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. P

    Resistors: Questions & Answers Explained

    Homework Statement I'm not sure how to do these. Other resistor questions are relatively easy but these had me stumped. An explanation for them would be helpful since all I got are the answers. The first one is 9.6ohms, second is 0.55ohms. Not sure if this is advanced but I'm seeking an...
  2. C

    MHB Solving Resistors in a Circuit: Working Backwards

    Problem: I have found the total current running through the entire circuit. My problem is now I am trying to work backwards to determine the current through a certain resistor. I know when dealing with basic capacitors, voltage in parallel is the same, and charge in series is the same. Does the...
  3. I

    Engineering Resistors in parallel Thevenin circuit

    When calculating Rth, they took the parallel combo of he 40 kilo ohm and 160 kilo ohm resistors, then they added the 8 kilo ohm resistor that's in series with the combo. Maybe I'm having a brain freeze or something but how are the 40 kilo ohm and 160 kilo ohm resistors in parallel? They don't...
  4. P

    Are Charge Imbalances Present on Resistors?

    I know that in electric circuits charge imbalances can build up on capacitor plates, wire bends, and antennas. But is this also the case for a resistor with a voltage applied between its terminals? In other words, which of the following diagrams would be correct? Note that a + stands...
  5. Prashasti

    Resistors in series and current equivalence.

    "Resistors resist the passage of current through them." Then why the current through each resistor same in series combination? Suppose 'I' current is passing through a system of two resistors connected in series. 1. Won't the first resistor - which is directly connected to the positive...
  6. A

    When 1 mega Ohm resistors are used?

    When and "for what purpose"/why are 1 mega ohm (1 MΩ) resistors used in filters, such as high pass filters? Is it with regards to electrostatic discharge or impedance matching? What difference does it make, if I only use a 10 K ohm resistor, when the high pass frequency will be the same (by...
  7. J

    Engineering Circuit Analysis - Resistors and a battery

    Circuit Analysis -- Resistors and a battery Homework Statement Hello, if you see the attached I am trying to find the current I4.My plan was to find Voltage across R4 and use Ohm's law. Homework Equations V=IR The Attempt at a Solution I have simplified the circuit down(attached pic), I...
  8. J

    If there is really a potential drop across resistors

    How come capacitors receive the full emf In a circuit with a resistor in it? I plugged in 100000 into -t in the rc transient and it gives me the emf. Why? I thought you actually "lost" potential through resistors?
  9. J

    Potential Drop Across Resistor - Explained

    When one says there is a "potential drop" across the resistor, they do not mean the actual voltage has gone down right? They just mean the current has? But then I question that because since the current goes down then the voltage has to as well? I am fuzzy on this subject, can you explain...
  10. gfd43tg

    Optimizing RLC Circuit with Extra Resistors for Improved Performance

    Hello, I am working on this problem I am having some difficulty finding the right answer. A few points I'd like to expand on so that one can understand my thought process. First off, there is a standard table with the solution to series RLC circuits. I don't think I can use that table with...
  11. Rugile

    Calculating Voltages Across Resistors Using Ohm's Law

    Homework Statement Two resistors are connected in series to an ideal battery. When the voltmeter is connected in parallel to one of the resistors, it showed 6V; when connected in parallel to another resistor it showed 4V. When the voltmeter was connected in parallel to both resistors...
  12. E

    MHB When two resistors are in parallel....(rational functions)

    When two resistors, s and t, are connected in parallel, their combined resistance, R, is given by \frac{1}{R} = \frac{1}{s} + \frac{1}{t} If s is increased by 1 unit and t is decreased by 1 unit, what is the change in R?(I'm not really sure how to do this...help would be appreciated! Thanks.)
  13. M

    Physics Lab - Electrical Circuits with Resistors and Capacitors

    Homework Statement Hello, I am having trouble with a physics lab report I'm working on. I'm going to try and be as clear as possible. Basically, I'm using different values of R and C in determining tau, the time scale in a circuit's behavior. I used a circuit with a resistor and capacitor and...
  14. O

    Resistors in seriess-current is the same?

    resistors in seriess---current is the same?? So current is the same if you have resistors in series….but won't the current decrease because the resistors provide resistance to the current??\
  15. Saitama

    How Do You Calculate the Equivalent Resistance in an Infinite Resistor Network?

