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. N

    FET common source analysis with source resistor

    Hi everyone, I have attached an image of fet amplifier in common source configuration. I want to have the ac analysis of this circuit. I am able to figure out the input impedance and the voltage gain. But I can't formulate for output impedance. According to me, while calculating output...
  2. L

    Cube of Resistor Problem - Nice one

    Homework Statement Asymmetrical Cube - Determine the equivalent resistance between points A and C’ of the circuit below. Homework Equations U = R.i The Attempt at a Solution This problem was my professor that created. I know how to solve it, but I would like to know if other...
  3. I

    Optimal Placement of a Resistor in a Circuit

    Am I correct in thinking that it would not matter if I place the 100ohm resistor after the 220nF capacitor (as shown in the picture), or before the capacitor?
  4. L

    Inverting OP AMP with 'hanging' resistor in feedback network

    Homework Statement Find Vo/Vin.I understand perfectly how to do this question. It simply involves an application of ohm's law to find i1, then KVL around the first loop. KCL at the top, and KVL around the second loop. Then to solve simultaneously. My issue however Is why the mechanics of...
  5. R

    Is resistor a conductor or an insulator?

    Is resistor a conductor or an insulator?
  6. T

    Square loop, find the charge in the resistor

    Homework Statement A square loop of wire is made up of 50 turns of wire, 45 cm on each side. The loop is immersed in a 1.4T magnetic field perpendicular to the plane of the loop. The loop of wire has little resistance but it is connected to two resistors in parallel as shown. (a) When the loop...
  7. P

    Discharging capacitor without resistor

    Hi all, So I created this account specifically to get some clarification on capacitors. I've been reading alot, but can't seem to find any info on whether a resistor is essential in series to discharge a capacitor. Think of the simplest circuit possible that switches between a battery to...
  8. O

    Equivalent Resistor Calculation for Series and Parallel Circuits

    Homework Statement Calculate equivalent resistor The Attempt at a Solution Req=(10 series 5)//(10)//(3)//(2)//(9 series 40) series 8//(4) I am not sure in the bolded text, is 9Ω connected serially with 40Ω.
  9. B

    Temperature difference in a resistor

    Hey, I'm an absolute newbie and have just this one question: When I installed LED map lights, they would flicker unless the door was open. After someone advised me that I should solder resistors (which I did) the problem was fixed, BUT: I would like to know what is the difference in temp as I...
  10. Femme_physics

    Engineering Transfer function of a circuit with a resistor, capacitor, and coil

    Homework Statement Find the transfer function, Vout(s)/Vin(s) The (s) signifies the laplace plane Homework Equations The Attempt at a Solution I'm keenly aware there is an error here (at least from comparing with the answer sheet). Can you tell me where I went wrong?
  11. B

    How Does a Resistor Affect Voltage Drop in a Circuit?

    I'm curious the amount the voltage would drop across a resisitor. If you know the power going into the resistor and the maximum voltage allowed is say, 50V. How would that resistor effect the voltage? I understand the voltage would decrease, and when substituting and solving equations the new...
  12. C

    Given impedance, find voltage drop across resistor

    Homework Statement Determine the voltage V0 in the following network if the impedance Z contains: a. a 0.5 mH inductor b.a 10 μF inductor Homework Equations Voltage division for 2 series resistors: (v in)(resistor/total series resistance) ZL = ωLj Zc = -1j/ωC Z = ZL + ZC + R Zmagnitude =...
  13. K

    What is the current flowing in resistor BC in a complex circuit?

    Homework Statement AB, BC and CD are three resistors connected together at B and C. AB = 12 ohms, BC = 7 ohms, CD = 6 ohms. A battery of emf 48V and internal resistance 0.5 ohms has it positive pole connected to B and its negative connected to D. A battery of emf 74V and internal resistance 1...
  14. P

    Electric circuit problem, finding current through a resistor

    1. The diagram attached shows part of an electric circuit. What is the current through resistor R1? To summarize: I=6.0 A R1 = 11.0 Ω R2 = 33.0 Ω R3 = 67.0 Ω R2 and R3 are in parallel, and R1 and R2 and 3 are in parallel. I know we aren't supposed to attach pictures of questions...
  15. P

    Potential drop when current flows through a resistor

    What is the reason for the potential drop when current flows through a resistor? Is it due to conversion of potential energy of the electrons into thermal energy while flowing through the resistor?
  16. L

    Finding the current and the voltage across each resistor

    Homework Statement Find the current and the voltage across each resistor. volts is 24v R1=270 ohms R2=330 ohms R2=1.2k ohms R4=1.2k ohms Homework Equations The Attempt at a Solution This is not a homework its more like a study guide. He gave us the answer for just the...
  17. J

    Resistor and power output varying with a distance x

    Homework Statement Figure 29 shows a battery connected across a uniform resistor R0. A sliding contact can move across the resistor from x=0 at the left to x=10 cm at the right. Find an expression for the power dissipated in the resistor R as a function of x. Plot the function for ℰ=50 V...
  18. C

    Find current through inductor that parallels a resistor

    Homework Statement The switch in the circuit has been closed for a long time before it is opened at t = 0. Find: a. IL(t) for t > 0 b. i0(t) for t > 0 c. V0(t) for t > 0 Homework Equations equivalent resistance, equivalent current, equivalent voltage voltage...
  19. J

    How Do I Determine Equivalent Resistors in a Circuit?

