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. A

    Help with resistors / Amateur Project

    Ok, just a warning... I'm an amateur engineer... I do things as a hobby (computer programmer by trade) Anyways, Here's what I'm doing: I'm trying to mod a guitar cabinet with LED lights that pulse with the music. I want to power it from the signal that comes into the speakers from the power...
  2. M

    Resistors & Heat: Quick Explanation Needed

    I'm doing coursework and i know it's dumb but i just can't remember how heat is supposed to affect resistors *heh* If someone could give me a quick explanation, it's not for the main part of the coursework, it's just a factor i have to controll in another experiment, but i can't remember why i...
  3. M

    Can You Solve This Circuit Using Kirchhoff's Laws?

    Identify the number and location of each of the items below. Assume that the resistances and source voltage are known. Use the gray highlighted letters. Identify voltage drops across resistor Ri as Vi. - How many nodes are there in this circuit? Where...
  4. S

    Resistor Combination: Current and Potential Difference Calculation

    Hello, I have a tricky problem with resistors combination. please check this url - http://www.disruptedstreets.com/physics.png Can anybody help me with this? Thanks The Question is - Calculate the Current at Point X and potential difference between points A and B.
  5. J

    Why Do We Need Resistors in Every Electronic Circuit?

    Why do we need resistors in every electronic circuit?
  6. P

    So, if Jimmy adds a resistor in parallel to a circuit with two other resistors

    So, if Jimmy adds a resistor in parallel to a circuit with two other resistors... Homework Statement wouldn't the resistance decrease? Homework Equations The Attempt at a Solution
  7. F

    Voltage in Series Circuits: Battery vs. Resistors

    Homework Statement in a series circuit, how is the voltage supplied to the circuit by the battery related to the voltages across the resistors in the circuit? Homework Equations The Attempt at a Solution
  8. K

    Calculating the resistors value?

    Calculate the value of the resistor using the following information: Vs=9volts, Vled=3volts, and Iled=10mA I'm assuming that it's just Ohm's Law R=V/I, but I don't know which of the two voltages I use, though I think its the Vs...but I don't know what the 's' stands for either. this...
  9. L

    Calculate the Current, Lost Volt and P.d across parallel resistors?

    Homework Statement http://img508.imageshack.us/img508/9121/10052008ei3.png (a) Calculate the Current across parallel resistors. (b) Calculate the lost volt across parallel resistors. (c) Calculate the potential difference across parallel resistors. Homework Equations I = \frac{V}{R}...
  10. T

    Resistors with Memory: Exploring AI Benefits & Uses

    Recently I heard someone mentioning a new invention, a kind of resistor with memory which was the missing link in artificial intelligence. A kind of analog computer if you will. The resistor somehow remembers in what state it has been in. I was very interested in what he said but I didn't...
  11. B

    Are the 10 ohm and 20 ohm resistors in this circuit truly parallel?

    So there is a circuit in my physics book which looks like [img=http://img177.imageshack.us/img177/4127/circuitcz2.th.gif] The problem asks for the current in the interconnecting wire between the 2 wires with the 2 resistors. I solved this using loop rules, but the book shows a shortcut by...
  12. C

    Circuits with parallel resistors

    Homework Statement 1) A circuit contains a 10V battery and three resistors in parallel. The resistors have values R1=10ohm, R2=40ohm, R3=50ohm. What is the voltage across each resistor? 2)This time, the 3 resistors in parallel have values R1=10ohm, R2=20ohm, R3=500ohm. The current flowing...
  13. S

    Why do resistors in series receive the same current

    Helllo guys, I was wandering why was this the case. If there were 3 resistors (Let's say 100ohms,200ohms,300ohms) in this seriec how can they receive the same current if resistance is inversly proportional to current. Shouldn't the 300 ohms one receive the least current. I thought resistors...
  14. A

    Applying Kirchoff's Law in an R-L circuit with parallel resistors

    http://img296.imageshack.us/img296/6961/circuithk7.jpg Assume that the switch has been closed a long time. 1.) Find the current through the inductor before the switch is opened. 2.) Find the voltage in the right resistor before the switch is opened. 3.) Find the current in the right...
  15. T

    Curious problem with resistors

    We have an infinite net of regular hexagons. Each side of hexagons has a resistance R. What is the resistance between two opposite vertexes of hexagon(s)?
  16. V

    Finding the currents of four resistors in a circuit.

