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.

View More On Wikipedia.org
Recent contents Top users
  1. A

    Using a 2 kV Power Supply Safely: Reducing Current & Bleeder Resistors

    Hello all. If I was to create a circuit with a 2 kV power supply, how would I reduce the current so that if I were to accidentally become part of the circuit, I would be in no danger? Another question: Does a bleeder resistor help? Thanks.
  2. Q

    Voltage across resistors in RC circuit

    Homework Statement Calculate the voltage, current, and power across the two resistors for every second of run 1 in the RC circuit. The RC Circuit: The settings of the circuit: The Graph. The capacitor is charged until it reaches 5.0 V and then discharged until it reaches 1.0 V. This...
  3. F

    Kirchoff's Law - Wire in parallel with light bulb

    Homework Statement If you measure the resistance of the three lightbulbs (independently) and get the following values. What is the equivalent total resistance of the circuit, and it’s uncertainty. R_1 = (50 \pm 7) \Omega, \ \ R_2 = (720 \pm 30) \Omega, \ \ R_3 = 140 \pm 20) \Omega Now you...
  4. brainbaby

    Making the sum of 2 resistors independent of 1 of them

    I am really not sure about this ... I may be generalizing it ...but anyway... suppose we have two resistors in series...connected by ofcourse a voltage source...and a certain amount of total current is flowing through the whole circuit.. now if we want to make the total current totally...
  5. N

    Determining current from ammeter

    Homework Statement The ammeter reads 5.0A. Find I1, I2, and ε Homework Equations ΔV=IR The Attempt at a Solution I've never dealt with ammeters before so I'm very confused. To start, I tried breaking this into loops, and then used Kirchhoff's Law. I started with the left side, since I...
  6. W

    Circuit Components-Variable resistors

    Homework Statement As contact point Y moves to X, the lamps becomes brighter. Why is this so? Homework Equations R=p (length/Area) I=V/RThe Attempt at a Solution As Y moves closer to X, length of wire decreases, hence resistance decreases and brightness of lamp increases. I am not clear of...
  7. T

    Resistors in parallel with a capacitor, total resistance?

    Hello, I am not quite sure how to work out the before and after charging values for resistance and current. This is the circuit I am working with: So, when there is no voltage then the capacitor can be technically not considered as part of the circuit. So for the resistors, would R = 1/R1...
  8. brainbaby

    Requirement of emitter resistors in current mirror circuit

    In a current mirror circuit ..presence of an emitter resistor (R1 and R2) increases the output resistance which minimises harms of early effect...how? why its advantageous to have a high output resistance in current sources/current mirror circuits?
  9. A

    Solving Resistor Circuits: Find Currents in R & 10Ω Resistors

    Homework Statement The resistor R in the above figure has a resistance of 19.1 Ω. a. Find the current in the resistor R. b. Find the current in the 10-Ω resistor. 2. Homework Equations Kirchhoff's Laws (Junction Rule and Loop Rule) V=IR The Attempt at a Solution I figured out part a (I...
  10. GoldWing

    How Do You Calculate Net Resistance in a Triangular Network?

    Homework Statement Assuming R = R' in the network shown above, determine the net resistance between the points a and c. Express your answer as a number times R. b. Assuming R = R', determine the net resistance between the points a and b. c. Now suppose R' = 2.5R, and find the net resistance...
  11. M

    How do electrons know that there are other resistors?

    If there is only one resistor, the voltage drop is equal to the potential of the positive terminal. The voltage drop across more than one resistor is directly proportional to the value of each resistor. But the total drop in potential difference must be equal to the potential of the positive...
  12. A

    Combining Resistors: Determine Net Resistance b/w a & c/b

    Homework Statement Assuming R = R' in the network shown above, determine the net resistance between the points a and c. Express your answer as a number times R. b. Assuming R = R', determine the net resistance between the points a and b. c. Now suppose R' = 2.5R, and find the net resistance...
  13. A

    Finding Maximum Voltage of Resistors

    Homework Statement A 2.44-kΩ and a 4.92-kΩ resistor are connected in parallel; this combination is connected in series with a 1.12-kΩ resistor. If each resistor is rated at 1/2 W, what is the maximum voltage that can be applied across the whole network? Homework Equations P=V^2/Req V=I*R...
  14. CAH

    Calculating Resistance of Y with X & Variable Resistor

    I've got two resistors in parallel (X and Y) and a variable resistor, ammeter and voltmeter. SEE PHOTO! I've calculated the value of X by measuring V and I when the switch is open. I can close the switch and measure V and I but how do I calculate the resistance of Y? I know 1/x + 1/y = 1/R...
  15. E

    Can You Solve This Infinite Grid of Resistors Problem?

