The resistors tag has no wiki summary.
24
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2answers
9k views
On this infinite grid of resistors, what's the equivalent resistance?
I searched and couldn't find it on the site, so here it is (quoted to the letter):
On this infinite grid of ideal one-ohm resistors, what's the equivalent resistance between the two marked nodes?
...
12
votes
2answers
1k views
The “Nerd Sniping” problem. Generalizations?
This question is motivated by this xkcd comic strip
.
The problem is indeed interesting, and my first recollection upon reading this was a similar problem in the book Problems in General Physics by ...
10
votes
3answers
1k views
Is it possible to mathematically derive the formula for resistance?
Resistance is given by $\rho L/A$, where $\rho$ is the material constant, $L$ is the length, and $A$ is the area.
Is there any way that this can be derived mathematically, or is the only way ...
7
votes
9answers
757 views
I don't understand what we really mean by voltage drop
This post is my best effort to seek assistance on a topic which is quite vague to me, so that I am struggling to formulate my questions. I hope that someone will be able to figure out what it is I'm ...
7
votes
1answer
351 views
Resistance between two points in an infinite metal sphere/cube
Let's imagine that we have a tridimensional metal object of infinite size, and decide to calculate the resistance between two arbitrary points. How would we go about doing this?
I have thought of two ...
5
votes
4answers
2k views
Resistor circuit that isn't parallel or series
What's the equivalent resistance in this circuit (between points A and B)?
5
votes
2answers
1k views
how calculate resistance between two points for arbitrary resistor grid?
I need to calculate resistance in an electrical grid.
Grid is a graph. Edges of a graph are resistors. How calculate resistance between any two vertexes for arbitrary graph?
I know Kirchoff law and ...
5
votes
2answers
168 views
Modeling stochastic process with frequency-dependent power spectrum
I'm trying to model of Johnson-Nyquist noise propagation in a nonlinear circuit. An ideal (linear) resistor can be modeled very nicely by the Fokker-Planck equation (equivalently, the drift-diffusion ...
5
votes
1answer
537 views
How does spring constant change with resistivity changes
I want to create a set of silicon based materials that have been doped with different materials and/or different amounts of dopants. The purpose of this is to see how the spring constant of silicon ...
4
votes
5answers
3k views
What would be the effective resistance of the ladder of resistors having n steps
I'm a tutor. This is a high school level problem. In high school, every one have might have solved a problem of effective resistance of a ladder of resistors having infinite steps. Now the problem is ...
4
votes
2answers
46 views
Equivalent RC circuit to a RRC circuit?
I'm in doubt about a situation that I've seen sometimes: imagine we have a resistor in parallel with a resistor and a capacitor in series. Since I don't know how to generate figures of circuits to ...
4
votes
2answers
715 views
Wheatstone bridge galvanometer error
We had to measure the resistance of $R_x$, we balanced the Wheatstone bridge and did calculations. My question is: we didn't include galvanometer error into calculations. Why is that? I read that it's ...
3
votes
1answer
374 views
General integral to find resistance
My question is: is there a simple and truly general equation for the resistance between two electrical equipotential surfaces?. Obviously, if so, what is it, and if not, why? It would be very ...
3
votes
2answers
304 views
The role of resistor in e.g. an AND gate
What is the role of the resistor in e.g. an AND gate like this one? :
One often sees lots of resistors in electric circuits, but I haven't really understood their role.
2
votes
3answers
2k views
Wheatstone Bridge
Why is using a Wheatstone bridge such an accurate way of calculating an unknown resistance? What are the benefits of using it over Ohm's law?
It seems that it has something to do with the wires ...
2
votes
2answers
184 views
Is equivalent resistance always lower if we add a resistor to a passive electronic circuit?
How to prove that equivalent resistance of any passive network is always lower if we add a resistor between arbitrary two nodes?
Note that this is not necessarily a parallel circuit, 2 nodes that we ...
2
votes
1answer
148 views
What electric potential is found over individual resistors connected in series to an AC power supply?
