Questions tagged [electricity]
The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
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Explain electrostatic potential and similar terms?
How would you explain
electrostatic potential,
electrostatic potential energy,
electrostatic potential difference, electrostatic potential gradient and common potential
What is the difference between ...
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1answer
29 views
How does a dielectric form in an electrolytic capacitor?
I have found that this happens through anodic oxidation, but can't seem to find how this happens. Why do some metals form an insulating layer when in contact with an electrolyte?
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Capacitance of ferroelectric capacitor in saturated regime
Consider a ferroelectric plate capacitor connected to an AC source in the presence of a strong static external electric field which sets the ferroelectric medium in the saturated regime.
The question:
...
2
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1answer
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Why Ohm’s law doesn’t work in these scenarios (inside ideal battery and in vacuum)?
Scenario 1 - Ideal battery
Suppose I have an ideal battery whose electrolyte’s resistance is zero. In the working battery there will be current flowing inside the battery also (due to battery forces) ...
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3answers
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What is the significance of direction of current density?
I studied about the direction of current density but nowhere it is mentioned that what is the significance of direction of current density
Also I want to know why we used dot product instead of cross ...
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3answers
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In metals the conductivity decreases with increasing temperature?
I am currently studying Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light, 7th edition, by Max Born and Emil Wolf. Chapter 1.1.2 Material equations ...
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About Signal Conversion [closed]
Question is weird but It's about something that I really want to try
AC power in here India has 50hz frequency, What I really want to try is to make a series path with two continuous conversions. In ...
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2answers
12 views
Is the secondary current in a transformer dependent upon the load resistance?
Is the secondary current in a transformer dependent upon the load resistance? If no, can we use a small(handheld) generator,with a step up transformer to power a house? Please give the mathematical ...
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Basic Electrification problems
I am reading the experiments about Electrification in Part I Chapter I in "A Treatise on Electricity & Magnetism". There are few experiments on Electrification by friction, induction and ...
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1answer
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Persistent confusion about “electrons” in electricity
These two statements seems contrasting:
Electrons in the outermost shell are loosely held to the nucleus.
In a metal electrons move freely in all directions.
I am very confused as to its position.
...
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3answers
56 views
Why does the power remain constant during the stepping up and stepping down of current in transformers?
I understand quite a bit of transformers, their structure and other concepts and formulas related to mutual induction. However I'm not able to explain why the electrical power has to be constant ...
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0answers
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Does increasing the electrode area of a battery increase the overpotential with the same current density?
I made a battery with an electrode area of 25 cm^2 and charged it at a current of 125 mA - giving a current density of 5 mA/cm^2.
I made an identical battery but much larger electrode area - 350 cm^2 ...
34
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8answers
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Is electricity really the flow of electrons or is it more involved?
I am new to the physics category of the Stack Exchange site. I apologize if my question is wrong, too broad, simple, or worded incorrectly. I am just trying to figure out what is true and false when ...
2
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1answer
24 views
in photoelectric effect, where do electrons go when they are ejected from metal?
When light shines on a metal, electrons are ejected from the surface of the metal provided the energy of the photons are greater than the work function of the metal.
My question is, (1) where do the ...
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1answer
18 views
It there any difference to releasing the water in the air or water layer when producing hydro? [closed]
When I look at hydro power plants it looks like they release the water in the water level. That is, below water. It there any difference to releasing the water in the air layer and water layer when ...
2
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0answers
25 views
Problem with ideal conductors [duplicate]
Let's assume we apply a potential difference or a battery accros an ideal conductor.Now as electric field across an conductor is zero potential from any end of the battery will never drop this is what ...
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1answer
28 views
What is the exact formula to use to find the resistance of a wire as it varies with temperature [closed]
The numerical to which I am referring has a given link. Please check:
https://www.toppr.com/ask/question/the-temperature-coefficient-of-resistance-of-a-wire-is-000125-per-degree-celcius-at-300k/
Do we ...
