Resistors Definition and 603 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. R

    Resistors in a circuit/ Calculate total resistance

    I'm having problem trying to calculate total resistance in resistor arrangement like this one: http://o3xn.files.wordpress.com/2012/04/different.png Before I go into any more detail with the original problem, I just want to say that whenever I get this "closed" type of circuits, I like...
  2. Femme_physics

    Can I convert a potentiometer to 2 resistors?

    http://img855.imageshack.us/img855/8894/figgg.jpg Is that how it works basically?
  3. O

    LR Circuit with resistors in parallel

    Homework Statement Homework Equations V = IR I = V/R (1 - e^(-t / τ)) τ = L / R The Attempt at a Solution I'm so thrown off by these two problems. Every example I have done has nothing in parallel and it is simple, but my homework question involves having to do a...
  4. E

    Are Resistors in Parallel if Another Resistor is Between Them?

    For the circuit shown, is the 3 ohm resistor in parallel with the 5 ohm resistor if the 1 ohm resistor is "in the way?"
  5. J

    Determining resistors in AC/DC circuit

    I have trouble with determining the type of resistor used in the following problem. A type of black box is connected to an AC/DC circuit. The values of U and I are given in the DC circuit, the value of R is not. The values of U and R are given in the AC circuit, the value of I is not. In...
  6. N

    Calculating Potential Difference in a Capacitor with Resistors Circuit

    Homework Statement In the following circuit, the ideal battery has an electromotro force of 12V, the resistances R1=4 ohms and R2 = 6 ohms. The capacito of 6x10^-6 F can be found discharged initially. The switch closes at t=0. Calculate the potential difference in the capacitor when t=2\tau...
  7. QuarkCharmer

    What is the Resistance R for 295 Watts Dissipation in a Network of Resistors?

    Homework Statement Find the resistance of R, such that the network dissipates 295 Watts. Homework Equations \frac{1}{R_{eqp}} = \Sigma \frac{1}{R_{i}} R_{eqs} = \Sigma R_{i} P = \frac{V^{2}}{R} = VI = I^{2}R The Attempt at a Solution What I did was first find the equivalent resistance of...
  8. M

    Are the 3 Resistors in Parallel? Check Here!

    Are the three resistors that I circled in the paint doc in parallel??
  9. C

    Resistors connected in parallel and series

    Homework Statement Find the equivalent resistance between the points A and B of the network shown in figure ( file has been attached ) Homework Equations Req( series) = R1+ R2 + R3 .. + Rn 1/Req ( parallel) = 1/R1 + 1/R2 + 1/R3 .. + 1/Rn The Attempt at a Solution We have to find...
  10. S

    Energy dissipated over time by resistors

    Homework Statement In the figure below, R1 = 9.00 , R2 = 23.0 and the ideal battery has an emf = 12.0 V. (a) 0.24 A (b) How much energy is dissipated by all four resistors in 1.00 min? The Attempt at a Solution Not sure where I went wrong. P = inet2Rnet P = i12R2 +...
  11. J

    Unlimited resistors to build a 5 watt circuit with resistance of 10 ohms.

    Okay well my issue is from a basic problem. The problem is you are given an unlimited number of 10 Ohm resistors. They can only handle 1 watt of dissipation and you need to create a circuit that has a total resistance of 10 Ohms, and has a power dissipation of 5 Watts. They are actually looking...
  12. A

    3 batteries, 5 resistors using KCL & KVL

    Homework Statement 1. Using Kirchhoff’s Laws, find all the currents flowing in the circuit. 2. Hence, determine the voltage across each resistor and show that all loops comply with KVL Homework Equations KVL and KCL The Attempt at a Solution Please see the pictures...
  13. S

    Resistors: Series/Parallel Current/Voltage Rules

    resistors in series share the same current, and resistors in parallel share same voltage is this always true? or exist some exceptions? thanks
  14. S

