What is Equivalent resistance: Definition and 209 Discussions

Practical capacitors and inductors as used in electric circuits are not ideal components with only capacitance or inductance. However, they can be treated, to a very good degree of approximation, as being ideal capacitors and inductors in series with a resistance; this resistance is defined as the equivalent series resistance (ESR). If not otherwise specified, the ESR is always an AC resistance, which means it is measured at specified frequencies, 100 kHz for switched-mode power supply components, 120 Hz for linear power-supply components, and at its self-resonant frequency for general-application components. Additionally, audio components may report a "Q factor", incorporating ESR among other things, at 1000 Hz.

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  1. A

    What is total equivalent resistance and power dissipated?

    Another one.. I'm sorry but I will likely spend tomorrow and today here with you guys asking for help and mooching solutions. Same deal, badly explained unit. We spent 15 minutes on this. Attached questions as jpg... Homework Statement How do I find total equivalent resistance? What does...
  2. C

    Two simple questions about equivalent resistance and kirchoff laws

    two simple questions about equivalent resistance and kirchhoff laws! pleaseeeee! :D EQUIVALENT RESISTANCE: Hi everybody . greetings from Peru.I know it's a dumb question but help please .please read below Homework Statement For the network shown in the figure, show that the resistance Rab =...
  3. R

    Determining the equivalent resistance of an irreducible network of resistors

    Homework Statement Alright so I am having trouble finding the equivalent resistance of something like this Without "hooking it up" to a current source and solving a large system of equations to find the voltage drop across the network and therefore the resistance. Is there a faster...
  4. L

    Resistance: find the equivalent resistance.

    Homework Statement Homework Equations Resistors in series (in a straight line) add. Like R + R = 2R. And if in parallel, they inversely add. 1/R_total = 1/R1 + 1/R2 So, I have no idea how to "simplify" this. Basically trying to find the total resistance. Thanks.
  5. R

    What are the equations for calculating equivalent resistance in a circuit?

    Homework Statement A circuit extends forever to the right, and all the resistors have the same value ##R##. Calculate the equivalent resistance measured across the two terminals at left. Homework Equations The series and parallel equivalent resistance equation. The Attempt at a...
  6. Q

    Engineering Simple circuit, find equivalent resistance seen by the source

    Homework Statement For the circuit shown in Figure, find the equivalent resistance seen by the source. How much power is delivered by the source? http://sphotos-b.xx.fbcdn.net/hphotos-snc7/304377_496325960386924_988412599_n.jpg Homework Equations Req = R1R2 / R1+ R2 P = V^2 / R Thanks you...
  7. Q

    Basic equivalent resistance problem

    Homework Statement Find Rab https://sphotos-a.xx.fbcdn.net/hphotos-ash4/199915_496321627054024_1130826860_n.jpg Homework Equations Req = R1R2 / R1+ R2 The Attempt at a Solution bottom 2Ω resistors in series ---> Req1 = 4Ω top right 12 and 4 Ω in parallel ---> Req2 = 3Ω this...
  8. L

    Finding the equivalent resistance of this circuit.

    Homework Statement I got this on a quiz today - Find the equivalent resistance between E and F. Now, the problem with this question is that I get TWO different answers when I trace from: 1. e to f 2. f to e I know one of them is definitely wrong (or maybe both are?), but I don't...
  9. O

    Equivalent Resistance/ resistors in series and parallel

    Homework Statement Find R_AB in the network. Look at attached file "Problem"Homework Equations R_S= R1+R2+R3+...Rn (for series resistors) 1/RP= 1/R1 + 1/R2 + 1/R3 + 1/Rn... (for parallel resistors) V=IR (ohm's law)The Attempt at a Solution Look at attached file "Problem Attempt" I know I'm...
  10. B

    Circuit Simplification (Equivalent Resistance)

    Homework Statement Determine the equivalent resistance of this circuit. http://img444.imageshack.us/img444/5137/19910965.png The Attempt at a Solution So I realize that both of the 6 ohm resistors on each side are in series with each other. However, I am stuck after that part since I do...
  11. S

    Equivalent Resistance: Simplifying Circuits with Symmetry

    how can i solve the equivalent resistance? I assume R = 2 and I = 3, I know I in node A will be divided. It's just that I don't know what direction I will go to solve for Voltage so I can solve the equivalent resistance. Is Req = 4/3 Ω ? on[/b]
  12. S

    Find the equivalent resistance of a circuit below

    Find the equivalent resistance of the circuit shown below. Each of the six resistors has a resistance of 12 ohm. I just want to make sure I calculated everything right. I don't have the solution available. Labelling the resistors from my left to the right: R1, R2, R3, R4, R5(bottom), R6...
  13. Saitama

    What is the equivalent resistance of this circuit?

    Homework Statement http://i50.tinypic.com/w0ggl.png Homework Equations The Attempt at a Solution I am stuck at part (a) (i haven't yet tried the part (b)). I really have no clue on how should i go on finding the equivalent resistance, i don't see a way to reduce it to simpler...
  14. S

    Find the equivalent resistance seen by the source

    Homework Statement Find: a) the equivalent resistor seen by the source; b) value of i0; c) value of v; d) value of v0. http://img823.imageshack.us/img823/4406/dasso.jpg Homework Equations Kirchoff's laws and Ohm's laws The Attempt at a Solution To solve b,c,d I need...
  15. S

    Multiloop circuit: find equivalent resistance

    Homework Statement Find equivalent resistance in this circuit. (picture is in the attached files section)Homework Equations Series: Req=R1+ R2. . . Parallel: 1/Req = 1/R1 + 1/R2 . . . The Attempt at a Solution It seems to me that the 2nd 2ohm resistor (the one that's pointed vertically) has 2...
  16. N

    Estimated equivalent resistance

    "Estimated" equivalent resistance Homework Statement Suppose I have a circuit like the one below, how will you "estimated" the equivalent resistance without using calculation? I know how to calculate equivalent resistance by using Formula: R1 * R2 / (R1+R2) . But can anyone use their logic...
  17. F

    A problem with equivalent resistance

    Homework Statement Find the equivalent rezistance in the following (see the attachament) if the rezistance for all the resistor are R ? what is the resistance from AB, AC, AD?
  18. S

    Why Does I Appear in the Voltage Equation for Parallel Circuits?