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1answer
36 views
Does the electron in wire too move because of voltage difference?
When we talk about electricity through a circuit because of a battery it is said that the electrons from negative terminal travel to positive terminal of the battery.
I can't help but imagine about ...
4
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1answer
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What does the term 'high voltage' really mean?
This might be a dumb question but i am not so familiar with the word voltage:
What does the textbooks really mean when they say high voltage?. Does that mean:
There are more charges so more voltage, ...
3
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3answers
43 views
Is there an expression for resistance in a circuit derived from Coulomb's Law?
Coulomb's Law states that the repelling force felt by two charges is proportional to the magnitude of their charges and inversely proportional to the square of the distance between them.
Defining ...
7
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4answers
653 views
What's the point of an RMS value? [duplicate]
the RMS (root mean square) value of $f(x)$ is defined as:
$$f(x)_{rms}=\sqrt{\frac{\int^b_a (f(x))^2dx}{b-a}}$$
Why do we do this very specific thing of taking the square, the mean, and then the ...
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1answer
37 views
At what speed does electric information go?
Note: If a better title can be made, pls do so.
Consider a parallel circuit with each branch of equal resistance. If you increase the resistance of the further branch, how long would it take to detect ...
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2answers
44 views
Why doesn't electric potential decrease gradually across a wire?
Let's assume that the resistance of a wire is zero. Now, suppose the wire has a length of 10 m and is connected to a battery with an emf of 10 V. According to my physics textbook, the electric field ...
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1answer
21 views
Is the path of an electron between successive collisions (with positive ions of the metal)a straight line in the presence of electric field?
I feel that the answer should be yes. While the entire journey isn't straight, the journey between successive collisions is straight. But the internet and my book says the opposite (the path is curved)...
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1answer
34 views
Current flow in potentiometers
In the following circuit involving a potentiometer;
Assume $V$ to be the voltage produced by the cell in the primary circuit across the length $AJ$ of the potentiometer wire, and $E$ to be that ...
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Electric Field Penetration through Multi-Layer Sandwiched Plates
I'm trying to understand how the total electric field changes as it passes through layers with different electrical permittivities and conductivities (as shown in the attached figure). The rectangular ...
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0answers
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Formal definition of charge density and current sources in classical electromagnetism
Charge density and current sources are fundamental to classical electromagnetism and appear in Maxwell's equations and everything that comes after. They are intuitive, charge density is a scalar field ...
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1answer
35 views
How can opposite charges neutralize so fast?
I saw that the two end wires of a capacitor when touched to each other neutralizes quite fast(as the flash after their contact was there only for a second), how can charges neutralize the capacitor so ...
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2answers
41 views
Why do electrodes have to touch initially in order to establish an arc?
In order to establish an arc in a low voltage, high current suruation such as welding, why do the wires or electrodes need to touch, then pull away to establish an arc?
Why would this arc not be ...
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4answers
104 views
Why exactly do we feel a shock when we place our hand into a conducting solution?
I have a very naive question.
Suppose you have pure water in a flask, and you place two ends of a copper wire (which are connected to a battery) into the water.
If you were to place your hand into the ...
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1answer
12 views
Charge distribution and electric field on a conductive sheet
I have a sheet of paper, clad with a half-circle shape of conductive material. The half circle is not filled to the center. The inner radius is about 8cm, and the outer radius about 12cm, not that the ...
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1answer
26 views
How much energy do I need to charge an electric car? [closed]
Suppose I have an electric car with a battery capacity of N kWh, how many kWh of power do I need to recharge it? It can't be a precise match of N - some must be lost through heat, powering the ...
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1answer
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What does the voltage across a resitor tell you, and why does a voltmeter provide the voltage it does across multiple resistors in series?
In my physics class, we have begun talking about potential difference, charge, resistance etc. While watching online videos for extra help on some clarification, I often hear that as electrons move ...
