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Questions tagged [resistance]

A measure of how much a conductor opposes current flowing through it. It can also refer to a part of a circuit, which has a non-negligible resistance value.

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83 views

Calculate sheet resistance in finite element method

I have a simulation with several polygonial mesh cells (Voronoi-mesh) and their centers of gravity \$P_i\$, each with its own electrical potential. Every cell has the same height \$h\$ all over. How ...
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3answers
159 views

How can I realize this nonlinear resistor?

I want to know if it's possible to realize a circuit described by the equation $$I = \sin(w V)$$ where \$I\$ is the current, \$V\$ the potential and \$w\$ a variable which characterizes the single ...
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2answers
1k views

Equivalent circuit to use when calculating the impedance of an electrical cable from its datasheet parameters

I'm trying to work out the impedance of a cable (specifically a single twisted pair of Lapp Kabel 0035836). The datasheet quotes the following information: ...
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2answers
121 views

Difference between using large vs small test resistance to check internal DMM/SCOPE resistance

For my intro lab to my Analog Electric Circuits class, one of the analysis questions is to calculate the internal resistances of the digital voltmeter and the oscilloscope, using the equation The ...
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1answer
279 views

Admittance calculation of a circuit

I am measuring the admittance of a circuit, by switching a load off and on at different loads. The admittance value I got from the measured voltage drop and current flowing through my circuit. The ...
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1answer
966 views

Power produced and internal resistance of solar cell vs distance from light source

Solar cell can be modeled (rudimentally) as a DC voltage generator \$Vp\$ with internal resistance \$Rp\$. Consider a solar cell at a distance \$d\$ from a (constant) light source. What kind of ...
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0answers
748 views

Why does a multimeter in resistance mode show initial continuity over a diode?

I originally phrased this question very differently; the original text is retained below in case background information is useful to clarify the context. When I using this digital multimeter to ...
2
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1answer
169 views

What's the equivalent resistance of this circuit?

I am a student in 10th grade and our teacher gave us this schematic to work with (Remade with circuit lab): simulate this circuit – Schematic created using CircuitLab He asked us to find the ...
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28 views

lm35 Temperature Reading increasing with Hot-melt adhesive (Calculations check needed?)

I have one question with this topic: lm35 Temperature Readings are not right after sealing with Hot-melt adhesive (How mush has it Soldering max Temp toleration ?) it answered by this (Thanks from @...
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58 views

Problem calculating fuses

I am calculating a fuse and I'm having a bit of trouble. I have a 12v 2A power supply that I want to protect, so my first thought was to place a fast 250v 2.5A fuse in series so it should blow if a ...
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1answer
53 views

Effective resistance of a NMOS

How do we calculate effective resistance of a NMOS, operating in linear region across drain and source?
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1answer
66 views

Admittance, Conductance, Susceptance definition

Admittance is the reciprocal of impedance. But: 1) Susceptance is the reciprocal of reactance, or the imaginary part of admittance ? 2) Conductance is the reciprocal of resistance, or the real part ...
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51 views

Calculating equivalent resistance using loop analysis with no applied voltage

I have a bridge circuit that I am supposed to find an equivalent resistance between points K and P for using loop analysis. I am aware that a delta Y transformation is the much more direct route, ...
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0answers
70 views

Finding equivalent capacitance and resistance from DC circuit with combinations of R and C

In order to get the simplest RC circuit and get equivalent circuit tau: How can be its transient studied if before t = 0 there only exists one resistive part of circuit? I's obvious that before t = ...
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1answer
54 views

How to find current through series of potentiometers, and if it is safe for potentiometers? (Arduino)

I have 9 potentiometer with the specs: 10k Ohms and 0.5W I'm using an Arduino Mega, and using it's 5V port output to power these potentiometers in series, and I saw online that the max current this ...
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0answers
95 views

Electric heating for glass melting furnace

Some furnaces use electricity for glass melting. Low voltage and high amperage power is passed through the molten glass through 2 molybednum electrodes dipped into the glass. The molten glass acts as ...
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1answer
64 views

How do I calculate total resistance?