    Could you solve this?
  16. B. Vane

    RCL Circuit: 2 Resistors, 1 Capacitor, 2 Inductors

    Homework Statement NOTE: Image uploaded with thread shows problem in clearest possible form. V = (45v)sin(80[pi] t) Resistors 1 and 2 = 50 Ohms Inductor 1 = 20 mH Inductor 2 = 2.5 mH Capacitor = 50 uF a) Find the power dissipated by each resistor. b) At what frequency will both resistors...
  17. X

    Question about resistors (parallel and series)

    Here is a picture of a circuit: I have two questions: (1) Are all resistors connected in one of two ways? I.e., resistors can be connected in parallel and in series, but is it possible for them to be connected as NOT parllel and NOT series? For instance, the two circled resistors don't seem...
  18. J

    Why do resistors always cause a voltage drop equal to the voltage applied?

    Consider a wire connected to a battery. Now,potential is analogous to the energy of the particles.And potential in a resistor drops because of the friction inside the resistor(considering there is no friction along the wire and outside the resistor).So the friction determines how much energy is...
  19. D

    Adding resistors to a differentiating op-amp?

    I know how to derive the expression Vout = -CR*d(Vin)/dt for a circuit differentiator that consists of a capacitor and a resistor, how I can understand the attached circuit, which is part of practice exercise for my class. Why do we need to add R2 and R3? When I run the simulation Vout =...
  20. F

    Ammeter from parallel to series, current change

    Homework Statement In the circuit shown, a student mistakenly connects a perfect ammeter(i.e. One of negligible resistance), in parallel with one of two identical resistors. The ammeter reads 0.40A. What would the reading have been if he had correctly connected the ammeter in series with the...
  21. G

    Unknown value of added resistor in parallel

    Homework Statement Picture provided. The current going through the resistor R1 in the figure does not change whether the two switches S1 and S2 are both open or both closed. The resistances are R1 = 14.00 Ω, R2 = 142.00 Ω, and R3 = 24.00 Ω. The voltage is V = 11 V. With this information, what...
  22. O

    How Do You Calculate Voltage Drop Across Multiple Resistors?

    Homework Statement Determine the voltage at each labelled point with respect to ground Homework Equations V*r1/(r1+r2) i*r1/(r1+r2) i=v/R The Attempt at a SolutionI'm doing a practice problem and I can't seem to get the right answer. I just want direction in the way to solve it, these are...
  23. L

    Finding the Unknown Resistance Value

    Homework Statement The current going through the resistor R1 in the figure does not change whether the two switches S1 and S2 are both open or both closed. The resistances are R1 = 70.00 Ω, R2 = 50.00 Ω, and R3 = 62.00 Ω. The voltage is V = 15 V. With this information, what is the value of...
  24. L

    Obtaining a maximum resistance given a set of resistors

    My gut instinct is that putting all the resistors in series will give max resistance, but I am not sure how to give a more rigorous either mathematical or just in words reasoning why. Or maybe I'm wrong! But it seems like the fraction introduced from parallel won't help In any case, assume all...
  25. jcoona

    Resistors Used in College Electrical Circuits Labs - Any Suggestions?