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1answer
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Explanations for different current values inside a battery
I was just learning about what happens to current inside a battery, and my professor gave an example: Let's say we have a $1$ volt battery connected to a $1 \Omega$ load. Then he claimed that the ...
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1answer
28 views
Does electromagnet work without heat of wire?
If we isolate wire with thin wire and assuming that no heat rejected by wire then does electromagnet work. If it work then it violate conservation of energy .
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0answers
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Is there any relation between the torque required to rotate shaft of the alternator and the load connected to it?
Suppose that a TV and a LED bulb both could be operated by the electricity generated by the alternator. In the initial phase the LED bulb is connected to the alternator and then it is replaced by the ...
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1answer
28 views
Difference between heat emited from resistor and power on the resistor emited to heat
Consider a simple electric circuit.
I just not understand what is the difference between heat emited from resistor and power that is on the resistor that emited to heat
why one is $p=I^2R$
and the ...
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0answers
14 views
Electric motor magnetic moment
Suppose I know that an electric motor winding produces 200 Nm torque in 0.2 T magnetic induction field. Is it possible to calculate the rotational magnetic moment produced by that motor winding just ...
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2answers
41 views
Is it possible to accelerate the air electrically?
Is it possible to accelerate the air electrically?
There are other techniques such as, for example, compressors where the air can reach supersonic speeds. But is it possible to accelerate air to ...
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1answer
19 views
Decreasing of number of electrons in direction opposite to current [closed]
When a current is established in a wire,the free electrons drift in the direction opposite to the current.does the free electrons in the wire continuously decrease?
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1answer
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What will be the variation in potential in a zero resistance wire connected to a battery? [duplicate]
Consider an electric circuit with a battery and a resistor connected through a wire of zero resistance. Since the wire offers no resistance, all points on the wire are at same potential, then why on ...
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6answers
378 views
How do capacitor plates maintain equal but opposite charges in a circuit?
I have a question regarding capacitors and their charge neutrality. When capacitors are used in circuits, the assumption is often made that the plates of the capacitors have equal and opposite charges....
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0answers
24 views
What causes the charges in conductor to move towards lower potential terminal of cell [duplicate]
Whenever a conductor is connected to a cell,what causes the conventional positivecharges inside it to move towards the lower potential level of cell..
My question is whether the charges experience a ...
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0answers
21 views
How does Cell mechanism transfer charges against potential difference
In case of a cell,the positive charges (conventionally)move from Higher potential to lower potential..but how actually it happens when charges reach to lower potential terminal of cell ,whether cell ...
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1answer
37 views
Any machines that use currents in nanoampere? [closed]
Milliampere and microampere is quiet common in human-made machines, are there examples of machines that use nanoampere currents?
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2answers
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How does current flow when all the electrons are already moved to neutralize the external charge given?
My textbook says the following:
Suppose we put $+Q$ and $-Q$ charges at the two ends of a copper wire. The electrons will be accelerated due to an electric field towards $+Q$. They will thus ...
3
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4answers
204 views
How much current will go through my body if I were to put my finger in an outlet?
i know this is a silly question, but i couldn't manage to wrap my head around it. I am kinda new to electronics.
My home's outlets provide 220V. Upon doing some (a lot) research, the current that ...
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2answers
24 views
If power consumed in a resistor is equal to the power supplied by the the source, then why doesn't the flow of charges stop?
So the energy given to the charge (assume it to be positive) in unit time is completely consumed when it crosses the resistor, why does the charge still flows towards the battery.
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What exactly is the framework (or model) in which Electromotive Force is a meaningful quantity?
As far as I understand, there are two definitions of "Electromotive Force", one being the integral of a non-conservative (non-dissipative) force per unit charge acting on electrons along a path in a ...
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1answer
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Potential difference across a wire [duplicate]
Why potential difference across no resistance wire is same across two points.
