Resistor Definition and 894 Threads

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. Cyrus

    Circuit Analysis: Voltage Across Resistor vs. Time

    Sorry, no picture my bad. Here is the circuit, everything is in PARALLEL, First its a 1mA source, then its a switch, then its a resistor of 10k-ohm then its a capacitor 1uF. Sorta like below: ---------------------------------- | ...| .... |.... | O...Switch ... R ... C |....|...
  2. T

    RMS Current in Circuit with Capacitor, Inductor, Resistor, AC Source

    Four circuit elements—a capacitor, an inductor, a resistor, and an AC source—are connected together in various ways. First the capacitor is connected to the source, and the rms current is found to be 25.1 mA. The capacitor is disconnected and discharged, and then connected in series with the...
  3. denian

    What are the closest standard resistor values to 175kOhm?

    if not, what resistance is the closest to 175kohm? tqvm.
  4. N

    Current Increase When Connecting Capacitor to Resistor

    I have conducted an experiment in school I have some problem with it . I connect a resistor 6600 ohm to a 6V direct current and I read the miliammeter and it show about 0.9 mA . But after I connect a capacitor 3300 F parallel to the resistor , the miliammeter increase to more than 1 mA.Why the...
  5. T

    Understanding the Relationship Between Inductors and Resistors in an AC Circuit

    v(rt) = 125mV cos (wt + 60) R=250 ohms L = 250mH find i(t) in the circuit there is a inductor in series wif the resistor the answers i(t)=0.5 cos (wt+60) may i know why is it the inductor not using to form z and then only divide by v(rt) ??why only the resistor??
  6. T

    How Do You Calculate Voltage Across Each Resistor in a Mixed Circuit?

    I have a 12V power source in a circuit and 4 resistors in a line and 1 on the side how do i find the voltage across each resistor?:confused:
  7. T

    Calculating Current and Power in Resistors: A Comprehensive Guide

    can any1 clue me into how u calculate the current through a resistor and the power absorbed by a resistor please!?
  8. K

    Finding Equivalent Resistance in Resistor Network - Can You Help?

    Can someone tell me where I'm going wrong here? I'm uploading a jpeg of the circuit, I'm supposed to find the equivalent resistance between A and B. To me, it looks like R5 and R6 are in parallel and forming Rp56. From there I'm assuming that Rp56 would be in parallel with R3 and then that...
  9. M

    Confused on how to find current also why is this resistor labled +/- not -/+

    Here is the diagram and work the answer booklet says: http://img69.imageshack.us/img69/2593/untitled1copy7wg.jpg Okay first question, If you loook on the image and look at the Current Source Is, the arrow shows its going up and to the left, so that means its going to go through the 2.5 OHM...
  10. M

    Confused on concept of finding voltage drop across a resistor

    Hello everyone I have a slight problem. I am confused on how you know what path current is going to travel and also what voltage sources your suppose to add up to a specific resistor. For example here is my picture, already solved: The directions where to find the value of ix, the orignal...
  11. M

    What is the rms potential difference across the resistor?

    Hello every9one I'm stuck on finding the first part: A series RLC circuit is driven by an alternating source at a frequency of 380 Hz and an emf amplitude of 90.0 V. The resistance is 20.0 , the capacitance is 12.1 µF, and the inductance is 24.2 mH. What is the rms potential difference...
  12. E

    Why would a circuit have a zero ohm resistor (3 black bands) in it?

    Why would a circuit have a zero ohm resistor (3 black bands) in it?
  13. A

    Engineering Voltage Across Resistor in Series Circuit: Impossible?

    for the question: the toal voltage across a string of seires resistors is 24V. If one of the resitors is open, how much voltage is there across it? How much is there across each of the good resitors? my problem: isn't it impossible to find which part is open in a series circuit without...
  14. A

    Engineering Resistor Failure: Is it Open or Short Circuit?

    The statement, "when a resistor fails, it will normally open." is true. But I don't understand: when a resistor fails, doesn't that mean that the resistor doesn't work? so doesn't that mean that resistance=0=short circuit?
  15. M

    Help with simple resistor problem

    SEE POST 4 I am having problems solving these resistor problems and was wondering if anyone could help. Really what I think my problem is is that i don't know what to do if there are series and parallel resistors on the same circuit For attachment three The resistance of the...
  16. recon

    Can you assist with solving an infinite resistor network problem?