    I am taking an intro electrical circuits course which requires that I write extensive lab reports. I just completed a really simple lab about calculating resistance when configured in series and parallel, etc. In my intro I'm writing a short explanation about resistance, and resistors, and...
  26. S

    Calculate the equivalent resistance

    Homework Statement Ignore the internal resistance of the battery and assume it is merely a battery. Calculate the equivalent resistance of the circuit. Homework Equations 1/Req = 1/R + 1/R ... (parallel) Req = R + R ... (series) The Attempt at a Solution I know this is fairly simple but I...
  27. L

    How did we use the + and - ends of resistors in this problem

    Homework Statement https://6002x.mitx.mit.edu/static/circuits/ocwe1_1.png [/B] What happens when you click on this link? https://6002x.mitx.mit.edu/section/three-series-resistors-slow/ Exercise 1-1, Part 1, Detail Or this one https://6002x.mitx.mit.edu/courseware/ The original problem is...
  28. P

    Why capacitors and inductors affect the phase and resistors

    hello! why capacitors and inductors affect the phase of both current and voltage of a AC circuit and resistors don't? let's say we have an AC circuit with resistors only, then there is no change in the voltage and current as imposed from the voltage/current source, right? but what happens...
  29. C

    What is the correct way to analyze a circuit with resistors?

    Homework Statement [/B] R1 = 42 Ω R2 = 124 Ω R3 = 119 Ω R4 = 105 Ω Rx = ? I4 = O A Homework Equations R = IV V = V1 = V2 for parallel Resistors Iequiv = I1 +I2 for parallel Resistors Vequiv = V1+V2 for series Resistors Iequiv = I1= I2 for series Resistors The Attempt at a Solution I have...
  30. Steven Ellet

    Resistors: what will give me a constant voltage

    I would like to know what will give me a constant voltage no matter what the input is (within reason of course) Example: input 9 volts, output 1.5 volts; input 6 volts, output 1.5 volts; input 1 volt, output <1.5 volts.
  31. E

    Charge & Current in a Circuit: V, R, C, & t

    Homework Statement There is a circuit with a battery of voltage V and resistor R, then splits into two branches one with a capacitor C, and one with a resistor 2R. The answers for the questions can only depend on R, C, V, and t. When a switch only allows current to flow through the capacitor...
  32. minimario

    How to Distinguish Resistors in Series vs. in Parallel

    How do you tell if 2 resistors (or capacitors, etc.) are in parallel or in series? For example, calculate the resistance in the following circuits: How is the first circuit simplified, and what is an easy way to distinguish which resistors are in series, and which are in parallel? Thanks!
  33. 2

    Total rate at which electrical energy is dissipated by resistors

    Homework Statement A resistor with R1 = 25.0Ω is connected to a battery that has negligible internal resistance and electrical energy is dissipated by R1 at a rate of 36.0W. If a second resistor R2 = 15.0Ω is connected in series with R1, what is the total rate at which electrical energy is...
  34. zug

    Parallel Resistors (special cases formula)

    Homework Statement Problem: A car's rear window defroster uses 15 strips of resistive wire in a parallel arrangement. If the total resistance is 1.4 ohms, what is the resistance of one wire? Solution: rearrange formula to $$ R nR_{T} = (15)(1.4 \Omega) = 21 \Omega $$ Question: What is the...
  35. icesalmon

    Circuit with 3 batteries and 4 resistors

    Homework Statement The question pertains to the first problem from this link https://courses.physics.illinois.edu/phys212/sp2014/practice/practice.pl?exam2/fa10 They ask for the value of "I" in terms of V1, V2, R1, and R2. Homework Equations V = IR ∑Vi = 0 [/B] The Attempt at a Solution...
  36. C

    Power dissipation limit for a resistor

    I am confused about the concept of a power dissipation limit for a resistor. Basically for a resistor the product of the current through it and the potential across it should not exceed 0.25 watt otherwise it starts to heat up and act in a non-linear fashion. Is this value just a constant or is...
  37. C

    The current through an individual resistor

    The following circuit has been modeled using some modelling software (Micro-Cap 11). I was wondering why current is only shown at the source and not in R1, R_Unknown and R3. I know current is meant to be the same in series although I am confused by the effects of the resistors. (This is not a...
  38. R

    What is the current through each resistor in this circuit?