Given a set of resistors connected in series to an AC power supply:
What formula governs the peak-to-peak voltage which will be measured when voltage is probed over individual resistors and sets of ...
2
votes
2answers
568 views
Ohmic and Non-Ohmic devices
Why do some conductors follow Ohm's law and some do not? Isn't there any universal law that can explain the flow of current?
2
votes
1answer
350 views
Effective resistance of inductor
In a lab experiment, we connected a simple circuit: an AC voltage source, connected (in series) to a variable resistor and an inductor. We measured the current in the circuit, and the voltage that ...
2
votes
1answer
64 views
Is Joule heating only between charged particles?
The Wikipedia page for Joule heating explains
"It is now known that Joule heating is caused by interactions between the moving particles that form the current (usually, but not always, electrons) and ...
2
votes
4answers
812 views
Total Resistance of Infinite Resistor Grid?
The problem of the infinite resistor grid is very common. The solution for the resistance between any 2 nodes in an infinite resistor lattice is all over the internet.
My question is somewhat similar ...
1
vote
5answers
568 views
Parallel circuits - Overall resistance decreases with additional resistor
Let's say that there is a parallel circuit with two identical resistors in parallel with each other. If a third resistor, identical to the other two, is added in parallel with the first two, the ...
1
vote
3answers
105 views
Why is current not 0 in a regular resistor - battery circuit immediately after you closed a circuit?
In regular open circuits with either a capacitor or inductor element, (when capacitor is uncharged) with a battery, when a switch is closed to complete the circuit the current is said to be 0 because ...
1
vote
2answers
171 views
Fundamentality of voltage to current
From Ohm's Law :
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points.
I would like to know if ...
1
vote
3answers
150 views
How exactly does a resistance reduce current?
I've heard that resistors are used to decrease current to a particular appliance, such as in the regulator of a fan. However, I've also heard that the total current in a circuit is always the same- in ...
1
vote
3answers
2k views
Finding current using EMF & internal resistance
What exactly is the difference between internal resistance and resistance?
This came up in the context of a homework problem I have been given:
The circuit shown in the figure contains two ...
1
vote
1answer
1k views
What defines the brightness of a bulb?
So I have a question. There are three identical bulbs, 2 of them are connected in parallel and the third is basically in series, on the same circuit. If the one of the lamps in parallel breaks, what ...
1
vote
1answer
2k views
Current against the inverse of resistance graph, $I = V/R +c$
If I have a plot of current ($y$ axis) against 1/Resistance ($x$ axis).
The circuit it is measured from is a simply 2 resistors connected in parallel to battery, where the potential across the ...
1
vote
1answer
103 views
Calculate Capacitance in Series AC Circuits?
I'm supposed to calculate the capacitance of an unknown capacitor in series, but I'm not sure exactly which equation to use.
I know the voltage across the resistor (Vr), voltage across the capacitor ...
1
vote
2answers
744 views
Physical interpretation of y-intercept in a Current vs Voltage graph
So I collected current and voltage data from a simple circuit with a power source and a resistor, using a multimeter. I created a graph for this data using excel and got the y-intercept (which is ...
1
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1answer
223 views
Resistance of Light Dependent Resistor (LDR)
Is there a mathematical expression relating the resistance of Light Dependent Resistor (LDR) with light intensity?
1
vote
2answers
760 views
Measuring the Electromotive Force and Internal Resistance of a Battery?
Here is a problem that emerged some time ago:
We needed to measure the emf(electromotive force) and internal resistance of a car battery. The only instruments were voltmeter and ammeter.
...
1
vote
3answers
165 views
kirchhoff's law.Simple question [closed]
So far I calculated total resistance and it is 4.66 ohms and there is 12 volt voltage across them, what is the best way or HOW to calculate current for each resistor ?
1
vote
2answers
711 views
Basic questions about voltage drop in DC circuit
I understand all the concepts of what voltage is using all the analogies but some things related to the drop of voltage across a circuit confuses me.