    Homework Statement \epsilonbatt = 12V Find the following currents. The current I1 through the resistor of resistance R1 = 15.0 ohms. The current I2 through the resistor of resistance R2 = 45.0 ohms. The current I3 through the resistor of resistance R3 = 25.0 ohms. The current I4 through the...
  17. S

    Find the Min. Series Resistors for 9V & 0.25W

    Homework Statement A 47 resistor can dissipate up to 0.25-W of power without burning up. What is the smallest number of such resistors that can be connected in series across a 9.0-V battery without anyone of them burning up> Homework Equations V=IR P=IV The Attempt at a Solution I...
  18. M

    Find Ratio of Resistors R_1/R_2

    Homework Statement Two resistors of resistances R_1 and R_2, with R_2 > R_1, are connected to a voltage source with voltage V_0. When the resistors are connected in series, the current is I_s. When the resistors are connected in parallel, the current I_p from the source is equal to 10 I_s...
  19. A

    Resistors become insulators at some high temp.

    Every conductor or insulator becomes/is believed to become perfectly conducting at o kelvin Similarly every resistor should also have some upper limit i.e. it should become insulator at some very high temperature? Is it so? Please explain...
  20. 7

    Circuit with resistors in series and two power supplies

    Homework Statement There is a current of 0.25 A in the circuit of the figure What is the value of the resistance R? Homework Equations V = IR The Attempt at a Solution since the circuit is in series: V = 6+ 12 = 18V Req = R + 6 + 12 V = IReq Req = 18/0.25 = 72...
  21. tony873004

    Series and parallel resistors

    In the circuit shown, find the current in each resistor and the values of the potential at points A, B, and C. First I computed the combined resistance of the parallel resistors and got 4.54 kOhms. Then I added this to 10.5 to get 15.04 kOhms total resistance. So from Ohm's law, the...
  22. E

    Help with mosfet and resistors

    Hi I am trying to figure out how to determine the size of the resistors I need to put in line of the gate wire to turn on and off the mosfet in a circuit for an airsoft gun I have several mosfets laying around the 1 I want to use is a 50a 100v that said what size resistors do I need to put in...
  23. V

    Kirchhoff's Laws and current through resistors

    Question: The diagram below shows a circuit where; R1 = 5.00 Ω, R2 = 6.00 Ω, R3 = 1.00 Ω, V1 = 4.500 V, V2 = 20.00 V, and V3 = 6.00 V. (In solving the problems that follow, initially pick the current directions as shown. If the actual current turns out to be in the opposite direction, then...
  24. F

    Calculating Current Through Resistors in Loop Circuit

    Homework Statement Find the current through each resistor using the rules for series and parallel resistors and kirchhoff's rules there is a loop circut with three resistors in parallel, two on top and one on bottom, then one more in series outside of it. It's all attached to a 15 volt cell...
  25. M

    Potentiometer Use of Resistors

    Homework Statement I am uncertain how to provide a schematic, so I will ask a general question. Why would it be beneficial to use a larger resistor in a circuit using a potentiometer? Homework Equations The Attempt at a Solution
  26. F

    Reducing Equivalent Resistors and Capacitors

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  27. S

    Resistors in Series: Why Don't Electrons Use All Energy?

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  28. S

    What are the calculations for resistors in parallel?