    Homework Statement Calculate the equivalent resistance of the resistor chain shown in the figure between the points a) A and B; b) A and C the resistor chain is infinite in both directions and each resistor has a resistance of R. Homework Equations The Attempt at a Solution I have solved the b)...
  16. K

    Engineering Circuit with Diodes, Capacitors, and Resistors

    Homework Statement Compute V3(t)-V4(t). The capacitors are initially discharged, the voltage source is turned on at t = 0, and the diodes’ forward voltage drop is negligible (Vf = 0). What is the value of V3(10s) – V4(10s)? Vi=4sin(2∏t) RC= 0.1s Homework Equations i (over...
  17. C

    Possible resistances using 3 resistors?

    Homework Statement You have 3 resistors 1000ohms each. List all the resistances you can achieve using this set. Homework Equations R in series = R1 + R2 + R3...etc 1/R in parallel = 1/R1 + 1/R2 + 1/R3...etc The Attempt at a Solution If they are all in series you have...
  18. D

    Resistors and Capacitors: Power Analysis

    Homework Statement Show that all the average power delivered to the the circuit winds up in the resistor. Do this by computing the value of V(R)^2/R. What is that power, in watts, for a series circuit of a 1uF capacitor and a 1.0k resistor placed across the 110 volt (rms). 60Hz power line...
  19. N

    Equivalent Resistance of Cube of Resistors: A to B

    Homework Statement Here is a cube of resistors with each resistance of value "R".Find the equivalent resistance between A and B. Homework Equations The Attempt at a Solution My book says the equivalent circuit of the cube is : But i don't think it is correct.They have made parallel...
  20. J

    Are these two resistors in Parallel?

    Say I have a circuit that looks like this: ..._______ B___|_|_|_|___ A The red and green lines are resistors. The black lines are wires. Assume a connection between any component line that is at a right angle to any other line, and a current source applied to points A and B.My question is...
  21. D

    Engineering Finding a voltage in a circuit with only resistors and current sources

    Homework Statement Find V0 in the circuit. Homework Equations Kirchhoff's Current Law: All currents entering a node must sum to zero. Kirchhoff's Voltage Law: All voltages around a loop must sum to zero. The Attempt at a Solution So far, I have taken the top of the center branch...
  22. Mechatron

    Op-amp output: resistors in parallel

    In the inverting operational amplifier circuit I've drawn below I am trying to calculate the output voltage and the voltage at the blue spot. The resistors are of the magnitude of several K ohm. I have done the following: Uout = Rf * (I1+I2+I3) = Rf * (U1/R1 + U2/R2 + U3/R3) The voltage Ux...
  23. C

    Help with circuits - resistors in parallel and in series

    Homework Statement http://imgur.com/iTHbpTv This picture contains the circuit drawn out, and all the provided numbers. It also includes some of my work. Homework Equations I=V/R P=I*R The Attempt at a Solution So I attempted to reduce it down to one resistor & one battery (26V...
  24. kandrew

    Resistors - connected in series or in parallel

    Resistors -- connected in series or in parallel Homework Statement The problem is asking for the currents, but I have a question about the resistors. I've been having trouble determining whether resistors are connected in series or in parallel. I've already looked at another thread in this...
  25. A

    Are these resistors in series or parallel?