If I had a short circuit and attached a ...
1
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1answer
304 views
Non-conservative Electric Field
I was watching this video from Walter Lewin and while watching these two videos, I noticed there is a "contradiction" in what he is doing. All links direct you exactly to where he begins, so you don't ...
1
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3answers
544 views
Why does the potential drop across a battery and resistor equal the emf of the battery?
In this diagram you can see the potential difference across the battery and resistor is the same as the pd created by the battery (the battery and resistor are representing a battery with internal ...
0
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2answers
334 views
How can I measure the conductivity of a copper rod?
I would like to perform an experiment to measure the conductivity of a copper rod. What device can I use to perform to experiment? is there such a thing as a conductivity meter? All i found was an ...
0
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1answer
474 views
Relationship between resistance and voltage drop
In a series or parallel circuit, if two bulbs have the same resistance, do they have the same voltage drops? The problem I am asking about is below. Do A, B, and C have the same voltage drops since ...
0
votes
1answer
156 views
Waveforms for a given ideal inverters circuit
I have the following circuit. All the inverters are ideal CMOS.
I need to draw the waveforms for each point (A, B, D, E, Vo), given that waveform at input.
What I want to ask is if what I did so ...
0
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2answers
1k views
RC circuit theory and voltage in the capacitor vs Ohm's Law
Consider a simple series RC circuit at steady state (capacitor is full).
I've been told that once the capacitor is full we can literally "cut" the circuit because no current can flow.
That ...
0
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1answer
17 views
Confused on Calculating Resistance Distance Matrix
I am trying to create a computer program to compute the equivalent resistance over any points on any rectangular set of resistors (all with a resistance of 1 ohm). It seems that the resistance ...
0
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1answer
106 views
Cable TV version of infinite ladder network [closed]
This is a problem in a college physics textbook, and its bugging me that I can't get it.
The figure shows a circuit model for the transmission of an electrical signal, such as cable TV, to a large ...
0
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1answer
152 views
How do I solve the current of this resistor using Maxwell's Current Theorem?
I've been trying to solve this using the method the prof. taught us, and I happen to know the answer but I can't reach it no matter how many times I've tried. The circuit in question is below:
I am ...
0
votes
2answers
282 views
Voltage and resistance in series connection
In a series connection with n elements it is true that (voltage):
$$V = V_1 + V_2 + ... +V_n$$
and (resistance):
$$R = R_1 + R_2 + ... +R_n$$
If I know one of these I can infer the other. But is ...
0
votes
2answers
969 views
Internal resistance V=IR circuit question [closed]
I don't know how to resolve this problem.
A complete circuit consists of a 18,0 V battery (internal resistance r) and a resistor R. The terminal voltage of the circuit is 15,8 V and the current is ...
0
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0answers
19 views
Calculate the electric current in the given circuit when (a) Key K is open [closed]
Calculate the electric current in the given circuit when (a) Key K is open.
(b) Key K is closed.
!]each resistors of 6 ohm 1
0
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1answer
65 views
Is this series or parallel? [closed]
How do you find I? and please explain which resistors are in parallel and which are in series? ("M" and ">" are resistors)
...
0
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2answers
264 views
Capacitors and resistor in series and in parallel [closed]
In this circuit, are $R_1$ and $C_1$ in parallel and $C_2$ and $R_2$ in series?
I have think that the currents that flows trought $R_1$ isn't the same that flows trought $C_1$ so, $R_1$ and $C_1$ ...
0
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0answers
19 views
Carbon resistor [closed]
a carbon resistor is used as a thermometer on a water day when the temperature is 10 degree Celsius the resistance of the carbon resistor is 270 ohms what is the temperature on a spring day when the ...
0
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1answer
60 views
how to find the diameter of this fuse? [closed]
A fuse blows if the current exceeds 1.0 A. It is made of material that melts at a current density
of 620A/cm2. What is the diameter of the wire, assumed to have a circular profile, in the
fuse?