    Homework Statement Hey, I've always had problems with circuits and finding out equivalent resistors, and identifyuing which are in parallel, and which are not Homework Equations I need help with the circuit attached. Can someone clear this problem with circuits once and for all. PS: I...
  20. P

    Finding delay angle ,Vrms, Irms using AC voltage/ load resistor

    Homework Statement From the average power consumed by the lamp in a light dimmer circuit connected to 240V AC main, What is the expression for RMS voltage, calculate the range of values of the delay angle α,(i)RMS voltage (ii)RMS current in the lamp, (iii) the average power if its nominal...
  21. Z

    Tricky circuit with variable resistor

    Homework Statement An electric circuit comprises two series resistors A and B, the first of which has a given resistance R_A and the second variable resistance R_B, over which a constant DC voltage U is added. How shall the resistance R_B be selected so that the power P developed in resistor B...
  22. O

    Explanation on Shunt resistor from meter

    I know meter shunts are used to direct most of the current away from the meter coil but my question is if you direct most of current away from the coil, how is the meter measuring the current flow accurately. Im kinda slow in the head so no complex fried banana explanation. tnx
  23. K

    Engineering Voltage response of a resistor in an AC circuit

    Homework Statement For the circuit below, assume the source phase angle is 0° Write the differential equation which would allow you to find the voltage response across resistor R2. Using the General Solution for the solution of such a differential equation write the complete...
  24. J

    Resistor in a Circuit with varying resistance.

    Homework Statement In the circuit of Fig. 23, ℰ, R1, and R2 have constant values but R can be varied. Find an expression for R that results in the maximum heating in that resistor. Homework Equations V=IR resistors in parallel add up in inverse, resistors in series add up directly...
  25. B

    Analog multiplexer - resistor at input

    Hello PF! I've been quite busy on my faculty, doing my academic final work. Anyway I need somebodies expertise which involves analog multiplexers. I am using MPC506 Datasheet http://www.ti.com/lit/gpn/mpc506 I tested it and gives nice result at 5 MHz sine wave, which is more than good for...
  26. J

    What is the voltage across the resistor?

    Homework Statement The amplitude of the voltage across an entire series circuit is 17 V. The inductor alone has an amplitude of 30 V and across the capacitor it is 22 V. To the nearest tenth, what is the voltage across the resistor? Homework Equations The Attempt at a Solution...
  27. ch3cooh

    Is a resistor a dependent source?

    Is a resistor a voltage-controlled current source? WHY? I think it is but I don't know whether I'm correct.
  28. D

    Find the current flowing through resistor

    Homework Statement The power supply in the circuit shown has V(t) = (120V)cos(ωt), where ω = 310 rad/s. Determine the current flowing through the resistor at time t = 9.7 s, given R = 600 Ω, C = 18 mF, and I(0) = 0 A. As a reminder, Kirkhoff’s voltage law for this circuit (Eq. 8-1.3 in the...
  29. M

    Help drawing equivalent resistor diagrams.

    Homework Statement I really just need help understanding how to re-draw a resistor diagram after calculating an equivalent resistor. Now in the picture given in the attachment, you can see that R1 and R6 are in series with each other when I compute their equivalent resistor(R1+R6), on what...
  30. S

    Engineering Find power of resistor and source in AC circuit

    Homework Statement If an average power of 500W is dissipated in the 20Ω resistor, find Vrms, I S RMS, the power factor seen by the source, and the magnitude of VS (Based on circuit in attached diagram) Homework Equations Pave= Irms*Vrms*pf*\frac{1}{2} Imaginary number referred to as...
  31. F

    Determining current through a resistor

    Homework Statement A pot containing 15 kg of water at 30 C is heated until all the water is at 90 C, by placing a resistor (having resistance R=930Ω) in the water and running a current through it. What current must be placed through the resistor if the 15 kg of water is raised from 30 C to...
  32. L

    What Is a Crosspoint Switch in Electronics?

    Does a criss-cross resistor network exist? I need something (preferably passive), that comes in both criss cross and straight paths. Maybe a switching array of some sort? I am looking for something that connects- A-->A B-->B C-->C D-->D and A-->D B-->C C-->B D-->A It can be...
  33. N

    Help with Simple Resistor problem from physics resistor chapter

    Homework Statement http://imageshack.us/a/img69/3384/rseistors.jpg Homework Equations Resistors in series and parallel formulas. The attempt at a solution Very confused with part (b)! So in the first square or w/e you call it (left side), R1 in series with R1 so that's...
  34. M

    How to achieve a zero resistance on a force sensitive resistor?