    Consider the circuit shown in the figure . Suppose the four resistors in this circuit have the values R1 = 12 , R2 = 6.0 , R3 = 7.3 , and R4 = 15 , and that the emf of the battery is E = 18V . (1) Find the current through each resistor using the rules for series and parallel resistors. Answer...
  39. K

    Problem solving for current in parallel resistors

    Homework Statement I am able to solve most of the DC circuit problems we're given, but I seem to be missing something conceptually when it comes to finding current that passes through individual resistors when they are in parallel. An example problem would be #10 at this link...
  40. icesalmon

    Voltage in Circuit with Two Batteries and Six Resistors

    Homework Statement A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18 V and V2 = 12 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 40 Ω, R2 = R6 = 156 Ω R3 = 69 Ω, and R4 = 113 Ω. The...
  41. G

    Finding Unknown Currents in a Two-battery Complex Circuit

    Homework Statement Look at the circuit given in figure 1. Solve for the three currents, I1,I2,I3. Homework Equations KVL: Sum of voltages in a closed loop equals zero KCL: Sum of currents entering a junction equals the sum of currents exiting a junction Ohm's Law: V=IR NOTE: Nodal analysis...
  42. davidbenari

    Internal resistence: chicken and egg misconcpetion

    I feel like have a chicken and egg type of problem regarding internal resistences because of the following problem: The voltage across a battery with internal resistence is given by the equation EMF-Ir=V Given the voltage across the battery then the voltage in the circuit is V=IR So, if I have...
  43. J

    Engineering Thevenin Equivalent for circuit with diagonal resistors

    Homework Statement Hi everyone! I'm trying to find the thevenin equivalent for part A of this circuit: http://imgur.com/4Jdg8w8 Homework EquationsThe Attempt at a Solution I first remove part B, that is, open circuit it entirely. Then I try to find Voc across the two terminals that are open. I...
  44. A

    Finding the Effective resistance of a tree of resistors

    1. A) Find the Effective resistance of a tree of resistors that bifurcates 3 times. B) Find the effective resistance of a tree of infinite resistors. (if the tree below went on to infinity) Homework Equations Ohm's Law The Attempt at a Solution I have no idea how to start this. There was no...
  45. C

    Calculating power of one of two resistors

    Homework Statement Two resistors R1 and R2 are connected in series to a battery supplying a voltage of ∆V as shown. How much power is dissipated by the resistor R2 in the form of heat? Use the following data: R1 = 10 Ω, R2 = 5 Ω, ∆V = 3 V http://tinypic.com/r/153tr91/8 2. Homework Equations...
  46. H

    Adding resistors in parallel - Current Change through resistors

    Homework Statement A resistor is added to a circuit in parallel.. How does the current through the pre-existing resistor change?Homework Equations V=IRThe Attempt at a Solution [/B] From one viewpoint, I understand, because no matter how many resistors you add to a circuit, the voltage across...
  47. B

    How to arrange given resistors in a given shape to meet target value?

    Homework Statement I have available resistors of 5 different values (10kΩ, 22kΩ, 47kΩ, 100kΩ and 220kΩ). How can I choose a combination of these resistors that will create a total resistance of 35kΩ in a U shape (using 5 resistors)? See attached picture of 'U' to get a clear picture of the...
  48. J

    Circuit Question Involving Resistors and Inductors

    Homework Statement For the circuit below, if L=2.0 H, emf=10 V, R1=10 ohms, R2= 20 ohms, what is the current through each component a) at the instant the switch is closed b)a long time after the switch is closed c) If after a long time the switch is reopened, what is the time constant...
  49. V

    Uncertainty error of resistors in parallel

    Homework Statement Find the Uncertainty of the Total Resistance of two (2) parallel-connected resistors: R1 = 2.2 kΩ ± 5\% \ ;\ R2 = 1.8 kΩ ± 20\%. Homework Equations We know that resistors in parallel are: \frac{1}{R_t}={\frac{1}{R_1±\delta_{R_1}}+\frac{1}{R_2±\delta_{R_2}}} This...
  50. Z

    Phantom Resistors: Solving Mysterious Readings

    hi guys I am attempting to solve a problem that has me scratching my head. I have a small connector PCB with one 8k resistor present. The connector is four way with the resistor terminals being the two inner pads. The outer two pads are short circuit together. I solder two wires on the...
Back
Top