As far as I understand, two resistors are connected in parallel if the node at both ends of both resistors are the same. And in series if only one node is the same. But what if between two resistors ...
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50 views

Measuring resistance of switched load

I am in the process of designing a custom vaporizer. So the main coil with a resistance ranging from 0.2 Ω to 2 Ω is switched using a MOSFET shown in the circuit diagram below. ...
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0answers
35 views

Evaluating the equivalent resistance

simulate this circuit – Schematic created using CircuitLab I want to evaluate the equivalent resistance. For that, I noticed R1, R2 and R3 are parallel connected resistors, which yields $$\...
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1answer
101 views

Y-Δ transform proof using superposition

In the Wikipedia page and in every book they prove the transformation by equaling the equivalent resistance between any pair of terminals while disconnecting the other node. https://en.wikipedia.org/...
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2answers
129 views

Eliminating the resistance variable in the total resistance/reactance equation of a series RLC circuit

Assuming that we have a simplified equation from a simple series RLC circuit where the total resistance/reactance in the series RLC circuit is equal to 100 times the resistance R: How do we modify ...
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765 views

How to make a open-circuit cable fault detector?

There are projects like this one over here: Underground Cable Fault Distance Finder, which checks if a given line is short-ciruited with any of the other lines. The location of the fault is also ...
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1answer
149 views

Can an inductive load mess up an ohmmeter's reading

I've found a something quite odd with measuring the resistance of a 36uH inductive load (see this earlier question). I can measure the resistance, which is quite low, but then disconnect the probe and ...
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2k views

Finding Values of Rd and Rs to satisfy the N-MOSFET design

I've been stuck on this design problem for a while and I am just filled with a lot of equations and unknowns and not getting anywhere with it. Here's a picture of the problem with the problem ...
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76 views

fuse metal alloy with high springiness?

Is there a fuse alloy that would have the same springiness as this except with a little wire that comes out and that plugs into something, so that it could be machined and pressed from one single ...
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0answers
214 views

High resistance (100Mohm) control using constant voltage or current source

I want to control resistance (100Mohm) programmatically. I found on this site that photoFET can solve this issue by sourcing constant current. From my understanding FET can give resistance control ...
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116 views

Analyse data discrepancies: Efficiency of wire vs current

Please help me explain why the efficiency of the wire does not follow a distinct path (ie R^2 value is low). Graph 1 Efficiency of wire vs current: http://postimg.org/image/p49bzm4ab/ Is is to do ...
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82 views

How do construct a electrical resistance tomography apparatus

Im interested in constructing an electrical resistive tomography setup to image underground structures. While I somewhat understand the principle, I have found limited information on design and ...
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1answer
2k views

resistance measurement problem with digital multimeter

I accidentally caused a short circuit with DMM common lead while measuring 220 AC voltage. then when I tried to measure resistance it gives me a reading of 3500 ohm while there is no resistor ...
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4answers
266 views

Do i need a resistor in this led circuit?

I have made a circuit with two (3v) LEDs in series. Connected to a 5v supply from an adapter with usb. (1.5Amp) I belive in series circuit each led gets around 2.5v which was enough to light them. ...
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51 views

How does an e-cigarette dry tank protection sensor work?

E-cigarettes work with a resistance coil which heats liquid into vapor. Some e-cigs have a dry-tank protection, which senses when the coil does not have any liquid to heat, to avoid it getting too hot....
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1answer
34 views

Finding Equivalent Resistance - does order matter?

