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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53 views

Increase resistance to turn on a light bulb

I’m wondering if it is possible to use a potentiometer to turn on/off a lightbulb in a binary manner. I’m thinking high resistance = light on. Low resistance = light off. Is there such a circuit? ...
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Trouble understanding thevenin's model from AoE Lab

I am using the AoE lab book to teach myself electronics. I am on the voltage divider section, and I am confused at their simplified explanation. I'd like to explain it a different way, but I am not ...
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What is the difference between transresistance and differential resistance?

Transresistance is defined as the change in output voltage over change in input current. While differential resistance is defined in the same manner. So what is the difference ?
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Calculating resistance for integrated circuit with logical gates, so that the circuit works properly

I have found this task with its solution: For the circuit shown below calculate \$R\$ so that the circuit works properly. All gates belong to the \$TTL\$ series. Solution: $$\begin{...
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How to find equivalent resistence of this mixed circuit?

Find equivalent resistance, the current in R5, Voltage of R2 and power of R10. Actually, I don't know if my attempt is right. So, you would point out where there are mistakes, pleased. R10 and R11 ...
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Measuring Voltage drop across MOSFET 2N7000

My setup is 2.1V on the gate. A 330 Ohm load between Vdd and drain. And Source to ground. I stepped Vdd from 0V to 9V in small increments and measured the current through Vdd to ground. Got currents ...
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71 views

Fraction resistance and negative resistance

Is it possible that the resistance will be fraction or negative number and what's happened?
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162 views

Can a resistance be negative?

I have to calculate the value of a resistor so that my circuit has a certain equivalent resistance. This is the circuit, and here are the values: ...
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55 views

Finding R equivalent

simulate this circuit – Schematic created using CircuitLab When finding Req between M and N i can't understand why current isn't flowing in R3 and R4.
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Current and resistance

Can anybody explain why my tongue gets a reading on a multimeter. Do I have a current? Why do i have resistance? Why do some things have resistance? I am very confused.
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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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Ground with one sensor vs multiple sensors

I'm pretty new to the world of electronics and was working on an Arduino project using load cells and HX711 amplifiers. The project consists of four HX711 connected to the Arduino and Pi, with all ...
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Circuit solving problem

I am a high school boy and came across this question: I have solved this question by KVL, but how do I solve this question by potential distribution method? What I have tried :) I assume two ...
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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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How to calculate equivalent resistance in this circuit?

What is the way to calculate the equivalent resistance between this two terminals? This is pretty simple circuit but i'm not sure what is ok to do and what isn't
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71 views

Is power balance a relevant factor in the consumption of a house?

Where I live, houses receive up to three phases from the electricity provider. There is a company advertising a power balancing service. They claim that if one of the three phase cables is overloaded,...
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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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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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Reducing the circuit

I am high school boy, our teacher gave us circuit and we have to find out the equivalent resistance. . Our professor gave us idea that we can solve this question either by either superposition ...
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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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Are these 2 resistors in parallel?

So I had a circuit to analyse and I needed to find the equivalent resistor and then I arrived to a confusion. Are R1 and R3 in parallel? Here is the circuit. simulate this circuit – Schematic ...
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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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1answer
35 views

Cable length and voltage drop in offgrid solar installation

I have connected my Lithium-ion battery pack(11.1v 100ah ) with my Epever MPPT charge controller using 5M length of 8 AWG cable. when i put load which consume around 12A , the charger controller shows ...
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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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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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45 views

Confused about Thevenin’s Theorem

I have a hard time trying to understand why Thevenin’s Theorem is the way it is. As per the diagram below, I understand why we take our “Thevenin resistance” that way. But as far as the voltage is ...
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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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84 views

Conductivity of liquids (3D resistor network)

Hi I'm an electrical engineer but have not seen this problem before. I'mn trying to measure/calculate the resistance of a liquid. Background: I'm working on an electronic device that can come in ...
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Is the maximum current a resistance can draw limited by the maximum current available (current rating) in the power supply?

Let's say I have a single phase power supply at 100 V and 10 amps at my wall outlet. If I were to connect a very low resistance element (say 0.1 ohms), using Ohm's law I could say the resistance draws ...
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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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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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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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59 views

Do transistors naturally have resistance on base, collector, and emitter?

I'm using a circuit simulation app called EveryCircuit, and for the npn transistor settings it has forward beta, reverse beta, base resistance, collector resistance, and emitter resistance. I'm a bit ...
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Does a correctly sized resistor protect low voltage components from a high voltage source?

Let's say that I have a 37v DC source that I would like to reduce to 12v so it can run a 12v light bar (a string of 6 leds and I assume a resistor to limit the current). I measure the resistance of ...
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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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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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1answer
121 views

Low resistance digital potentiometer - alternatives?

I've done quite a bit of searching online and can't find a solution to this (probably trivial!) problem: I am looking to replace a resistive fuel level sensor in a car, with a solution which can be ...
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Voltage gradient in voltage difference across a resistor

If I have a voltage difference V from terminal 1 to terminal 2 of a resistor. I take an arbitrary point P along the resistor, between terminal 1 and terminal 2, and take terminal 1 as a voltage ...
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Why do fuses burn at a specific current?

We usually specify the maximum current that a conductor (such as a fuse) can handle without burning. But doesn't the conductor really fail when a certain amount of energy/heat has been dissipated in ...
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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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107 views

What is the circuit formation in this electric blackbox?

It should be a simple question from my exercise book, but I could not find the solution for some reason. As illustrated, in an electric blackbox, there is one switch (k), one 3-volt battery, three 1-...
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Why does a pull down resistor eliminate floating input

Ever since I connected a button to an Arduino for the first time, I've wondered how does the resistor prevent floating input from happening? I've read several answers to similar questions, seen videos ...
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My ohmmeters don't behave as the book “make: electronics” describe

Here's the (low end) devices I own. One is an HoldPeak HP-90EPC, the other is an GBC KDM-110 I am following the book "Make: Electronics" by Charles Platt and I am at the very beginnings, where it ...
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Can a trim-pot wiper or contact point gets oxidized over time?

Can a trim-pot wiper or contact point gets oxidized over time? For example when a potential (high) current is flowing and the contact point of the wiper on the resistive element heats up a little. I ...
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Why does the cable resistance jump from a low value to high value at a particular frequency?

I am not well versed with transmission line theory so if you can redirect me to relevant material I'd be grateful. So I used Agilent 4294A to find resistance of a 2 metre long shielded twisted pair ...
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Velostat sensitivity to temperature

Velostat and some other type of conductive fabrics change resistivity based on pressure, but I did not found information about its sensitivity regarding the temperature. Is the velostat resistance ...
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What is initial contact resistance in relays?

I am reading datasheet of a relay. I see a term, initial contact resistance in relays. What is the definition of this parameter? Thanks.
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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 ...