    Homework Statement Ignore the wires that go out of the image. Homework Equations The Attempt at a Solution At first I thought they were in series because they're all lined up. But why can't the 4 kilo-ohm resistor and 12 kilo-ohm resistor be in parallel with the 6 kilo-ohm...
  26. Y

    Circuit Problem involving resistors and a switch

    Homework Statement When switch S in the figure below is open, the voltmeter V of the battery reads 3.68 V. When the switch is closed, the voltmeter reading drops to 3.50 V, and the ammeter A reads 1.80 A. Assume that the two meters are ideal, so they don't affect the circuit. Find the emf...
  27. Z

    Finding the values of resistors

    Homework Statement In the problem i have to find the values of resistors using voltage divider, and use KVL to determine the currents. Homework Equations Vi= [Ri / (R1+R2+...+Rn)] * Vs 1/Rtotal = 1/R1 + 1/R2 + ... + 1/Rn Ʃrise + Ʃdrop = 0 The Attempt at a Solution In order...
  28. M

    Understanding Resistors in Series and Parallel Circuits

    Homework Statement Here are the two problems I'm working with. We have to figure out the current and voltage for all components in the circuit. Sorry for the image, I wasn't sure how else to present the circuit on here.Homework Equations Ohm's law: V=IRThe Attempt at a Solution I actually...
  29. Y

    Electrical Energy Dissipation Across Resistors

    Homework Statement (image attached) A). What is the total rate at which electrical energy is dissipated in the 5.0−Ω resistor? B). What is the total rate at which electrical energy is dissipated in the 9.0−Ω resistor? C). What is the power output of the 16.0-V battery? D). At what rate...
  30. PsychonautQQ

    Variable Resistors in a Voltage Divider

    My textbook says that in a voltage divider (voltage source Vin, then a resistor, then another path that leads to Vout, Resistor two, Ground, that it is a bad idea to use variable resistors for BOTH of the resistors (but it is okay if you just do one or the other). Does anybody know why?
  31. B

    How to Calculate Equivalent Resistance with Kirchhoff's Laws?

    okay i have this somekind of a paradox in the circuit below voltage around R0 and R2 is supposed to be equal now if it is equal , wouldn't that mean that the current will not pass through the middle vertical wire ? and if it doesn't then this means that the resistors are now connected in...
  32. B

    Simple circuit - parallel resistors

    Simple circuit -- parallel resistors Homework Statement i am asked to find two or more resistors having the same voltage across their terminals , the answer is R2 and R0 , but i want to know why , note that there are no known values(they might or might not be equal i have no idea ) for R nor...
  33. G

    Circuit Problem with diodes and resistors with sine wave input

    Homework Statement Sketch Vo for the network shown (see attachment) and determine the dc voltage available. Homework Equations The Attempt at a Solution Vi is a sine like wave with amplitude of 100 V and goes on for one period. When Vi is positive, the diode on the right goes...
  34. H

    Equivalent Resistance - Resistors Intertwined

    Homework Statement Find the equivalent resistance between terminals a and b Homework Equations Series: Req = summation of resistors Parallel 1/Req = summation of 1/resistances The Attempt at a Solution So I figured out the easy ones, and so I'm here at the moment...
  35. W

    Calculating Charge and Current in a Resistor Circuit

    1. At time t = 0, a 23 ohms resistor is linked to a 4.4V battery. How much charge has gone through the resistor after 5 seconds? 2. Q = CΔV ΔV = IR 3. ΔV = IR I = ΔV/R = 4.4/24 A. I'm not sure what to do next.
  36. S

    Why are these resistors present in these schematics?

    The images represents circuits interfaced with an Arduino microcontroller. The first image is a controller circuit for running a piezo buzzer. I understand the application of the transistor here, but am not sure why the resistor is present in parallel with the speaker. The second...
  37. H

    Resistors in Series vs Parallel

    I am confused how I would add certain resistors, like the ones in the attached picture (sorry it's a bad picture). If I add the first two resistors as if they were in parallel (as they are), couldn't I then add that equivalent resistance to resistor 3 as if they were in series, since the...
  38. A

    Potential Differences and Currents in a Diamond Circuit

    Homework Statement In the figure ε = 15.1 V, R1 = 1560 Ω, R2 = 2130 Ω, and R3 = 4210 Ω. What are the potential differences (in V) (a) VA - VB, (b) VB - VC, (c) VC - VD, and (d) VA - VC? The figure consists of single ideal batter connecting to a diamond shape circuit ABCD. Going clockwise...
  39. 3

    What is the current relationship between resistors in parallel?

