# What is Resistors: Definition and 603 Discussions

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators.
Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity.
Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds and forms. Resistors are also implemented within integrated circuits.
The electrical function of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than nine orders of magnitude. The nominal value of the resistance falls within the manufacturing tolerance, indicated on the component.

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1. ### B The voltage between two points

In electrical circuit there are three resistors and a battery connected in series. After the first two resistors, there is a point connected to the ground. Why is the voltage difference between the ground point and the positive of the battery not 10 volts? In that circuit, I think that the...
2. ### Equation of resistance from given graph

From the graph: $$lnR(T)=\frac{-lnR(0)T^2_○}{T^2}+lnR(0)$$ I have assumed ##R(0)## to be the value of ##R## at ##1/T^2=0## and ##T_○## to be the value of ##T## at ##lnR(T)=0## From this I get, $$R(T)=e^{lnR(0)×\left(1-\frac{T_○^2}{T^2}\right)}$$ $$R(T)=R(0)^{\left(1-\frac{T_○^2}{T^2}\right)}$$...
3. ### Analyzing Bridge Circuit w/ Loop Currents

Attached is the example I am working out of a textbook that involves using the Loop Current Method on a bridge circuit. In the pictures attached I am following section 1.6.2 which produces loop equations (1.24) for figure 1.9. Figure 1.7 provides the direction of current. I am having trouble...
4. ### Finding Current in Resistors & Charge of Capacitor

Suppose the switch has been closed for a long time so that the capacitor is fully charged and current is constant. a)Find the current in each resistor and charge Q of the capacitor. b)The switch is now opened at t=0s. Write the equation for the current for the resistor of 15kΩ as a function of...
5. ### Calculating Input/Output Impedance w/ Parallel Resistors

Hello, attached are two screenshots showing a common emitter and the same with source voltage removes to find the input impedance. How is it that resistors R1 and RC can be placed in parallel to work out the input and output impedances? Examples i have seen only show straightforward...
6. ### Engineering Resolve Parallel Resistor Error: I Set Rtot = 0.168

Since the slope of the I versus V graph is equal to 1/R, I set Rtot equal to 0.168. So then I subtracted 1/0.168 by 1/9 and got 1/R1 =5.841. I then found R1 equal to 1/5.841 or 0.171 but it said I was wrong. Can someone tell me what I did wrong?
7. ### Nodal analysis of this circuit with 2 sources and 4 resistors

Here is the question a. Plot nodes in the problem and indicate how many equations will be obtained. answer: two unknown variables b. Use node analysis. Derive the system of equations for the voltages in the circuit. question: Did I calculate right V_a and V_b? C. Calculate the...
8. ### Engineering Need help answering questions (Voltage source and 3 Resistors)

Hello. I need help arriving to the answers to the following question above. You will find the circuit attached for Number 1 I though that crrent would be maximum when resistance is replaced with a wire but I couldn't get a an expression for ut. as for question number 2 I tried applying node...
9. ### Engineering Black box which contains 5x 1ohm resistors

You are given a black box with three terminals, as shown below. The box is known to contain five 1-ohm resistors. Using an ohm-meter, you measure the resistance between the terminals to be the following: A - B: 1.5 ohms B - C: 3 ohms A - C: 2.5 ohms Determine the configuration of the five...

11. ### AC circuit analysis involving resistors and inductors

Summary:: Hi anyone can explain me how to solve this circuit, finding the current I2 and I1? Really don't know where to start Thanks
12. ### Power dissipated in this circuit with 2 batteries and 3 resistors

Hi guys I am struggling to find the power dissipated in the total circuit , my answer didn't match the solution in the book the circuit is simple i used Kirchhoffs rules to find the following : loop 1 : $$10-10I_{1}-40I_{3} = 0$$ loop 2: $$20-20I_{2}-40I_{3} = 0$$ and $$I_{1}+I_{2}=I_{3}$$...
13. ### Electrical circuit problem (resistors, capacitors, inductors )

I did try redrawing the circuit at steady state , but I'm not really sure. I have attached the circuit that I tried drawing, I assumed the branch with the capacitors to be absent at steady state since current won't flow through them anyway. With this diagram I get the correct answer for Q 19 ...
14. ### Why Can't Current Flow Between Two Same Voltage Nodes?

The question is to find the resistance between points A and F. I understand that the resistor between OC can be removed. From this point onwards, resistor OC has been removed. Let the far right point of the diagram, where i5 and i7 exit from, be B. Is it possible to detach the remaining...
15. ### Calculate current through resistors

I'm trying to grasp the basics here, we know Us = 70 V and I want to find out the currents I1 and I2 through the resistors R1, respectively R2. I just need the steps explained, not necessarily the results, please. Thanks in advance!
16. ### Circuit problem with two sources and three resistors (Nodal Analysis)

Ans: 0.123A Tried mesh analysis and got it but didnt for nodal analysis

18. ### Operational Amplifiers & Resistors to form a Black Box

So basically I am trying to give an output of Vo = 10(V2-V1) From Figure 9 Example Gain of first Op Amp = Rf / R1, if R1 & R2 are equal. What's throwing me off is using 5 resistors to create a circuit rather than 6 or just 3. My initial thoughts were the following: To use the first loop...
19. ### How do pull up and pull down resistors remove electrical noise?