    Homework Statement In the circuit shown in the figure, the rate at which R1 is dissipating electrical energy is 20.0 W. A) Find R1 B) Find R2 C) Find emf of battery D) Find current through R2 E) Find current through 10 ohm resistor. F) Find total electrical power consumption of the...
  29. X

    2 resistors connected in parallel. same two in series what is the current?

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  30. D

    Pd across resistors, can u explain the following?

    In a circuit that has a 12volt power supply and two 2- ohm resistors, R1 and R2, in series, the pd across each resistor is obviously 6v. If a 3rd resistor (also 2-ohm)R3, is placed in parallel across R2 then the pd across them changes to the following: R1=8v...
  31. S

    Find R1 & R2 for Vo in 4-8V Range in Figure

    Given the network in the Figure, we wish to obtain a voltage of 4 V ≤ Vo ≤ 8 V across the full range of the pot. Determine the values of (a) R1 and (b) R2. I'm quite confused as to what it means by "the full range of the pot." And I'm not quite sure how to approach this problem. Can anyone...
  32. I

    Calculating voltage across resistors

    Hi all, I am looking for a formula to work out the following- 500v---/\/\/\/\/---X---/\/\/\/\/---0v 1megohm 10kohm what is X? cheers
  33. W

    Calculating Current in a Circuit

    Homework Statement you measure a 20v potential difference across a 5 ohm resistor. what is the current? The Attempt at a Solution 20 v/5 ohms = 4 v is this correct? thanks.
  34. K

    Engineering Resistors in a 555 Timer Circuit

    I was using a 555 timer circuit to generate a tone the frequency of roughly 256 Hz with resistors of 22 and 270 Ohms and a capacitor of 10 uF but I was advised not to by my teacher and wasn't able to ask the reason why. Can someone kind of brief me on this since my teacher is away tomorrow and...
  35. S

    What is the solution for the total resistance of the infinite ladder network?

    Homework Statement Find the total resistance (each R = 1 ohm) of the infinite ladder network that looks something like this: !--------!------R-----!------R----!------R-----!----- etc ! ! ! ! ! V R R R R ...
  36. D

    How Do You Calculate Resistance, Current, and Power in Parallel Circuits?

    1. Ten 110-ohm lamps are connected in parallel to a 110-V house line. A) What is the combined resistance of the ten lamps? B) What current flows in the line when all ten lamps are operating? C) What power is then being supplied to the circuit by the line? I just wanted to have someone check...
  37. R

    Calculating the Rate of Change for Parallel Resistors

    If two resistors with resistances and are connected in parallel, as in the figure, then the total resistance R measured in ohms , is given by 1/R=1/R1+1/R2. If and are increasing at rates of .6 and .7 respectively, how fast is R changing when R1=80 and R2=100? so i take the derivative of...
  38. S

    What is the Resistance of Resistor X?

    Homework Statement For the resistor network shown in the figure, the ohmmeter reads 20.2 ohm. What is the resistance of the resistor X? Homework Equations See below. The Attempt at a Solution I’m uncertain if I tackled the system correctly, so please guide me on any...
  39. E

    Resistors problem. , thanks

    Hi, I am having a bit of trouble solving for an unknown current. Can anyone help me out, thanks. The resistor R in Fig18.56 dissipates 11 W of power. Determine 2 possible values of R (V= 76 V). My attempt so far, 1st loop: 35I-35I1=76 2nd loop: I=[(70/30)+(R/30)]I1 I plugged...
  40. V

    CIRCUIT ANALYSIS: Non-Ideal OpAmp with 2 resistors - Find Thevenin Equivalent

    Homework Statement There is a non-inverting op-amp below. http://img291.imageshack.us/img291/8242/chapter5lastproblemea1.jpg The op-amp is NOT ideal. We assume that R_i\,=\,\infty, R_0\,>\,0 and A is finite. Find the general Thevenin equivalent circuit seen at the terminals...
  41. V

