New answers tagged electrical-resistance
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How does the thickness of a sample affect the accuracy of four-point probe resistance measurements?
No. It's NOT valid for any thickness, if your probes are applied from the top, as in the linked picture (or as is common with the four probe machines you buy, which will look like the lined picture).
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Resistor Capacitor circuits
Some notes: aluminum electrolytic capacitors have "leakage" current (tantalums less so). they are made by forcing current through which builds up the insulating oxide layer. this is called &...
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What's wrong with this solution to freshman textbook example for Ohm's law and Kirchhoff's current law?
Ok simply put, out of 13A, 3A goes down and 10A goes forward
(because current divides at nodes, imagine it like water going down a pipe division the pressure into both pipes will be same, but amount ...
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In a simple battery + resistor circuit, what form of energy is lost from the electrons upon exiting the resistor?
I was writing an answer to a very similar question that was closed and merged in this one, so excuse me if I repeat the other answers. The particularity of this other answer is that it called for an ...
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Why do lamps in circuit have potential difference but two points in cable without anything in the middle of it have no potential difference?
Suppose you have a 100W lamp on a 100V supply, like the wall supply in the US. From $P=V^2/R$, you get that the lamp has a resistance of 100 Ω.
Now you go to buy a new power cable for your lamp. The ...
rob♦
- 91.6k
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Why do lamps in circuit have potential difference but two points in cable without anything in the middle of it have no potential difference?
Unless the wire/conductor has no resistance it would have a tiny potential difference. The lamp has high resistance as it consumes the energy and converts it to heat and or light thus giving a much ...
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Why is my idea of voltage drop wrong?
Indeed, the charge carriers are accelerated because of the potential difference and hence the electric field. Potential energy is converted to kinetic energy. Due to scattering they reach an ...
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Why do lamps in circuit have potential difference but two points in cable without anything in the middle of it have no potential difference?
According to Ohm's law, the voltage drop $V$ over a component of resistance $R$ is given by
\begin{equation}
V = IR.
\end{equation}
where $I$ is the current. Since the resistance of the wire is ...
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Precise relation between temperature change and physical quantities
$$ \frac{l_1}{l_2}=\frac{1+\alpha\theta_1}{1+\alpha\theta_2} \implies
> l_2 = l_1\frac{1+\alpha\theta_2}{1+\alpha\theta_1} $$ The equations
above give us two different answers for lengths at a ...
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Accepted
Visualization of resistance
What does a resistor do in an electrical circuit?
The resistance of a conductor limits the amount of current that can flow in the conductor for a given potential difference.
I have been told to ...
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What's the difference between conduction current density and source (impressed) current density in an $RC$ circuit?
Kirchhoff's first circuital law is about currents $I$, not about current densities. Thus we have $I_i=I_c$, but it is not necessary to have $j_i = j_c$, because cross-section of the source and of the ...
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Visualization of resistance
As the other answer has pointed, there is not a direct analogy between the two situations but I would like to add that you can force-create an analogy between fluid flow in a pipe and current flow in ...
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Visualization of resistance
I have been told to think of water flowing in a pipe and which has a narrow part
I don't think the narrow pipe is a good analogy of a resistor.
In simple fluid dynamics the water in the narrow part ...
- 56.5k
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Why is my idea of voltage drop wrong?
To simplify matters, assume that the mobile charged particles under consideration are positive and ignore the thermal motion of the charged particles.
I am going to compare the motion of a charged ...
- 97.9k
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Why is my idea of voltage drop wrong?
First of all drift velocity of electron is negligible i.e. $10^{-4} \,\text{m}/\text{s}$. So the changes in it are not considered to be effective. Whereas, the voltage drop is actually energy drop in ...
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Why is my idea of voltage drop wrong?
Voltage drop means voltage loss, typically in the context of electrical current flowing through a series of resistors or a piece of resistive wire. Let's say we have a loop of resistive wire leading ...
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Why is my idea of voltage drop wrong?
AlphaPhoenix made a series of videos on this topic that are just exemplary. You should begin by watching this, and then this.
so voltage decreases along the length of the conductor, on connecting a ...
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Doubts in circuit analysis
Maybe I am loosing some detail here, but assuming that all resistances are equal, and looking at the symmetry of the circuit, all dpps and currents should be the same in module if you flip the circuit ...
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How is current affected by a charging capacitor in parallel to a resistor?
The simplified model of a battery as a constant voltage source and a capacitor as a perfect capacitance falls apart when you close a switch connecting one to the other.
The capacitor draws current ...
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How is current affected by a charging capacitor in parallel to a resistor?
Since you have defined your circuit using physical devices, and you seem to be asking a question about the same, the difficulty you are having is caused by your neglect of the resistances of the ...
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