I’m doing a project with my Arduino, and I’ve seen some tutorials on YouTube explaining how to use pull up or pull down resistors to make the input values on the board reliable, basically either a 0 or a 1 without any random changes from other em sources. The only thing is I still don’t...
20. ### Designing Balancing Resistors for Series Capacitors: Factors Affecting IR

I am lookin designing balancing resistors for series capacitors and understand that I need to consider the leakage current from the capacitors. I am trying to determine factors that would case the insulation resistance to decrease over time so I can design around that.
21. ### Electromotive Force, Batteries, Resistors, and Potential Differences

I have attached a small excerpt from my digital book where they start talking about emf. I am very confused. Let me explain what is confusing to me so that you can clear up what's bothering me. They start of by saying that an emf device pumps charges by maintaining a potential difference...

23. ### Calculation with this electric circuit (battery and resistors)

Hey, I am struggling a bit, als I try to solve this problem - I‘d say all five statements are correct, but it is said, that one must be incorrect
24. ### Two batteries and two resistors circuit - wrong possible answers ?

It's ABCD question with answers attached. Problem is that, I don't think that neither of those are correct. From KVL the equation seems to be i = (E2-E1)/(2r1+2r2 + R). I've attached images of the circuit, answers, and my solution. Can someone please point me if I am wrong, and if yes, where's...
25. ### Using Kirchhoff's laws for multiple batteries and resistors

Hey everyone! Had an attempt at this circuit question, but wanted to check if I got the set up right in order to find the current in the 3rd wire? Here is what I have done Thanks!
26. ### Engineering Solve for R1 and G in circuit with Vs, VCCS, and 2 resistors

I've gotten to the point where I've hit a roadblock and am not sure what step to take next. I started by using KCL on the bottom node as suggested by the problem, then used KVL on the left mesh, but I still have ##i_{v_s}## which I'm not sure what to equate it to, so that I can pull it out of...
27. ### Two resistors connected to a battery

I honestly have no idea how to do this problem whatsoever. My teacher didn't show an example like this before.
28. ### Circuit Analysis Question -- 2 sources and 4 resistors

Now, I know this question can be solved using Kirchoff Voltage rule, but the question expliciitly wants me to use power supplied = power absorbed. Hence taking V0 to be x, I can't still seem to calculate. Any ideas? Power supplied = (60)(3) + (5x)(3) = 180+15x Power absorbed = 72+ 56 +28 + 3x...
29. ### Kirchhoff's law: Circuit problem with multiple batteries and resistors

Struggling to see if I am doing this right or not from a section of a question I have been given I have drawn out a sketch of the circuit again, and labelled as to what my 1st and 2nd closed loop to be to then apply Kirchhoff's 2nd law I get a negative I_2 current which just indicates that...
30. ### Maximum voltage that can be applied to DC circuit with resistors

I see that ##V_{ac}=V_{ab}+V_{bc}##, with ##V_{ab}=I_1R_1=I_2R_2## and ##V_{bc}=I_3R_3##. However, I don't see how to express mathematically the maximum value of ##V_{ac}##. Could someone please help me with this task?
31. ### Resistivity equation relating to equations for resistors

1. Would k be p/π? (since resistivity of a material is a constant property and π is a constant) I understand that typically R = pL/A Therefore, would the equation be R = k(x/(d/2^2)) Confessedly, I truly am baffled.2. R total = sum of individual resistors (in series) R total = R1 + R2+R3...+Rn...
32. ### Finding the currents in this circuit (2 voltage sources and 3 resistors)

In my attempt, I tried 1) I1 = I2 + I3 Then set up these two equations based on Kirchhoff's second rule: 2) U1 = R1 (I2) + R3 (I3) and 3) U1 + U2 = R1 (I1) + R2 (I3). From what we have 10 = 0.1* I_2 + 0.2 * I_3 22 = 0.1* I_2 + 0.02*I_3 I_3 = 50 - 0.5 I_2 That means I_2 = 233.3 A I_3 = -66.7A...
33. ### Kirchhoff's Rules for analyzing this circuit with batteries and resistors

Summary:: Choosing the direction of the loop and the current I am attempting to work out Example 1 in the link provided. https://courses.lumenlearning.com/physics/chapter/21-3-kirchhoffs-rules/ When solving for loop aefgh, I get: I1R1-I3R3-I3r2-E2 =0 I chose the current to continue to move...
34. ### A circuit with switches, capacitators and resistors

