What is Resistor: Definition and 891 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. M

    NOOB QUESTION: What kind of resistor do I need?

    First off.. this is my first attempt playing with this kind of stuff.. please have a bit of patience with me :) I'm looking to make a costume out of LEDs for burningman.. bought a 1000 of them off ebay and when I connect them the 9V battery I'm guessing is too strong for it and burns the...
  2. P

    One Resistor, 9V Battery, and Ohm's Law: What is it Resisting?

    Hi, This may sound a little silly but I have a circuit with 1 resistor which is a 1k ohm resistor and is connected to a 9 Volt battery.I found the amps using ohm's law I = E/R which equals 9 amps.I have also used a multi-meter to see the resistance and I'm a bit confused a resistor is...
  3. Q

    How to find the current in the no resistor wire?

    I can't find the current in the following picture, please help me to find it and show the step, thanks.
  4. M

    Voltage across a load resistor in a Voltage Divider Circuit

    Homework Statement Show that V across Resistor Rkohms is: (11R) / (3.96 + 4R) V The circuit is a 5V cell in series with a 1.8k resistor. Following the 1.8k resistor are a 2.2k and Rk resistor in parallel with each other. The wires then rejoin and return to the cell.Current through the circuit...
  5. I

    Understanding Power Ratings on Resistor: Will 50V DC Harm It?

    I recently bought this resistor: http://www.radioshack.com/product/index.jsp?productId=12573233 I want to hook it up to about 50V DC, but I want to know if this would be harmful to the resistor. According to the description it can handle up to 800V, but its power rating is only 25W. This...
  6. P

    Energy dissipation in the resistor of a passive lowpass filter

    Hello everyone, this is my first post, and I hope I have put this in the right area. I am looking to understand something about the behavior of a low pass filter. When an alternating current is passed through a low pass filter, the higher the frequency, the lower the voltage output of the...
  7. N

    Confusion:collapsing 3 points with equal potential in a cubical resistor network

    Homework Statement The question is to find Equivalent resistance between opposite ends of a cubical resistor network . each resistor of resistance R . I am referring to this website here http://mathforum.org/library/drmath/view/65234.html I am halfway through it but I am stuck at a...
  8. T

    Current in a parallel resistor?

    Homework Statement The problem involves a battery of emf 10V [with no internal resistance] and a combination of resistors. Here is the diagram provided: A picture of the diagram can be found here: http://gyazo.com/7791710d0645de38cfab59f0ac4740ec (Couldn't get the image feature to...
  9. H

    Calculating Internal Resistor in a Series Battery Circuit

    Homework Statement Helping someone regarding this Qns: A Battery is formed by four 1.5 V identical cell in series. When a external resistor of 31 Ohm is connected across he battery, the current is 280 mA. Find the internal resistor of each cell. Can someone help to solve pls? Thank you...
  10. E

    Help Me Find Resistor Network Specs for My Circuit Board

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  11. F

    Attenuator resistor formulas ?

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  12. T

    A diode with a resistor in parallel and in series.

    I have a diode with a resistor in parallel(R2), but also diode resistor circuit has a resistor in series with it(R1). I have uploaded a drawing as well but I think it takes a bit of time for them to be authorised. The values of the circuit are Vs = 20v R1 = 3kΩ R2 = 470Ω Diode = Has a Volt drop...
  13. S

    Magnitude and phase angle of the resistor voltage

    the question is to find the magnitude and phase angle of the resistor voltage in the circuit below : http://img513.imageshack.us/img513/1035/ee204.jpg i want you guy's to check my solution please . thanks .
  14. W

    Calculating total resistance of a combination circuit with a diagonal resistor?