    Circuit With Three Batteries Two Resistors

    In the above circuit: V1 = 12.00 V V2 = 6.00 V V3 = 3.00 V R1 = 220.0 R3 = 270.0 Because of the direction of the batteries, a student looking at the above circuit makes this guess for the direction of current across resistors R1 and R3. Is the student...
  15. S

    Resistors that doesn't affect the others

    hello! we got this experiment, R1= 46.8 R2= 46.8 R3= 148.9 R4= 147.7 R5= 217 RT= 71.1 as we can see, r1 and r2 are in series, while r3 and r4 are in series also and they are parallel to each other while r5 is on the middle, we got the RT by solving for r1,r2,r3 and r4. and here's...
  16. E

    Nodal analysis with parallel resistors

    I'm trying to determine v,oc using nodal analysis. I have labeled the two node voltages at the top v,1 and v,2. When doing the KCL equation for node voltage 2, I run into the 1.1 kohm and 2.3 kohm parallel combination. Is it valid if I just combine these parallel resistors into one resistor?
  17. J

    Theories on Series and Parallel Resistors

    Homework Statement 1. When three different resistors are connected in parallel to a battery whose voltage output is V as in figure 2 in the lab manual: (Choose all relevant answers below) 2. When three different resistors are connected in series with a battery whose voltage output is V...
  18. C

    Circuit help? with two batteries and resistors

    Homework Statement If R3 = 14Ω: a. What is the current out of the 24 V battery? b. What is the voltage drop across the R3 resistor? c. What is the power dissipated by the 12 Ω resistor? Homework Equations I=V/R V=V(R3/Rtotal) P=I2R The Attempt at a Solution Answers...
  19. C

    Series and parallel circuit with multiple resistors?

    Series and parallel circuit with multiple resistors?? Homework Statement If R1 = 27Ω and R2 = 7Ω : a. What is the equivalent resistance of the circuit? b. What is the current from the battery? c. What is the voltage drop across the R1 resistor? Homework Equations I=V/R ΔV=-IR...
  20. C

    How Much Power Is Dissipated in Each Resistor in a Multiloop Circuit?

    Homework Statement Three resistors, R1 = 32 Ω, R2 = 45 Ω, and R3 = 60 Ω, are connected in a multiloop circuit, as shown in the figure. Determine the amount of power dissipated in the three resistors. Homework Equations loop law junction law The Attempt at a Solution (1) i1 +i2...
  21. T

    Engineering Inductors v/s resistors in AC circuit.

    "why are inductors preferred over resistors in reducing current in an AC circuit?" The quoted question from a recent exam has caused a little dilemma regarding it's interpretation and answer. 1) what does 'reduce' refer to? 2) inductors are preferred as the impedence is dependent on the...
  22. K

    Circuit with 2 Batteries and 6 Resistors

    Homework Statement A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18 V and V2 = 12 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 56 Ω, R2 = R6 = 157 Ω R3 = 118 Ω, and R4 = 97 Ω. The...
  23. R

    Resistors in Series, in Parallel

    Homework Statement See the attached image. Homework Equations V=IR, Kirchoff's Law The Attempt at a Solution The voltage drop across resistors in parallel are equivalent due to Kirchoffs law (at least I think so?), so V=R(eq,top)I(top)=R(eq,bottom)I(bottom)-->...
  24. K

    Circuit 1 with Resistors and Battery

    Homework Statement A circuit is constructed with five resistors and a battery as shown. The battery voltage is V = 12 V. The values for the resistors are: R1 = 75 Ω, R2 = 127 Ω, R3 = 129 Ω, and R4 = 130 Ω. The value for RX is unknown, but it is known that I4, the current that flows through...
  25. H

    Circuit with Resistors and a Battery

    Homework Statement A circuit is constructed with five resistors and a battery as shown. The battery voltage is V = 12 V. The values for the resistors are: R1 = 54 Ω, R2 = 142 Ω, R3 = 148 Ω, and R4 = 109 Ω. The value for RX is unknown, but it is known that I4, the current that flows through...
  26. P

