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.

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

    Optimizing Power on a Resistor: Finding the Maximum Power

    Homework Statement Find the maximal power on resistor R. Homework Equations [/B] The Attempt at a Solution I used Thevenin theorem. I found that Z_t=5+j10 , and U_t= 10-j10. The maximum power happens in this case when $$R=|Z_t| = 5 \sqrt{5}$$ , and I get that P=6.18, while the answer is...
  2. C

    Average power on a resistor

    Homework Statement $$R=5 \Omega , C =50 \mu F, L=5 mH$$ are connected in series on voltage source $$u(t)=150 \sin (1000t)+100 \sin(2000t)$$. Find the average power on resistor R. Homework Equations [/B]$$ P=\frac{U^2}{R} $$, $$ U_{ef}= \sqrt{ \frac{1}{T} \int_{0}^{T} u^2(t) dt } $$The...
  3. U

    Plotting Bode of Resistor w/ DC Source: 20*log(0)

    I am ploting bode of resistor connected with DC source.So no freqvancy at all! The bode magnitude plot should be(or it should start from) 20*log(jw)=20*log(0) (jw=0 because we have dc source) what should be the value??for step of 5v... what should bode look like??
  4. A

    Find the resistance of a resistor using Ohm's Law?

    Hi, I have been at this problem for days and I can't seem to see what I am doing wrong. Here is the circuit layout along with my work As you can see I am running into problem getting values of current that do not add up equal to zero. My professor has never discussed how adding a wire like...
  5. kostoglotov

    Why isn't this largest voltage source given as negative?

    This isn't actually a homework problem, but it is an example in a my textbook that I have a question about... imgur link: http://i.imgur.com/2OglMH4.png Ok, I wanted to clarify some things. I understand that current flowing from a positive terminal to a negative terminal represents a...
  6. P

    Find emf and the inner resistor of the battery

    Homework Statement When the resistor is R1, in the circle there is the intensity I1 and when the resistor is R2, the intensity becomes I2.Find emf and the inner resistance.[/B] Homework Equations I=emf/R+r The Attempt at a Solution I1=efm/R1+r I2=efm/R2+r efm is equal I1*(R1+r)=I2(R2+r)...
  7. InsaneScientist

    Engineering Approach for solving voltage across a resistor in circuit?

    Homework Statement I must solve for the voltage across the resistor labelled R1 in the circuit above. The values given are the resistance of each resistor, the voltage of each voltage source and the current of the current source. Note: If referring to circuit loops consider them as being...
  8. A

    What is the solution to the 12 resistor cube problem using symmetry?

    Q. It is a classical problem in current electricity .The resistor cube consists of 12 resistors, each having a value r. What is the total resistance between the two diagonally opposite corners labeled A and H on the cube? Ans. The answer to this problem begins with that due to symmetry points E...
  9. xSpartanCx

    Faraday's law with loop of wire and resistor

    A coil 3.65 cm radius, containing 560 turns, is placed in a uniform magnetic field that varies with time according to B=( 1.20×10^−2 T/s)t+( 3.05×10^−5 T/s4)t^4. The coil is connected to a 600-Ω resistor, and its plane is perpendicular to the magnetic field. You can ignore the resistance of the...
  10. kostoglotov

    Power dissipated by resistor -- Right answer, but need insight

    imgur: http://i.imgur.com/9VILpYL.jpg Now, I can easily solve this by applying the formula P_R = \frac{(\Delta V_R)^2}{R} and get all the correct answers. However, the answers feel strange to me intuitively. In the formula above, lowering the resistance increases the power that is dissipated...
  11. J

    Power Dissipation in a Resistor: How Does Resistance Affect Energy Loss?