    I have been given this problem, I've simplified it down to a total resistance however I'm unsure on whether I have done it correctly. Any pointers would be nice, thanks. First of all I added the two resistors together in the top right as they are series. I then used that product with the...
  15. H

    Combining Series and Parallel Resistor Combinations

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  16. S

    Stuck on a single loop circuit, two emfs and resistor

    Homework Statement ε[1]=12v internal resistance[1]=.016Ω ε[2]=12v internal resistance[2]=.012Ω some unknown resistance 'R' in a stand alone resistor. a) what value of 'R' will make the terminal-to-terminal potential difference of one of the batteries zero? b) which battery would it be...
  17. S

    Ohmic Resistor modelling ?(Check my interpretation of question)

    http://dl.dropbox.com/u/33103477/Resistor.png For the first bit first I solved the equation \frac{dI}{dt}=\frac{U-RI}{L} I(t)=\frac{U-C_2e^{\frac{-t}{L}}}{R} Now I put in T(0)=0 to work out the constant and I got I(t)=\frac{U-Ue^{\frac{-t}{L}}}{R} Now here's the dodgy bit, I did...
  18. S

    Resistance Cube: Finding current through each resistor

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  19. P

    Serial Resistor solution to finding individual voltage not adding up

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  20. C

    Maximum current through resistor in a coil of wire with two resistors in parallel

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  21. B

    Understanding the Symmetry of the Resistor Cube Problem

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  22. T

    Low-pass filter with no inductance, and voltage output over a resistor

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  23. C

    Appropriate arrangement of light meter circuit with LDR and resistor question:

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  24. M

    Resistor & Ideal source network

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  25. S

    Cube R network resistor calculation

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  26. W

    What factors determine the maximum power a resistor can handle?

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  27. G

    Solving Star Resistor Configuration Problem

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  28. S

    [Quick] At what capacitance will the current in the resistor be a maximum?

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  29. C

    How Does Gate Resistance Rg Impact JFET Amplifier Performance?

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  30. B

    Calculate the power delivered to each resistor

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  31. K

    Capacitor & Resistor: Connecting in Parallel w/ Battery

    My physics teacher said the other day that, if you connect a capacitor and resistor in parallel with a battery, no current will go through the resistor, since the current doesn't like resistance and so will follow path of least resistance (to the capacitor). But then the next day, I think he...
  32. T

    How to Simplify Resistor Networks: Parallel and Series Connections

    Homework Statement Homework Equations Resistors in parallel and series The Attempt at a Solution I connected points which had the same potential. I'm not sure where to go from here tho.
  33. S

    Resistor - Capacitor - Resistor

    This should be a simple question. If you have a series circuit in the following order: emf, resistor1, capacitor, resistor2 Are both resistors in series during the charging interval considering that they both have the same current through them? That is, would a resistance of resistor1 +...
  34. M

    Why Does Replacing 3.0 Ω Resistor Affect Current Through 6.0 Ω?

    Question b. in paint doc. My answer is: Becuase they said the current in question a. through the 6.0 ohm resistor is 1.0 A I am going to say the only two that will change is resistor 7.0 Ω and the newly replaced 3.0 Ω resistor... I am saying the current through the 6.0 ohm resistor will not...
  35. J

    Find power when resistor, capacitor, and inductor are connected in a series

    Homework Statement When a resistor is connected by itself to an ac generator, the average power delivered to the resistor is 0.952 W. When a capacitor is added in series with the resistor, the power delivered is 0.477 W. When an inductor is added in series with the resistor (without the...
  36. D

    What Is the Correct Way to Calculate Resistance in Complex Resistor Networks?

    Homework Statement Hi guys, Im new here and I am working for the first time with with these applications. So, i have this resistor network https://www.physicsforums.com/attachment.php?attachmentid=44965&stc=1&d=1331497208 where R1=220 ohm and R2=330 ohm. I must find the electrical resistence...
  37. R

    Why does voltage drop to zero over a resistor?

    How I am currently imagining it: In a simple circuit with just a battery and resistor the voltage of the battery sets the electrons off through the circuit at some speed and that speed is proportional to the voltage. The electrons then encounter the resistor. From these forums my...
  38. F

    What is the voltage across a resistor in an electrical circuit?