    Calculating Voltage Across a Capacitor in a RC Circuit with Two Resistors

    Homework Statement Given a circuit with two resistors, R and r, and a capacitor of C, and EMF of V0 as shown in the diagram, find the voltage across the capacitor during charging. Prove that this voltage, V is given by V = V0 (r/(R+r)) (1-e-((R+r)t)/(RrC)) Homework Equations N.A...
  27. R

    Homework Question on resistors in series, in parallel

    Homework Statement See attached image. Homework Equations V=IR, Kirchoff's Law The Attempt at a Solution I thought that since the resistors are in parallel, the voltage drop across each one would be equivalent, so V=I1(14)=I2(38)=I3(7)=I4(Rx). From here I became stuck. Please help!
  28. 4

    Question about resistors in Parallel

    Homework Statement I need to devise an experiment to show that the total resistance decreases as additional resistors are added to a parallel circuit of resistors. All resistances of the resistors are the same. Homework Equations R(Total)=1/R(1)+1/R(2)+...+1/R(n) The Attempt at a...
  29. C

    Number of Resistors needed for a maximum power

    Homework Statement How many resistors, R = 70 ohms can be connected in a series circuit when the maximum power loss of the circuit is 1800W. and the voltages supply is 127V Homework Equations Number of resistors! The Attempt at a Solution P = V2 / x*R x*7=1272/1800 x=1.28 so...
  30. B

    Engineering Multiple Resistors and Short Circuit

    Homework Statement This is more of a concept question rather than a HW problem, but I have two Circuits shown in the image attached. I am not really understanding how a short would affect resistance in these cases. 2. The attempt at a solution For figure 1 I am considering one of two...
  31. L

    Equivalent resistors in resistor networks

    Homework Statement http://i134.photobucket.com/albums/q100/megajette2/Resistornetwork.png Homework Equations parallel resistors share the same nodes or terminals and simplify to (a*b)/(a+b). in series resistors values are added. The Attempt at a Solution...
  32. C

    How to Calculate Power Dissipation in Resistors?

    Calculate the power dissipated in R1, R2 and R [/b] Previously i worked out the Current I1, I2 and I3 so i planned to use this to calculate the power dissipated; For current i got; I1= 0.8409 A I2= -0.4545 A I3= 0.39 A I used I^2/R to get the following answers R1 =...
  33. S

    Finding h parameters when capacitors and inductors involved with resistors

    Homework Statement Find the h parameters of the following systems:- ---L---------C-- : : R : : ---------------- L= j5 ohm C=-j5 ohm R=1 ohm Homework Equations The above questions has to be solved manually as well as simulated...
  34. Z

    Pull Up Resistor Basics - Value & Function

    hi there i have been reading up on the function of pull up resistors from the text:http://ti.tuwien.ac.at/ecs/teaching/courses/mclu/theory-material/Microcontroller.pdf and on page 37 it talks about it. in their example of the pull up resistor with the switch. i was wondering if they circuit...
  35. Z

    Resistors, parallel line notation?

    I was looking at an answer regarding resistors, and saw the notation; R = R1 + R// where 1/R// = 1/R2 + 1/R3 I was wondering what the two parallel lines after the R indicate? Thanks.
  36. F

    Varying Resistors in Bridge Circuits?