    Homework Statement Homework Equations P=V2/R P=I2R V=IR The Attempt at a Solution As the resistance of R increases, the potential difference across R increases, so the power dissipated in R increases too. But I can't seem to see how the power decreases afterwards. Is it because, as time passes...
  12. G

    Potential difference of each resistor

    Homework Statement What is the potential difference across each resistor? I know that I'll have to incorporate the V=iR equation but I don't know where to start though... My first attempt was with these: R1=4 R2=8 R3=5 R4=6 R5=3 24-I1R1-I1R2-I3R3+I4R4+I5R5=0 but this lead me nowhere so I...
  13. C

    Solving a Series Circuit with Unequal Resistor Powers

    Homework Statement Two resistors of equal rated voltages ##V_n##, and different rated powers ##P_{n1}= 50 W## and ##P_{n2}= 100 W## are connected in series on source of rated voltage. Find total power of a circuit. Homework Equations [/B]##P=\frac{U^2}{R} ##, ## R=R_1+R_2 ##The Attempt at a...
  14. M

    Finding current in a resistor circuit

    Homework Statement There are several parts, but the part I'm stuck on is: what happens if a jumper is placed from node A to node B? Calculate V_A and V_B, and magnitude and direction of the current through the jumper. The resistor values are R1=R2=2 kohms, R3=R4=1 kohm. Homework Equations...
  15. D

    Which resistor produces the most heat?

    Homework Statement Find the resistor that generates most heat. Homework Equations Principle of superposition. Voltage Div Current Div. Power = I^2R The Attempt at a Solution After aplying principle of super position and considering the voltage source in one scenario with current source open...
  16. M

    Inductor behavior connected directly to DC (no resistor)?

    If an ideal inductor is connected directly (no resistor present) to a DC voltage source, why does it behave like a short-circuit at time t=0? If voltage across an inductor is related to the change in current (i.e. di/dt), then shouldn't the voltage across the inductor be very large at time t=0...
  17. terryds

    What Is the Minimum Value of n for Resistors in Series and Parallel?

    Homework Statement The equivalent resistance of the series combination of two resistors is p.When they are joined in parallel, the equivalent resistance is q. If p = nq, find the minimum possible value of n. Homework Equations 1/Rparallel = 1/R1+1/R2+... Rseries = R1+R2+... The Attempt at a...
  18. hdp12

    KCL Nodal Analysis & Power to Resistor (Need help)

    Homework Statement Here is the homework problem I was given: The Attempt at a Solution Above is the work that I began, however, I have an overwhelming feeling that I am incorrect and also I don't know how to continue to the next part/parts. Would someone please help me? Thank you H
  19. S

    Why is the solution for the nonlinear resistor problem hard to understand?

    Homework Statement The problem and its solution are attached in the TheProblemAndSolution.jpeg file. Homework Equations V = RI G = 1/R The Attempt at a Solution I tried to understand what the solution said, but I'm still very lost. Here's what I'm stuck on.: When the solution says "Since...
  20. B

    Solve Resistor Problem: Imagine Voltage Source from a to b

    For this problem I am just wondering if it is proper to "imagine" there is a voltage source from a to b so that one may say the 5 ohm resistor right after a is in parallel with the 6 ohm resistor connecting the two wires. If not, how would I go about solving this? Thank you in advance.
  21. nothing909

    Finding voltage across a resistor in a circuit

    Find the voltage across the 4Ω resistor (resistor 3). This is all show in the pictures provided: I have started by reducing all the resistors into one resistor, but please take a look over my working and tell me if it's all correct. After reducing all the resistors into one, I used the...
  22. G

    Why resistor between +input and ground necessary in OP-AMP?

    Hello. Please see the attached image first. 1. The textbook seems say resistor to + input in this image is necessary to provide a return path to ground. I completely don't understand even what it mean. Could you help me to clarify this? 2. Instead of understanding directly what the book said...
  23. toforfiltum

    Mean power dissipated in resistor in ac circuit

    Homework Statement Homework EquationsThe Attempt at a Solution I am surprised that this question came up, I haven't learned ac circuits yet. I don't know how to solve this. I just added both values and current and divide it by two, which gives me 1.5A, since I thought it's the average but I'm...
  24. F

    What is the Net Resistance in this Complex Resistor Problem?

