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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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Is negative resistance practically available?

I learned that negative resistance could be simulated by involving active devices like op-amps and others. My question is whether it is really practically feasible to be used when making an AC circuit ...
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910 views

Measuring a small resistance, ~0.001 ohm

I have a low resistance resistor that I would like to use to measure the current through another circuit, but first I need to accurately determine its resistance. Its data sheet says it is 0.001 ohm +...
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49 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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31 views

Resistor's behaviour at high frequencies

Looking at the impedance vs. frequency graph 1) At low-frequencies Z=R and hence it would be a straight line. 2) For mid-frequencies, Z decreases possibly due to capacitance, but I'm not sure ...
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50 views

Resistance range indicator

I am facing a huge task of checking 1000s (1000s per box and I have nothing less than 20 boxes) of wire wound resistors purchased by my company. I have been assigned to check the resistance value of ...
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2answers
66 views

Is my understanding of current, voltage, and resistance correct?

Im currently a senior in highschool. So I know that voltage is the potential difference per unit charge, or from my understanding the work done to move a unit charge from point a to point b without ...
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61 views

Power absorbed by load resistor

Can someone double-check where's the mistake? The system didn't accept my answer. TASK: Find the maximum power absorbed by the load resistor, knowing that: $$E = 6.6V; R_{1} = 12.1Ω; R_{2} = 14Ω; R_{...
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1answer
34 views

What is the parasitic resistance due to an IC package in a mosfet? (or any package)

How much resistance does the package of an IC contribute to the paraistic resitance of a circuit? (most applicable to mosfets)
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29 views

Series/parallel combination of resistance/capacitance in an RC circuit (wrt LCR meter readings)

I have this equivalent circuit I am working on. I have to find out individual values of all components in it. I can measure resistance, capacitance and impedance of the whole circuit. I am not sure ...
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38 views

Why the input resistance of a common emitter amplifier is like this?

I am trying to find the input resistance of this BJ common-emitter amplifier: I replace the transistor with the hybrid-pi model It appears clear to me that the input impedance will be \$ R_{in} =...
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2answers
70 views

Conceptual paradox with resistance in loop/node analysis

There are loop/mesh analysis and node analysis corresponding to Kirchhoff’s voltage law (KVL) and Kirchhoff’s current law (KCL), respectively. Let's consider three elements, R,L,C, connected ...
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29 views

Conductivity formula for Metals

Is there any expression for the direct change in conductivity of metals with temperature ? I am aware of change in resistivity with temperature.
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44 views

What is the current through this parallel circuit?

I'm trying to solve the attached circuit for I1 and I2. I think I1 is just 5A but I'm not so sure about I2, I think it might be just 10/5=2A but I'm not sure if the voltage in the top right part is ...
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Problem understanding an exercise regarding impulsions

So, I'm having quite some trouble understanding and solving the following exercise. We're given the following montage We are told that the following square signal (called Vin) is applied Now, we ...
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1answer
44 views

Why is there a minimum input resistance?

I was looking at this multimeter, and it says, Output rate:     0.1 V/A (use with a device having a 1 M-ohm input resistance or higher) Where can I read why this minimum resistance is required? ...
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52 views

OBD-II scanner connector's pinout check

I've got two OBD-II scanners in my possession and my car's OBD-II works through an ISO 14230-1 connection (K and L line). Both scanners work with my car, but I recently discovered that a resistance ...
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2answers
85 views

How can I calculate length of wire, given its gauge and resistance?

As the title suggests; I am trying to calculate the length of a wire given its gauge and resistance in ohms per 1000 feet. I also have the amount of voltage drop, which is 1.1 V. ...
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139 views

Output resistance of MOSFET circuit

I am trying to find the output resistance \$Rout\$ of this circuit consisting of 3 n-type MOSFETs. It is given that all 3 MOSFETs have \$g_m=4 mA/V^2\$ and output resistance \$R_o=100k\Omega\$. ...
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79 views

How to calculate secondary winding max current output?

I have removed a UPS transformer. It is a Class B Viking transformer. Its primary side has 4 wires coloured black, green, blue and yellow. I found resistance as follows- 1. Black to Green - 17 ohm 2. ...
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118 views

Uses for 49.9Ω resistors? [duplicate]

It seems that both 49.9Ω and 50Ω resistors are a thing: https://www.mouser.co.uk/Passive-Components/Resistors//N-5g9n?P=1z0wnltZ1z0wljo https://www.mouser.co.uk/Passive-Components/Resistors//N-5g9n?P=...
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1answer
66 views

Find potential difference between nodes A and B in circuit below

By KVL and KCL Ix = 4A and Iy=Iz=6A The potential difference between A and B = Va - Vb = 6 +8Ix =38V I don't understand how we calculated the potential difference using KVL and KCL
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32 views

Can somebody explain the none repeatable reading of force sensing resistance

I read the datasheet for force sensing resistance datasheet saying that : The main problem with using a Force Sensing Resistance is that it typically produces non-repeatable readings, due to its ...
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3answers
86 views

How can I find out which resistor is short-circuited and can be ignored?