    Could someone be so kind as to assist me in solving the following problem? I have had some basic knowledge of how the effect of multiple resistors add up in parallel in and in series, but I'm pretty much lost on how to solve this problem. Consider an infinite network of resistors of...
  17. E

    What happens when an LED is connected to a pull-up resistor circuit/switch?

    I am getting ready for my lab tomorrow and one of the questions is this: ok, here's what I think: since current flows from anode to cathode and in first case LED's anode is connected to the pull-up resistor, so there's current through it and it's going to light. In second case, wouldn't it...
  18. A

    Finding a temperature rise in a resistor. HELP

    I'm building an electric furnace using a coiled resistance heating element. The wire is a high temp alloy made for kilns and furnaces (Kanthal A-1 if you care.) Anyway... I can't find a way to calculate how hot the wire will get based on the current load and amount of wire. If the wire is too...
  19. S

    Load Resistor in a MOSFET amplifier

    Hi Guys! well! i have designed a mosfet amplifier. This amplifier uses only MOSFET in its operation along with an input signal and capactors and resistors and VDD. I want to ask u one thing. The amplifier which i have designed takes 0.1V of AC signal as an input and provides a gain of...
  20. F

    How Should Error Bars Be Placed in an Ohm's Law Lab Graph?

    Hey everyone. I am doing an Ohm's law lab where there is a variable source, a fixed resistor, a voltmeter across the resistor, and an ammeter in series with the resistor. The fixed resistor is an unknown value but has a tolerance of 5% You need to figure out its value by plotting...
  21. D

    What Is the Resistance of Each Resistor in a Modified Cube Circuit?

    Imagine a cube where all sides have a resistor, now remove one resistor from it and replace it with an ohmmeter, the ohmmeter reads 100ohms, calculate the resistance of each resistor. By the way each resistor is the same value. How do you go about doign this question?
  22. S

    Current in Circuit with Emf, Resistor & Capacitor

    If there is a circuit with--Emf -5V and one 5ohm resistor and one 20 F capacitor, what is the current of the circuit? Will there be any effects on current because of capacitor? :smile:
  23. C

    Capacitor and Variable resistor

    A controller on an electronic arcade game consists of a variable resistor connected across the plates of a 0.220\mu F capacitor. The capacitor is charged to 5.00V, then discharged through the resistor. The time for the potential difference across the plates to decrease to 0.800V is measured by a...
  24. D

    Troubleshooting 9V and 1 Ohm Resistor Connection

    Hi! I connect 9 volts to a 1 ohm resistor and thought I would get I = U/R = 9 A. But when I connect the ampmeter, I cannot read anything! Where is the problem?
  25. F

    Is current used up in a resistor or the voltage is used up?

    is current used up in a resistor or the voltage is used up?
  26. S

    How Do You Calculate Self-Inductance of a Resistor in an A.C. Circuit?

    does anybody know how to calculate the self-inductance of a resistor in a series A.C resistive capacitive circuit? (have values for supply voltage, R voltage, C voltage, current) any help at all would be much appreciated
  27. N

    Thermistors - Voltage across a resistor compared with temperature

    I have physics courseowkr due tomorrow on sensors. Mine is on thermistors. I have got results of voltage across a resistor and this is compared with temperature. I don't know what my results tell me though and so I can't really hand in the coursework. Does anyone know anything about thermistors...
  28. S

    How do I calculate the net resistance in a complex resistor circuit?

    I really confused by this circuit: http://myspace.homelinux.com:32123/circuit.jpg When calculating the net resistance from A to C, how do I know if any current goes through 2 and 7? If there was current going through them, I have clue how they would contribute to the total circuit. For the...
  29. C

    Calculating Current Through Resistor - Help Needed!