To solve this question first I calculated the potential energy the capacitor A stored. It's equal a: Ca.V²/2. Ok, so when switch S1 is open and S2 is closed I calculated the equivalent capacitance as if they were in series --> 1/Ceq = 1/Ca + 1/Cb --> Ceq = (Ca.Cb)/(Ca+Cb). So I used the formula...
35. ### Engineering Designing an adjustable voltage source using only resistors and a pot

I need to create a powersupply that takes in a +5 and -5v and has an adjustable output that varies between -2 and +2 v using one potentiometer. I already came up with a design myself but it did not work. I need some help figuring this out. I think my idea for how to get specific positive or...
36. ### Why Are Some Resistors in Parallel While Others Are Not?

My attempt at a solution: I can see the two resistors at the bottom are in parallel as shown on the circuit diagram attached, but I'm failing to understand why there's a third resistor in parallel. So I made it one effective resistance as R/2. Then I proceded to think the circuit short circuits...
37. ### Two cells in series with internal resistors -- calculate the current

Can somebody explain this please? I don't understand this.
38. ### How Are These Resistors in Parallel

I’ve included an image of a solution to a problem from my textbook. Part of the problem is to find the equivalent resistance of the given circuit. In the solution they seem to be treating the resistors as if they were in parallel. I don’t understand why they are doing this. For the two...
39. ### Circuit analysis: Six resistors and two batteries

Problem Statement: ) A circuit is constructed with six resistors and two ideal batteries as shown. The battery emfs are ε1 = 18 V and ε2 = 12 V. The values for the resistors are: R1 = R5 = 55 Ω, R2 = R6 = 110 Ω, R3 = 44 Ω, and R4 = 117 Ω. The chosen positive directions for the currents are...
40. ### 2-Resistor, 2-Capacitor Circuit with Switch

I already did part a and got the correct answer of 4.8 microC. However, I am unsure how to approach part b, where the switch is closed and apparently the two capacitors end up with different charges. For part b, since there is a path between the two capacitors, I don't know if I am able to...
41. ### How to calculate Resistors in a circuit ?

here is the question below with all the possible answers, if anyone can help it would be appreciated
42. ### Resistors in Parallel or Series?

Given that they're all on the same branch, I had assumed that they were in series with one another. But with the middle resistor having being on the middle of three branches, it looks parallel. Like I said, I have a feeling it's in series (making the answer 3R). This question is from a past...
43. ### How to calculate what a voltmeter measures with multiple resistors?

I tried to solve it by removing the voltmeter and simplifying it to just one resistor, then calculate the individual volts and then the deltaV, but still didn't found the answer, can you guys help me?
44. ### I need to calculate the equivalent resistance

Homework Statement The circuit is the one in "Fig.4" I need to calculate equivalent resistance between A and B. This is what I've tried: I think that the first resistor is shorted by that wire connected between A and E. Their answer looks like this, in fig 2.2.1. I'm not sure if their...
45. ### Energy dissipated in the resistors in a 2 mesh RC circuit

Homework Statement Hi mates, I have problems solving the third part of this exercise, I've already done all the previous calculations. Given the following circuit, where the switch S is open, the power supply = 50 volts and: The initial charge in the C capacitor: QC = 0 coulombs The initial...
46. ### What is the use of 0 Ohm resistors?

Today, I found that there exists something like a 0 ohm resistor: https://www.electroncomponents.com/0-e-ohm-resistor-resistance-zero?filter_name=0%20ohm%20resistor Don't look at the image in the page I can simply connect two points in a circuit with a good quality copper wire, thereby...
47. ### Equivalent Resistance of Parallel Resistors

I did this for fun, if you want to do it in an unconventional way, this would be useful in programming. For ##n## resistors in parallel: $$R_{total}=\frac{\prod_{i=0}^{n-1} R_{i}}{\sum_{i=0}^{n-1}(\prod_{j=0}^{n-2} R_{i+j \mod n})}$$
48. ### Why does current choose the short circuit path?

I've seen answers saying that electricity takes path of least resistance, I know this and there is no need to explain this for me. A forum's answer told me that the electrons initially flow through to the path with resistance and eventually becomes congested (redirecting the remaining electrons...
49. ### Equivalent resistance with a capacitor

Homework Statement So I need to find the equivalent resistance for the following RC circuit to calculate the time constant, but I got stuck in terms of finding out the equivalent resistance. Homework Equations V = IR The Attempt at a Solution So the thing I am not sure on is how do you...
50. ### Combination Circuit Help (pic)

Could somebody help me out with this combination circuit? The answer that I get is 62K but that is not one of the answers. At first, I thought the 10kohm and 20kohm wherein series and the other side as well. Then I thought they are all in parallel because of the different current flow they all...