    Homework Statement The voltage V(t) [in volts] across a resistor in an electrical circuit at a given time t [in seconds] is given by: sqrt of something to the power of pi ^ that's the example i got in my book. Its just got the square root symbol, a space, and then a pi in an exponential...
  39. H

    Energy dissipated through resistor

    Homework Statement The problem first asks to find potential difference across the capacitor after the switch has been closed a long time. Then it asks to determine the energy stored in a capacitor when the switch has been closed for a long time. I got both these answers right, with...
  40. H

    Calculate current in one resistor in RC circuit

    Homework Statement The capacitor is initially uncharged when the switch is closed for a long time. Calculate the current through R2. Then find the potential difference across R1, R2, and R3Homework Equations V=IR Iin=IoutThe Attempt at a Solution I first set up current going into top node (I1)...
  41. M

    What is the current through Resistor on RC circuit

    Homework Statement The diagram below depicts an RC-circuit where C = 1.70 μF, R1 = 18.0 Ω, R2 = 10.0 Ω, and V0 = 2.0 V. a.) What is the current through R1 immediately after the switch S is closed? b.) What is the current through R2 after the switch S has been closed for a very long time...
  42. S

    Resistor which reacts to moisture in soil or water.

    my friend and i are doing a DP lab, we are trying to find a resister which reacts to water/ moisture in soil. a resistor that is directly proportional to the moisture in the soil thank you.
  43. W

    Engineering Kirchoff's Tension Law, resistor circuit.

    Homework Statement Find I1, I2, I3, I6 (intensities at R1, R2, R3 and R6) using Kirchoff's Tension Law. R1 = 1/3 Ohm, R2 = 1/4, R3 = 1/3, R4 = 1/2, R5 = 1, R6 = 1/4 E3 = 32V, E1 = 2V, E2 = 4V. http://dl.dropbox.com/u/9301772/Capture.PNG The Attempt at a Solution The schematic...
  44. L

    Diode paralell with a resistor problem.

    Today my teacher asked us a question Basically he said a match box was taped shut and a current was passed through the circuit a reading came up on the Ammeter, then the cell was switched around, and a current ran through the circuit but the Ammeter read a smaller reading than before. Why?
  45. teroenza

    Voltage drop across paralell resistor and capacitor

    Homework Statement Find the voltage drop across a resistor and capacitor in parallel. I am trying to understand how to deal with this using complex numbers. I may have a completely wrong notion of complex impedance. I thought I could treat the complex impedance like resistance, then take the...
  46. C

    How to Write Loop Equations for a Circuit with Multiple Resistors and Batteries

    Homework Statement I do not understand the solution provided for this problem. Consider the circuit with five resistors and two batteries (with no internal resistance) shown in the figure. (b) Solve for the current in the 4-Ω resistor. Homework Equations loop law junction law...
  47. P

    To double the power dissipated by a resistor you can

    Homework Statement 1) double the potential difference, ΔV 2) double the current, I 3) reduce the resistance, R, by 1/2 Homework Equations The Attempt at a Solution These problems are usually straightforward but I'm a little confused this time because I keep seeing all of the...
  48. S

    Resistor Voltage Drop Concept Question

    I'm currently studying electric circuits and can't find the answer to my question anywhere so far. I realize current is the flow of positive charge even though positive charges stay put in reality and that this is an old historic concept that is still around today because Benjamin Franklin...
  49. K

    How Do You Calculate Current in a 10 Ohm Resistor Using Kirchhoff's Loop Rule?

    Homework Statement Find the current in the 10.0 ohm resistor in the drawing (V1 = 24.0 V and R1 = 15.0 Ohm) Diagram: Homework Equations Kirchoffs loop ruleThe Attempt at a Solution well do i have to solve for both parts of the circuit if i just want to find the current at the 10.0 ohm...
  50. B

    Resistor network question Cant get it

    Homework Statement A network of 5 resistors is constructed to a 12.0V emf. the total current in the circuit is 12.0A. determine, draw and label the configuration for the network of resistors R1=1ohm, R2=1ohm, R3=1ohm, R4=1ohm, R5=4ohm Homework Equations The Attempt at a Solution...
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