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Questions tagged [resistance]

It's a measure of how much an 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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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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3answers
25 views

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
79 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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Critical resistance situation

I'm in a situation where my resistance changes between two states (infinity and 500 Mega ohm ).I want to be able to notice a change when it switches from one state to the other state. Unfortunately I ...
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0answers
25 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
37 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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34 views

What is the equivalent resistance between A and B of given figure [on hold]

How can find the equivalent resistance between A and B? R denotes resistance of the resistor.How can I do it ? How can solve it by parallel and series method or headstone bridge method. Indeed answer ...
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62 views

What is the equivalent resistance between A and B [closed]

how can i do it.I tried .I tried a lot how can I do the problem it is very difficult for me to calculate what is the meaning of angle in this problem
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4answers
112 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
68 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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6answers
2k views

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
82 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
60 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
61 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
91 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
43 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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1answer
75 views

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
68 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
43 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
76 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 ...
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2answers
96 views

How can I make a model of a single wire CAN bus cable?

I'm currently working on a project of analyzing the latency of a CAN bus network with transceivers and without transceivers. The latency parameter here will be analyzed with the effect of bus line ...
0
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1answer
48 views

Ohm's Law in Practise

When the AUX pin of a stereo is connected to my mobile phone's audio female port, I just measured the voltage at the end of this AUX pin(No load is connected) approximately 2mV using a DMM . But when ...
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2answers
66 views

True value of skin resistance

When I googled about skin resistance I find people mentioning values as low as 500ohm but usually around 10-100kohm. When i measured the resistance of my own skin by putting the probes on the inner ...
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2answers
51 views

Norton equivalent resistance of zero?

I am trying to analyze this circuit using norton. Load (20 Ω) is connected between A and B. I have removed the load and calculated the norton current to be -2A. Now I try to calculate the norton ...
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2answers
58 views

How to split up voltages

I want to power up bluetooth receiver module (input voltage 3.7) and audio amplifier module which accepts only 2.4 - 3.7 voltage, exceeding which already burnt the IC. So i got new one. I'm having 2 x ...
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2answers
123 views

Is a resistor required to power a LED strip with a 9V battery?

I have a 7020 white light LED strip, which includes a resistor on each module as you can see: I would like to power a little strip of five of these modules with a 9 V battery, but I wonder : 1- Do ...
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2answers
60 views

A low power circuit to measure large resistances

I am trying to measure resistances in the range 20 kohm to 1 Mohm. Initially, I was using a constant voltage source, but the power consumption when the R = 1 Mohm is very large. I want to use as ...
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2answers
52 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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2answers
73 views

Exactly what type of resistor is being referred to in this diagram?

I'm trying to control an RGB LED strip using a NodeMCU. I have been following the guide linked here. However, the diagram included in the diagram is rather unclear, especially for someone like myself ...
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1answer
59 views

Voltage across and current through the LED load

Assume that an LED of rating 3V and 20mA is connected in series with a resistance and a supply voltage of 9V is applied across it. For the required ratings of LED, I chosen a resistance value of 300 ...
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4answers
121 views

How to find the total resistance of this circuit

Without giving resistor values, what are the steps to breaking down this circuit to find total resistance?   Edit: Like this?
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1answer
66 views

output resistance of discrete amplifier

I have the three-stage amplifier below. I am interested in finding the output resistance of it. Just wanna check if am doing it correctly? Thanks simulate this circuit – Schematic created using ...
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6answers
113 views

Why doesn't voltage drop across this resistor when transistor is off?

The following excerpt from a book explains the functioning of the circuit below: When V_in < V_th (device threshold voltage), the supply voltage (V_dd) is measured at the outlet. When V_in is ...
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1answer
156 views

Parallel connecting USB power for higher currents [duplicate]

I am trying to find any way in which I can have a higher power output from a USB power bank, by combining multiple USB ports in parallel. The USB power bank has 3 outputs, one rated at 2.1A and the ...
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2answers
50 views

Voltage Drop for Power Supply Testing

I recently bought a 10-30 kV DC, 8-10 mA power supply that I am looking to test before its incorporation. However, the retailer advised me that I should place a load on this power supply - as one ...
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5answers
3k views

Do resistors of same color code but different size have the same resistivity?

Picture has three resistors with the same color code (in this case brown-black-black) but different sizes. My question is if they have the same resistivity because I know resistivity is indicated by ...
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4answers
124 views

Does reactance increase noise?

Impedance is made of resistance and reactance which is capacitance and inductance. I read that increasing resistance increases noise, but what if capacitance or inductance is increased, does the noise ...
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2answers
70 views

Decreasing and reading output of a sensor (0 - 10 V) using a voltage divider - Output impedance

I have a pressure sensor giving an output between 0 - 10 V. I want to read and save the value using an arduino, so I am using a voltage divider (https://learn.sparkfun.com/tutorials/voltage-dividers) ...
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3answers
39 views

Thermal resistance - Temperature transistor

I have a transistor with Vsupply = 24VDC, VCEO = 45VDC, ICE = 20mA. How to calculate the delta T (rise in temperature) of this transistor. I would like to know what thermal resistance I may have at ...
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2answers
59 views

Circuit resistances with activating switches

Electronics beginner here - My current project is an automotive project whereby I want to recreate a small circuit which uses resistors to feed the car's ECU with information as to what action to take....
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2answers
78 views

What is the function of the dippers in a slip ring liquid starter?

The liquid starter is one that uses a washing soda solution and water in a tank. From what I've read, the dippers are attached to a shaft controlled by a small motor to lower the dippers into the ...
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2answers
59 views

Output impedance of a 4mA to 20mA current loop

I have the most basic of basicness circuit. The implementation is a XTR115UA IC with a 40µA - 200µA input (based on sensor voltage) which is amplified to the desired 4mA to 20mA current in the current ...
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2answers
66 views

Calculating Resistance

Can somebody tell me why R_o2 is RD Why dont we take Rs into consideration ? Their answer is Ro2=vt/it = Rd My question is why didnt they take in consideration Rs and the current source?
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510 views

How to calculate MOSFET internal gate resistance?

I was trying to figure out how to calculate the internal gate resistance of the MOSFET. For the purpose of analysis, Let's take the MOSFET as - BUK7Y3R5-40E From most of the documents I read, best ...
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3answers
89 views

Thevenin Equivalent Resistance of complex circuit

I'm trying to find the Thevenin equivalent of a circuit of which I have already found the Thevenin voltage. Unfortunately I can't figure out how these series parallel combinations work to find the ...
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2answers
380 views

Why would it be bad practice to limit current with just a resistor? [closed]

I am sure I am incorrect, but nobody can tell me why I am incorrect. I have some LEDs that require 1amp. My DC source 52v @ 2.6amp DC power source (constant current technology) A proper solution ...
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2answers
95 views

Measurement of total AC resistance (including radiation resistance) of a coil using LCR meter

If we measure AC resistance of a coil using an LCR meter (or impedance analyser), does it include both ohmic resistance and radiation resistance? I understand that the radiation resistance is ...
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1answer
45 views

Inductor dc resistance simulations

How can I simulate the dc resistance/R_dc of a spiral inductor? Here's the circuit I have: I simulate the inductor with a dc source and get the series current from a I_probe. Then calculated the dc ...
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0answers
54 views

Designing a heating element rated for 3kW 240VAC - specs?

I am terribly new to resistance heating, but I understand the general concept. I'm looking to design a heating element using coiled NIC80. If the applied wattage is 3kW and power supply is 240VAC, ...