    Hey there! I'm having some real trouble deciphering this complex resistor problem. I have heard of the Kirchhoff voltage and current rules and do know how to use them to solve some problems but I'm not sure how to apply them in this context, or if they are even used to solve this. As seen the...
  25. toforfiltum

    Solving potentiometer problem with addition of resistor

    Homework Statement The emf of a battery A is balanced by a length of 75 cm on a potentiometer wire. The emf of a standard cell, 1.02V, is balanced by a length of 50 cm. What is the emf of A? Calculate the new balance length if A has an internal resistance of 2 Ω and a resistor of 8 Ω is joined...
  26. A

    BJT hybrid pi model,why "always" ro resistor is shown?

    In BJT hybrid pi small signal model, we have a resistor "ro" between Collector and Emitter. This resistor is to include the change in collector current when there is a small signal voltage change between collector and emitter. (due to early effect) I am finding that all BJT hybrid small...
  27. Salvador

    Where Can I Find a Thermo Resistor Safety Switch for My DIY Lamp?

    Good day , could someone please point me to a device that would have say two wire terminals and could interrupt the flow of current between them when a dangerous temperature is reached? the idea is simple , I built a lamp and I need some failsafe mechanism that would turn the lamp off when it...
  28. S

    Engineering Series/Parallel Resistor Circuits (Diagonal Resistor)

    Homework Statement http://i.gyazo.com/c6b73ca3a53b7d36bce59a0aa5009d27.png Homework Equations Kirchhoff's Current and Voltage Laws, Resistors in parallel and in Series. The Attempt at a Solution The main thing confusing me is the diagonal 6 Ohms, not too sure what it is parallel too and how...
  29. M

    Help with finding the right resistor

    so i need to reduce a dc 12v to dc 5v. do you know what type of resistor i should use? also could you please suggest an online calculator or an equation so that i can find the resistance i need in the future.
  30. S

    Figuring this circuit's amp before resistor one

    < Mentor Note -- thread moved to HH from the technical forums, so no HH Template is shown > https://drive.google.com/file/d/0B3gxtQyBRFkLQU9YdExMaTczTEk/view?usp=docslist_api Here is the copy of the circuit I am try to anaylze. I come up with three amps, but the answer book says .75 amps...
  31. R

    Circuit Questions -- Electrons flowing in wires and a resistor

    Homework Statement Homework EquationsThe Attempt at a Solution I have selected what I thought were the right choices in the original question. Resistors reduce current so electron flow should have been greater on the right. Also, the electrons flow opposite to current so potential is higher...
  32. Guidestone

    Strange questions about electrical circuits

    What's up people? I'm new in this wonderful forum. I have several questions about circuits, and they are not really common, I mean, I find them somehow complicated, but I would really come to enlightenment if you guys gave me some clues. 1.- So, let's suppose we got the simplest circuit, a...
  33. P

    Find power dissipated in circuit with a ground

    Homework Statement 1. Find the power dissipated by 12 ohm resistor 2. What is the potential at points a,b,c,d? Homework Equations P=I^2R I=V/R The Attempt at a Solution For a) 3v-IR-6v-IR=0 9v=I(18) I=0.5 P=0.5^2 * 12 = 3 watts But not sure if the ground changes anything b) unsure if ground...
  34. T

    Electrical circuit Source transformation Question

    I'm extreeeeamly rusty at basic circuit theory. I want to transform a sort of infinite arrangement of this circuit: The values themselves aren't important, just the representation of what's happening, all the verticle resistors are the same value as each other, and all the horizontal resistors...
  35. R

    AC Homework: 10 Ohms Resistor, 12 uF Capacitor, 28 mH Inductor

    Homework Statement A 10 ohms resistor, a 12 microFarad capacitor and a 28 mH inductor are connected in series with a 170 V generator. A.) At what frequency is the rms current maximum? B.) What is the maximum value of the rms current? Homework Equations A.) Fo = 1 / 2pi sqrtLC b.) Irms = Vrms...
  36. I