    Hi all, I need to find the current through a resistor knowing the # of electrons passing through it over a given time, t. Can someone help me out with this? I thought it was just I = #elec/time, but this cannot be right (i'm getting values along the lines of 1.5E19 Amps) Thanks, Brad
  30. L

    How Do You Calculate Current Through Each Resistor in a Mixed Circuit?

    if you have a circuit where there are resistors in parallel as well as in series how do you calculate the current through each individual resistor? I have found examples that explain it when they are all in series or all in parallel but i am very confused otherwise.
  31. M

    Resistance of n Resistors in Series & Parallel: Solve n,N & R

    Question 1: A group of n resistors each of resistance R, are connected in series. What is the total resistance?What is the total resistance if the resistors are connected in parallel? Questions 2: A series-parallel group of resistors each of resistance R, have n equal resistances in series...
  32. V

    Strange resistor voltage curve in an RC

    Hello, My data gravely perplexes me. I've set up a simple series RC circuit with an AC emf of 14V @ 20Hz. Resistor and capacitor values are 3.9E4 ohms and 4.7E-5 farads respectively. Ideally, the voltage across the resistor should be a simple sine curve, since this is basically an RLC series...
  33. P

    Calculating Delta T for a Resistor - Philip's Guide

    Lets say I'm given a 'specific heat, density, currenty density J, and the time that J exist, how can if find the the change in Temperature? My main problem is I don't know how to start the problem, a couple pointer in the right direction would be great. Thanks Philip
  34. M

    How to Calculate Energy Dissipated by a Resistor with Changing Current

    I have the solution to this problem, but I can't figure out how to solve it for the life of me. I'd appreciate any assistance: Image: http://www.cc.gatech.edu/~strobel/problem.gif The switch in the figure above has been in position 'a' for a very long time. It is suddenly flipped to...
  35. M

    What is the impedance across a resistor?

    hi, i want to ask, what is the impedance across a resisitor? isn't it just the value of the resistor? say i have a resistor of 50ohms, then its impedance is 50ohms, right?? thanks!
  36. A

    Star-Delta Circuit: Measuring Current with 6R Resistor

    http://floti.bell.ac.uk/principles/star%20delta/img008.gif sorry...i don't know how to post the pic here...juz want to know if 6R resistor is replaced by a galvanometer which has the internal resistance 6R,what will be the reading?
  37. J

    A circuit with capacitor and resistor

    A circuit with capacitor and resistor ! Dear all, it is a simple electric circuit include one capacitor and one resistor in parallel. about 25V is provided. Then i assume I1 cross the capacitor and I2 cross the resistor. Therefore, when a capacitor has a constant change, can i assume the I1...
  38. S

    Electric field inside a resistor

    A resistor (20 ohm) is made of a very thin piece of metal wire, length = 3mm and diameter = .1mm. Given that it has a potential of 8 volts and .4 amps of current running through it, what is the electric field inside the wire? I know there's no electrostatic equilibrium here, so I can't just...
  39. K

    I'm clueless. Oscilloscope as resistor

    I've thought and thought and thought about this, but I can't figure it out. How might I be able to estimate the apparent resistance of an oscilloscope? We're dealing with an oscilloscope connected to a circuit which uses a resistor and a capacitor. I think this question might have something to...
  40. A

    Smiple circuit with just one resistor

    In a smiple circuit with just one resistor, consider the current that flows. If you increase the resistance, less current flows. If you increase the supply voltage, the current increases. One book says that increasing voltage provides charge with the energy needed to get through the resistor...
  41. M

    Solving Resistor Problems 17, 26, & 27

    Problem 17. A(n) 5.2 ohm resistor, a(n) 9.2 ohm resistor, and a(n) 14 ohm resistor are connected in series with 6.0V battery. Determine the equivalent resistance for the circuit. Answer in units of ohms. Note: I don't know where to start. Problem 26. A resistor with an unknown...
  42. S

    Calculating V1 and R3 in a Parallel Circuit with Given Resistors and Currents

    Determine V1 and R3 if R1= 8ohms I1= 0.75A, R2=5 Ohms and I2=6A. Note that R2 and R3 are connected in parallel. Thank you.
  43. F

    How Does Current Divide in a Series Circuit with Different Resistors?

    what is the current through the 2 ohm resistor? what is the current through the 8 ohm resistor? 8 V ...! |... . empty space . . empty space . I . empty space . ...2 ohm Res... . empty space . . empty space 8 ohm Res . empty space . I_2 . empty space . ...! |... 16 V...
  44. E

    What is the solution for the honeycomb resistor problem?

    well i hope someone knows how to solve this problem... :smile: well you see in the picture that there is a honeycomd-like circuit...every line that comprises the honeycomb has a resistor with a resistance of R...meaning in a hexagon, there are six resistors... the question is to find the...
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