacitive reactance function as a constant resistance?
Forgive me if this is a silly question.
Consider a circuit of an AC power source and a capacitor. The capacitor will oppose current flow as it charges due to accumulated charges on its surfaces; this ...
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Speed of electric arcs
How fast, roughly, are electric arcs like those from a tesla coil or jacob's ladder travelling through the air? Are they anywhere near as fast as lightning?
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Most efficient shape for a capacitor
A conducting system consisting of a conductor shell B and A in its cavity is considered as a capacitor in this question. Any capacitor whose shells extend indefinitely can be considered too(e.g. a ...
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Behaviour of a capacitor connected to an AC source when it's just switched on
So typically we only analyze the behaviour of a capacitance at steady state when the capacitor has achieved a stable charge-discharge cycle but what about when we just connect it to the AC source.
I ...
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Is the relaxation time defined at an instant of time or for an time interval?
Say we are given a conductor or system which is not in steady state conditions, that is the drift velocity, electric field etc all vary with time and location of that conductor
Now, say we are to find ...
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