    What happens to the system response if all four resistors are equal. One of the resistors is an RTD.
  37. P

    Equivalent resistance of a cube of resistors

    Homework Statement Twelve resistors, each one with a resistance of R ohms, form a cube (see attached figure). Find R17, the equivalent resistance of a diagonal of the cube. (The first attached picture was scanned from the book "Physics" by Halliday, Resnick and Krane, 4th edition.)...
  38. L

    Voltage across resistors - Series & Parallel

    Hey, I have a circuit which you can see in the images attached. I had 3 questions and I *THINK* I've answered one of them. But I can't seem to get to the next part. Here's the questions below Questions: a) The total Resistance (Rt) of the circuit. b) The voltage across each resistor, V1, V2...
  39. P

    Conceptual question on electron flow between two types of resistors

    Hey, I have a question on resistivity. When I first studied circuits as an undergrad, I just accepted the principle of voltage division and related things they taught us. I now major in condensed matter physics and now having seen the formalism for conductivity in the Drude model and the...
  40. G

    Maximum Power transfer theorem ( Power dissipation in resistors in circuits)

    the equation P = (E2R) / [(R-r)2 + 4Rr] We say that when R=r , P = E2/4R which is said to be maximum.. But if I say R→∞ , then r→0 and then P = E2/R which is greater.. So, shouldn't power be maximum for max R ?
  41. S

    Why do birds on power lines not act as resistors?

    Imagine a circuit with a cell and no resistors. If I connected a resistor to two points in the circuit, would a current flow through it? Does a bird on a power line act like this? Why does it not get electrocuted? Sorry if this is a stupid question - I'm terrible with electronics! :blushing:
  42. hxtasy

    Use resistors to simulate heat from microprocessor?

    Hello, I am playing with fan placement on a computer i am building and i am currently calculating (with solid works flow simulation) how the fans will cool the processor heat sink. I'm not really a theory type of guy, i like to test real world. Basically what i want to do is simulate the...
  43. V

    Engineering Infinite Ladder Circuit (Not with Resistors)

    Homework Statement Homework Equations Capacitive Reactance Xc = 1/ωC ; Inductive Reactance XL = ωL ; Some Phasor Algebra etc., The Attempt at a Solution Well, Basically like we solve the circuit for resistances with DC Supply, I tried to assume the total impedance of the Circuit as...
  44. S

    RL circuit with three resistors

    Homework Statement http://i.imgur.com/22jq3.png Three identical resistors are connected to a battery, an inductor, and a switch as shown in the figure. (The values of all circuit elements are given below the figure.) The switch has been open for a very long time, and then it is closed...
  45. S

    Final current through resistors

    Homework Statement The diagram below depicts an RC-circuit where C = 3.45 F, = 29.0 , = 28.0 , and = 3.00 Volts What is the current through immediately after the switch S is closed? 1.03×10-1 A What is the current through immediately after the switch S is closed? 1.07×10-1 A What...
  46. L

    General Formula Resistors Polyhedron

    Hello all, Does anyone know of any general formula for the equivalent resistance between two opposite points of a regular polyhedron (cube, dodecahedron ..) with all the resistors equal to R?
  47. T

    Voltage across resistors in series and parallel

    So I must be missing some crucial knowledge in my knowledge of electrostatics because I simply don't understand how this works. I'm given a circuit like this: [PLAIN]http://img3.imageshack.us/img3/8730/circuiti.png and I find out the voltage across bulb B is the same as that across the 10...
  48. D

    Can capacitors be viewed as non-ohmic resistors?

    Looking at the units involved with the Ohm's equation and the capacitance equation I found this much: V=iR C=q/V So... C=q/(iR) and i=q/t so... C=t/R and R/t=1/C Basic stuff. So capacitance is proportional to the inverse of the resistance. This would help explain why resistors...
  49. A

    How to Build a DC-AC Converter Without Inductors?

    How to build a DC-->AC converter using resistors capacitors and diodes (no inductors) I have been trying to learn electronics (I am familiar with the principles, just have no experience designing complex circuits to fulfill purposes), so I went to RadioShack, got myself: breadboard assorted...
  50. H

    Current after passing all resistors

    Homework Statement Find the current at point I: [PLAIN]http://img690.imageshack.us/img690/8508/circuit.png Homework Equations V=IR The Attempt at a Solution It seems there should be no current at point I, since there is no voltage. The total resistance in the circuit is 77...
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