Conceptual question: When you have a super complicated circuit, does it matter which node you start at when finding equivalent resistance? How about capacitance?
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24 views

Role of independent and dependent sources when calculating equivalent resistance

There are plenty of topics about this question, but I did not find a precise answer. Let's consider two points A and B of a generic circuit and suppose you want to find the equivalent resistance ...
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1answer
43 views

Reading of megohm during ground check

During the check of pins on connector with a multi-meter, one of the pins that goes through the relay to provide ground signal, I am getting 8MOhm (8 megohm). I should not be getting anything on that ...
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23 views

Thermal resistance of Thermal Interface Material

Can anyone please give information how to calculate the thermal resistance of SIL PAD "TSP A2000" from make Berguist. from The data sheet its specified thinness is 0.254mm, Thermal conductivity (W/m-...
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1answer
103 views

How a circuit get short

I am a high school student learning about the circuit, and how the current choose the path with low resistance, I have seen circuits and how one of the resistance among the other resistance get short....
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52 views

Find armature resistance on DC shunt generator

A DC self excited shunt generator has a field resistance of 160ohms generated emf is 420v and supplies a load of 55kw how would u go about calculating armature resistance when terminal voltage is 408v ...
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38 views

Thevenin Resistance in a op amp circuit

I created this circuit and I am struggling on trying to figure out the Thevenin resistance for this circuit.
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1answer
82 views

How can a light bulb run on different voltages (USA and EU)?

There is a concept in EE I don't understand. In Europe we have a 230 V supply voltage and in the USA e.g. 120 V. Now the thing I don't understand, how can I use my charger( or a light bulb) in ...
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22 views

To evaluate equivalent resistance of the circuit by star delta method

How do I evaluate this circuit via star delta method?
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1answer
32 views

ajustable resistance and MP2307

i try to make a current 4.2v with the switching regulation methode as you can see in the attached picture. The problem is that when i ajuste the voltage manualy from the ajustable resistance to 4.5v ...
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36 views

What is the Rseen from this node?

In the text book I am reading (CMOS Analog Circuit Design by Razavi) the author wrote that the Rseen from node N is (1/gm7), however when I derived it myself I found that the Rseen is ro4 // ro6 (...
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1answer
63 views

Calculating heat generated by resistance wire on 3 phase current

I am designing a heating element consisting of resistance wires coiled around a tube to heat water flowing in the tube. All three heating elements (loads) will have the same resistance and will be ...
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0answers
59 views

Best conductive ink mixture for potentiometers

Im 3d printing a model for a 2 axis potentiometer, and I need a carbon ink mixture that will hold up to the copper wiper, and produce around 10kOhm resistance in a line around 1mm*6mm. Searching ...
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40 views

AC resistance of LVAC transmission line

I'm currently working on a project to determine the transmission losses in an LVAC line, as part of an off-grid distributed generation system. The manufacturer of the cable has given me a DC ...
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1answer
47 views

What additional factors need to be considered when calculating voltage drop?

Considering the following formulas for voltage drop, what additional factors need to be included and how can resistance be derived to thoroughly calculate theoretical voltage drop for multiple ...
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30 views

Bad headphone driver resistance

I have a pair of ATH-M50 headphones where the right side has stopped working. I took them apart and measured the resistance at the L/R terminals on each driver. The good one measures about 35 ohms ...
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57 views

Calculating source voltage in circuit

Given the circuit I have to find the source voltage S and unknown resistance R3. It is stated that the power dissipated in R6 = 3 ohm is 0.75W. How should I attempt to solve the source voltage where ...
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1answer
81 views

120 Watts and 7.2 Volts, how many Amps?

For a project I need to switch on a simple handheld vacuum cleaner with an Arduino. I am thinking of using a relay or mosfet. I opened the case and a 7.4 V 2200 mAh Li-Ion battery powers the motor, ...
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1answer
96 views

Multimeter not picking up a resistance

I am making a set of speakers using 34.5 AWG magnet wire, and neodymium magnets to make a voice coil. For my wire gauge and required length I should have ~3 Ω (DC), 4 Ω (AC). The issue is when I ...