    Hi all, I've a square force sensitive resistor with a resistance larger than 1MΩ when no pressure is applied. When I apply pressure with my hand, the resistance drops to about 480kΩ I'd like to know if there is a way to make the resistance drop to almost 0Ω when any pressure is applied and...
  35. E

    Is My Pull Up Resistor Calculation Correct?

    http://i.imgur.com/TbYIHnb.png?1 So, if I have a pull up and apply a current source. How would I need to read/calculate resistance? V=IR I = 5V/8k = .0006A would result in a voltage drop of close to 5V Using a current source/Voltage reader I supply .0006A which should equate to ~5V...
  36. B

    Electric Potential Drop Across A Resistor

    Hello, As a charge traverses through a resistive circuit element it will have a certain amount of potential energy before entering the circuit element; and as it passes through, it's potential energy will decrease (due to it converting to kinetic energy, and collisions)--this I iunderstand...
  37. JJBladester

    Single battery & Single resistor: Series or parallel?

    Homework Statement Can a circuit be both series and parallel? Not series-parallel, but series *and* parallel? Let's say you have a battery with its positive terminal connected to a resistor and its negative terminal connected to the other end of the resistor. Due to conservation of...
  38. C

    Calculating Resistance for Cylindrical Shell Resistor

    Homework Statement A copper resistor has the shape of a cylindrical shell. What is the resistance of this resistor if its length is 1m, its inner radius is 0.1cm, and its outer radius is 0.2 cm? What is the radius of a solid wire of circular cross section with the same length and the same...
  39. K

    Photodiode in parallel with resistor and capacitor

    hello , I am trying to detect a laser pulse with a photodiode , having a power of 100w max of the laser beam with pulse wave of 1microsecond . when i see the output in ocilloscope the wave do not have 1 microsencond this is without any resistor or capacitor. so my question is that what...
  40. M

    Is My Redrawn Resistor Circuit Correct?

    Hello, I am a new member, just signed up, I have browsed the forums for a bit and have always found some great info here...Today I have a question that I worked through, but really wanted a confirmation that I am on the correct path. I attached a redrawing of a resistor circuit, if it is not...
  41. W

    Find the current in each resistor.

    So I believe I have labeled all my junctions correctly, I did not label one right before the 3rd resistor because I know current won't flow into the positive terminal going from i1. I believe I need another equation fro the junction rule but I don't know if I should use b or e and what should I...
  42. C

    Capacititive Circuit - discharging through lamp and resistor

    Homework Statement The power supply for a large flash lamp is shown below where a 500 V DC power supply changes up at 10 μF capacitor that then discharged through the flash lamp. Such a system is potenitally lethal, so to reduce risk a bleed resistor Rb is connect across the capacitor to...
  43. V

    Current of electricity- power of a resistor in parallel

    I got the answer by comparing I2R of the circuit with resistor R but why do i have to use R/2 for power of resistor R?( P= (0.5I)^2 (R/2)) I know its parallel to Resistor Q but i want to find the power of that component so shouldn't it be P= (0.5I)^2 (R) instead?
  44. G

    Engineering Electrical Circuit Question - Maximum Power Dispated in Resistor

    Homework Statement http://img855.imageshack.us/img855/6951/captureaww.png Homework Equations The Attempt at a Solution Is one allowed to find R_{Th} by simply short circuiting all voltage source and opening all current sources and finding the equivalent resistance while keeping...
  45. J

    Find the current through the 100 Ohm resistor:

    Homework Statement Find the current through the 100 Ohm resistor: http://imgur.com/sohdpyE The Attempt at a Solution So I was able to simplify the 100 and 500 resistors, as well as the 20, 20 and 10 series resistors, but I can't seem to discern at all whether any of the remaining ones...
  46. N

    Engineering Help with this confusing circuit test tmrw Find i across resistor.

    Help with this confusing circuit! test tmrw! Find i across resistor. http://imageshack.us/photo/my-images/202/circuitu.jpg/ my teacher lectures to fast and i don't understand the notes i put down. can someone explain this one to me please??
  47. S

    How can I Find all V in Resistor, and all Currenst flowing?

    https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-ash4/315877_586838821344606_1596614123_n.jpg Homework Statement R1=10ohms R2=10OHMS R3=15OHMS V1=10V V2=15V Homework Equations Using Ohms law or Kirchoffs Law The Attempt at a Solution
  48. O

    Is a Resistor a Capacitor in a Simple Circuit with a DC Current?

    Suppose a resistor is connected on both sides to a copper wire, in a simple circuit with a battery. Resistor and wires are cylinders of equal diameter. A DC current is flowing through the resistor and the wires. The current is axial everywhere, and the electric field is also axial. The strength...
  49. G

    Engineering Max Voltage Across Capacitor & Resistor in a Circuit

    Homework Statement For the circuit in the picture below, with V_{c}(t=0) = 0 and a voltage source with period T described by V_s(t) = \sum_{-\infty}^\infty (-1)^{n}g(t-nT) where g(t) = 7[u(t)-u(t-T)]\quad [Volt] and u(t) is a step function described by u(t) = \begin{cases} 1 &...
  50. P

    Color band colors for 1kΩ resistor

    Homework Statement What are the color band colors and associated band values for a 1kΩ resistor The Attempt at a Solution resistor color codes are read like so: ab*10^c±tol 1kΩ=10*10^2 a=1, b=0, 10=c Now I get confused. What should the tol be?
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