    CIRCUIT ANALYSIS: 8 Resistors, 1 IVS, 1 Differential Op-Amp - Find Vo

    Homework Statement The circuit below is a differential amplifier driven by a bridge, find V_0. http://img476.imageshack.us/img476/8827/chapter5problem48fi2.jpg Homework Equations KCL, v = i R, Ideal Op-Amp relationshipsThe Attempt at a Solution I added 4 voltage markers...
  42. R

    Engineering Simplyfing Parallel/Series Resistors in a Circuit

    Homework Statement http://img463.imageshack.us/img463/997/screenshot01mu1.jpg Homework Equations V = IR Rseries = R1 + R2 + ... + Rn Rparallel = (1/R1 + 1/R2 + ... + 1/Rn)^-1 The Attempt at a Solution I simplified the circuit, to find I = 3mA. What I did was this (in order starting from...
  43. W

    Electrical heater using resistors

    Hi people is my first time posting in this forum... Great Forum¡¡¡ Every Sunday I work selling breakfast food and I got the same problem of all. Food getting cold, so I want to build a heater to maintain the food warn, just to keep it warn for the people be satified of my business...
  44. V

    Engineering CIRCUIT ANALYSIS: 3 Resistors, 3 Voltage Src, 1 Current Src - Find v1, v2, v3

    Homework Statement Find the node voltages V_1 through V_3 in the circuit below. http://img413.imageshack.us/img413/2240/chapter3problem328an.jpg Homework Equations KCL, KVL, V = i R, super-nodeThe Attempt at a Solution I added 5 currents and 2 KVL loops...
  45. V

    Engineering CIRCUIT ANALYSIS: 7 resistors, 2 Indep. Volt Source, V.C.C.S, V.C.V.S. - find I

    Homework Statement For the circuit below find I_1 and I_2: http://img155.imageshack.us/img155/8330/chapter2problem84ro6.jpg Homework Equations KVL KCL Ohm's Law The Attempt at a Solution I tried the problem many times, but I always get crazy answers. It seems that every...
  46. V

    Engineering CIRCUIT ANALYSIS: 2 resistors, Indep. Current Source, V.C.C.S - find v0

    Homework Statement Find v_0 in the circuit below and the power dissipated by the controlled source. http://img291.imageshack.us/img291/5479/chapter2problem22wy5.jpg Homework Equations KCL v\,=\,i\,RThe Attempt at a Solution KCL: i\,=\,2\,v_0\,+\,10\,A v_o\,=\,i\,R...
  47. N

    Current in resistors in series

    Problem/Question I am trying to understand why the current in resistors that are wired in series is the same. This makes no sense to me. Attempts at answering I will state everything I hold to be true, my entire reasoning process. So if at any point I am mistaken please correct me...
  48. A

    Using Series Resistors for Audio Sources: Is Jumpering Channels Safe?

    My understanding of a passive summing mixer is to use series resistors to limit the voltage from multiple sources so as to not over drive the destination? If you are combining two audio channels say from a VCR and jumper the left and right channel will this have serious reprocutions for the...
  49. H

    Calculate Voltage & Power in Series Circuit w/ 3 Resistors

    Three resistors are connected in series across a battery. The value of each resistance and its maximum power rating are as follows: 4.7 ohms and 17.7 W, 23.1ohms and 13.9 W, and 12.8ohms and 12.9 W. (a) What is the greatest voltage that the battery can have without one of the resistors burning...
  50. V

    CIRCUITS: Three resistors, two Indep. Voltage sources, one Indep. Current source

    Find I in the circuit using the superposition principle: My work so far: I\,=\,I_1\,+\,I_2\,+\,I_3 This reduces down to: 16\,V\,=\,I_1\,(8\Omega) I_1\,=\,\frac{16\,V}{8\Omega}\,=\,2\,A This reduces down to: I_2\,=\,-\frac{12\,V}{8\Omega}\,=\,-\frac{3}{2}...
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