    How is a memristor different from a resistor

    I read that the memristor is described by the equation dφ=Mdq. If both sides are divided by dt, then dφ/dt=Mdq/dt. But dφ/dt=V and dq/dt=I. Then V=MI which is ohm's law. Isn't the constant M just the same as resistance?
  37. L

    Function of bias resistor in semiconductor detector

    Hi, I am working on CdZnTe detector. Can anyone please explain the function of bias resistor in radiation detector setup & how to select an appropriate bias resistor?
  38. MushroomLT

    Can a different Ohm rating resistor burn a pc motherboard?

    Hello, my motherboard recently has stopped working, so I returned it to warrany, they fixed it, but after a few months the board broke again, but unfortunatly the warranty has ran out, so I'm attempting to fix it myself in the freetime :D So I have found a resistor on the motherboard, that looks...
  39. kelvin490

    Charge accumulated at two ends of resistor/inductor?

    In a simple circuit are there any charges accumulated at two ends of resistor? There is an conservative and thus electrostatic electric field and potential difference across the resistor. It seems it is only possible if positive and negative charges are accumulated at two ends to provide the...
  40. CAH

    Power dissipated in variable resistor?

    See photo! Why does the power dissipated increase and then decrease (see graph)? Is it something to do with emf? Also can internal resistance change as the variable resistor increases/decreases or is it always constant? - this isn't one of the questions they ask I'm just wondering
  41. CAH

    Variable resistor and thermistors?

    If your doing an experiment to test how the temperature affects a thermistor (increase temp measure v and I...) why do you need a variable resistor in your circuit? Or if you don't NEED one what beneficial use may it pose anyway? Is it something to do with the current? Thanks
  42. 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...
  43. brainbaby

    Why is a 10k resistor needed in a Vbe temp compensated circuit?

    The following circuit is a Vbe temp compensated circuit Query : what exactly the use of the 10k resistor required to connect the bases of two transistors...we can also have a direct coupling to connect the bases of both transistors...what exactly the difference it could make by adding the...
  44. E

    Can You Solve This Infinite Grid of Resistors Problem?

    Could you solve this?
  45. A

    Temperature-Independent Resistor Combo

    Homework Statement For some applications, it is important that the value of a resistance not change with temperature. For example, suppose you made a resistor from a carbon resistor and a Nichrome wire-wound resistor connected together so the total resistance RT is the sum of their separate...
  46. AdityaDev

    Charging of resistor with resistance in parallel

    The cell can provide conatant emf ε and initial charge of capacitor is zero. Now current through resistor initially is zero and increases. But the potential difference across the capacitor is always a constant with magnitude ε. then ##\frac{q(t)}{C}=E## So ##q(t)=CE## which implies q is constant...
  47. J

    Finding Maximum Power Delivered to Resistor

    Homework Statement Part (a) has already been solved and determined to be 5kΩ, which has been confirmed by the answer key. The answer key also states that the maximum power able to be delivered to Ro is 957 µW, but doesn't give any workings or explanations on how to reach this answer...
  48. 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...
  49. B

    Average power dissipated in resistor

    Homework Statement Find the average power dissipated in the 30 Ω resistor in the circuit seen in the figure if ig=7cos20,000tA. Homework Equations KVL/KCL equations P=VI* (possibly) or I^2(R) The Attempt at a Solution I tried to do a mesh, but got I∆(60-j130) = 0, which isn't right . . . I'm...
  50. D

    Please help clarify use of resistor in this circuit

    Hello everyone. I'm trying to teach myself how electronics work and I've ran into some questions with this circuit. This is from Make:Electronics experiment 10. I understand R2 is resisting the flow to the gate so the transistor doesn't fry. I also understand R3 will restrict flow to the LED...
Back
Top