    Homework Statement I have a circuit with two resistors in series that are in parallel to another resistor. Each resistor is 5Ω. The total current running through the series is 4amps. I need to find the current in the single resistor that is in parallel. What is the relationship among these...
  40. P

    Multi-loop RC circuit, 2 batteries, 7 resistors, 1 capacitor

    Homework Statement For the multi-loop circuit as shown, assuming the capacitor is initially uncharged, find the currents in each of the resistors at t=0 after the switches are closed. So I believe there are 8 unknowns really because of the 8th branch with the capacitor. If you look at the...
  41. P

    What Are the Uses of RC Filters in Advanced Circuits?

    I don't understand why we use resistors at all. I've read that they cause a voltage drop and decrease the flow of electrons (current). Why is this useful? If we want to decrease the current, why not just lower the voltage? Don't resistors just waste energy?
  42. M

    Finding Current in Resistors

    Homework Statement What is the Current at the 1.1Ω resistor? http://imgur.com/VZzGoK8 Homework Equations V=IR The Attempt at a Solution So far I have found that the Req=5.775Ω The First Branch which contains 1.1Ω, 4.5Ω, and 10Ω has a resistance of 4.203Ω The upper Branch has...
  43. MarkFL

    MHB Ahmed's Calculus Parallel Resistors Q: Rate of Change Help

    Here is the question: Here is a link to the question: Calculus Parallel Resistors Question Help? - Yahoo! Answers I have posted a link there to this topic so the OP can find my response.
  44. E

    Resistors in parallel and series

    Homework Statement If an ohmmeter is connected between points and in each of the circuits shown in the figure . For the circuit a) what will it read? For the circuit b) what will it read? http://s3.amazonaws.com/answer-board-image/b299a065-5dff-4564-82e0-d1db1c9c2c88.jpeg Homework...
  45. M

    Combining Resistors and Capacitors

    Homework Statement This is like related to a homework problem, but I'm just curious: If we have two capacitors and two resistors in series, the overall capacitance and resistance does not change regardless of the order, right? Likewise, if they were in parallel (like a resistor + capacitor...
  46. F

    Solving Resistors in Series: 1.50 V Battery

    Homework Statement Three silver wires of equal length are connected in series with a 1.50 V battery. Their cross-sectional areas are 1.00, 5.00 and 10.0 cm2. (a) What is the potential difference across the narrowest wire? (b) The medium wire? (c) The widest wire? Homework Equations V= IR...
  47. R

    Not understanding pull-down resistors and why they work

    I'm understanding that their purpose is to keep the pin connected to a stable potential (the ground), thus giving it a stable LOW voltage reading when the switch is not closed, but wouldn't the electric noise still affect the voltage reading, since the point at the switch closest to the pin is...
  48. O

    Electrodynamics- combination of resistors

    Homework Statement What is the compensative system of this combination of resistors? http://img545.imageshack.us/img545/6610/circuitoi.jpg
  49. M

    How Does Voltage Drop Across a Resistor?

    Hello, I am having conceptual difficulties trying to understand how voltage is dropped across a resistor. The whole idea of it is confusing to me, where does this voltage go? Could it be explained in terms of point charges and electric fields, which is how I am able to visualize potential...
  50. B

    Voltage Across Resistors In Parallel

    Homework Statement Consider the circuit shown in the figure below. (R = 31.0 Ω.) (a) Find the current in the 31.0 Ω resistor. (b) Find the potential difference between points a and b. Homework Equations The Attempt at a Solution I am reading the solution of this problem...
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