I don't understand how the current flows in the circuit below. How do I deal with the wire between nodes c and a, a and b, g and d. Why is the 5 Ω resistor shorted out? I am having a little trouble ...
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Q: Need help acquiring target resistance from Digi pot

I have a MCP4162 lying around and I want to start using it to control the gain of my amplifier circuit, However I am having the hardest time trying to predict the digi pot resistance. Not sure if I am ...
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2answers
46 views

Selecting temperature probe for home use with long cable / low power [closed]

I would like to monitor the temperature outside my home. The sensor has to be located at least 20m cable length from the display unit. Whole system should be powered by a battery (doesn't matter which)...
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1answer
63 views

Input Impedance of a diode connected MOSFET

I was trying to derive the small-signal input impedance of a diode-connected MOSFET (figure included), and came up with this expression. Is my method correct? I have been reading about methods of ...
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1answer
39 views

Finding the energy over the capacitor in DC

I tried using Thevenin to solve this and found Rth = 3 and Vth = 12 but this is way off the correct energy of the capactor (the energy is 4J).
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1answer
28 views

Removing/Subtracting Lead Resistance Using Op Amp Circuit

I'm working with RTD sensor, and need to use Op Amp circuitry. Can someone explain to me how this Op Amp circuit work to remove the lead resistance? So that Rw1, Rw2, and Rw3 vanish, hence the ...
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3answers
4k views

Under what circumstances would 5V@2.1A be lethal? [closed]

Besides obviously sticking an output of 5V directly to the heart. Are there areas inside the body where resistance in ohms is so low that a 5V electric potential would be fatal? I got into an ...
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2answers
124 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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0answers
32 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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1answer
33 views

Thevenine equivalent using loops

I'm trying to figure out the Thevenine resistance of this circuit using loops. Perhaps loops is the wrong way to go? I've made the circuit using a breadboard and found out that the answer should be \$...
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1answer
60 views

How do I evaluate the equivalent resistance between K and M?

The equivalent resistance between K and L is given 3Ω. How do I evaluate the equivalent resistance between K and M? I couldn't think of anything so far. Could I get your dear assistance?
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Contact pressure vs contact area

I'm learning to weld. I've realised my earth clamp is limited. The spring is weak and its contact area is small as it's tooth shaped. Researching better clamps, I see clamps which have threaded bolts ...
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1answer
82 views

Why does the resistance change when additional resistors are added here?

Please excuse what is probably a very simple question. I don't know the correct terminology to describe this better than "added here" as these don't appear to be "in parallel" or "in series" since ...
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0answers
29 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
38 views

Why is temperature coefficient divided by reference resistance?

In a book I am following, it is assumed that the temperature resistance relationship is linear. I would expect, then, that the resistance at a given temperature would be given by the formula $$ R_{t}...
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4answers
132 views

Under what circumstances would the large internal input resistance of an actual op amp affect circuit operation?

I was able to find a lot about why the input resistance is high and basically infinite. I understand that the input resistance is high so that it doesn't become a load on the signal. I also know that ...
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1answer
76 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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LED not achieving max current

I have a project that is powered by a 12v power supply. I need as bright of an LED as possible and decided to use this 9v LED. According to the datasheet, its max current is 1A, which is what I would ...
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3answers
113 views

Find Voltage between two terminals

I have the circuit below and I need to find the voltage between the terminals A and B, which steps do I need to follow? And if there are several methods to do so, what are they?
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1answer
62 views

Calculation of transmission loss of a power plant

What is the transmission loss due to heat if my power station produces electricity at a power of \$5 kW\$ and the electricity consumer is \$1 km\$ away? It is a copper line with a material constant ...
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1answer
81 views

Can a Dependent source be dependent on itself?

I am looking for the Thevenin Resistance here. However, I have no clue what to do with \$i_b\$ and the source dependent on it. This is the entire circuit. \$i_b\$ is the current through the 5\$k\...
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2answers
1k views

Shunt resistor, what value should I expect when soldering on PCB?

I am using a 10 mohm 1% shunt to measure current via voltage drop. My circuit is on a breadboard... It behaves as if the shunt has a value of ~30-40 mohm instead of 10 mohms. I double checked this ...
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3answers
100 views

MOSFET gate resistance's power rating

I wanted to verify the following or get some helpful pointers. So, I have a gate driver which can supply a maximum current of 0.5A , and I am driving a MOSFET Vgs of 15V, based on these two ...
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2answers
49 views

Is the resistance between collector and emitter is lower that of the path between collector and base? [closed]

If no, pls tell me why. And if yes, my question is how can the path C-B-E be have lower resistance than that of B-E? Shouldn't the resistances of BE and CB add up cause they're in series?
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what is the equivalent resistance of this configuration? [closed]

consider the blocks as resistance and the numbers as their respective resistance.count it's equivalent resistance across A and B. I just want some hints.this is not my homework problem.I am just ...
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1answer
84 views

Resistance between terminals A and B [duplicate]

I found the Req of the whole circuit at first, then tried re-assembling the circuit and still I couldn't get the right answer. Any idea on how I should proceed in this exercise? I'm not looking for ...
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1answer
52 views

Find the Resistance between Two Terminals [closed]

Let's say R = 49 ohms, and we want to find Req between a and d, how do we do that? Do we have to find Req for the whole circuit?
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2answers
78 views

Modeling a long single wire in a circuit?

I'm currently trying to make a model (equivalent circuit) of a long single wire with a resistor and inductor in series. Is this a proper way to do it? What I have done: Calculating the resistance ...