    I don't understand how I comes into play in the four equations. For example, in V = (I + I1)R, shouldn't it just be V = I1R? Or V = (I(component through bottom wire) + I1)R? Any help would be greatly appreciated. Thanks!
  19. L

    What's the equivalent resistance of this circuit?

    This was on my physics exam today and I couldn't solve it. Switch (two red dots) was originally open, and when it was open, the capacitor is uncharged. Then the switch was closed, and they asked me to find the time constant of the charging process. I couldn't find the time constant because I...
  20. S

    Equivalent Resistance: Series or Parallel Triangles?

    Homework Statement Okay. I thought I knew how to do these type of questions, but here goes. The node at a is attached to the positive terminal of a voltage source and c is attached to the negative. I'm completely bemused as to how to reduce this circuit into a single-resistor equivalent...
  21. A

    Finding the equivalent resistance

    Homework Statement Find the equivalent resistance of the following circuit as seen from terminals a and b. Homework Equations For resistors in series we can sum their values; For resistors in parallel we use R_{eq} = 1 / (1/{R_1} + 1/{R_2} + ... 1/{R_n )} The Attempt at a Solution I don't...
  22. S

    Equivalent Resistance: To Include or Not to Include r5 and r6?

    Homework Statement Trying to find equivalent resistance between points a and b.Dont know whether to include resistances r5 and r6. Thanks Homework Equations The Attempt at a Solution Im not sure what to do with the resistances r5 and r6in the open circuits are they apart of...
  23. A

    Equivalent resistance of tricky circuits?

    equivalent resistance of tricky circuits? Homework Statement what is the equivalent resistance between A and B? Homework Equations kirchoffs law for voltage and current The Attempt at a Solution i got the equivalent resistance between A to C as 3R/4 but i have to find the...
  24. G

    Equivalent Resistance of a Ciruit

    Homework Statement Find the equivalent resistance of the circuit as shown in the diagram below; where, R1 = 2 Ω, R2 = 1 Ω, R3 = 2 Ω, R4 = 1 Ω, R5 = 4 Ω, R6 = 4 Ω, and R7 = 4 Ω. http://i.imgur.com/OsAs2.gif Homework Equations The Attempt at a Solution R3 and R4 are in parallel...
  25. R

    Equivalent resistance with possible short circuit

    Homework Statement Find the current flowing through the voltage source in mA. Assume Vs = 3.9 V and R = 8.3 kohm. Round off your answer to two decimal points. Homework Equations 1/R(equivalent) = 1/R1 + 1/R2 + ... I=V/R Kirchoff's voltage law The Attempt at a Solution I considered the 3...
  26. 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.)...
  27. B

    Equivalent Resistance and Branch Currents in Non-simple Circuits

    I'm asked to find an equivalent resistance and the current through each branch of the following circuits. (r is a fixed arbitrary value for all resistors in the circuits) Homework Equations V=IR Sum of I at a node = 0 Sum of V about a closed loop = 0The Attempt at a Solution I've been playing...
  28. M

    Engineering Finding Equivalent Resistance in a Circuit

    Homework Statement The problem wants me to find the equivalent resistance at the terminals. Here is the circuit plus some of my work. The Answer according to the teacher is C. http://i.imgur.com/JaW7f.jpg Homework Equations The Attempt at a Solution As seen from my work, I added...
  29. R

    The Equivalent Resistance Calculation

    Homework Statement What is the equivalent resistance between points a and b: [PLAIN]http://img706.imageshack.us/img706/8615/circuitq.jpg The Attempt at a Solution The correct answer is Req=25 Ω. Looking into the circuit the 20 Ω is in series with the 10 Ω which is in parallel with...
  30. D

    Simple Thevenin equivalent resistance problem

    Gentlemen. Homework Statement Calculate the Thevenin equivalent resistance. Homework Equations Rseries - Rtot = R1 + R2 + ... + Rn Rparallel - Rtot = 1/(R1^-1 + R2^-1 ... + Rn^-1) The Attempt at a Solution As the picture shows, The second ohm-meter tells me 5.7 Ohms is...
  31. N

    Checking if equivalent resistance is right

    Homework Statement Homework Equations The Attempt at a Solution
  32. N

    Engineering Need help finding equivalent resistance in a circuit.

    Homework Statement Homework Equations delta wye transformations? The Attempt at a Solution I feel like I should do delta wye transforms here, but that doesn't really lead me anywhere. Am I missing how I should do the problem?
  33. L

    Electric Circuit - Equivalent Resistance

    Homework Statement For 1 and 2 : Find the equivalent resistance for the resistor network provided Homework Equations For resistor in series : Req = R_{1}+R_{2}+...R_{n} For resistors in parallel : Req = (1/R_{1}+1/R_{2}+... 1/R_{n})^{-1} The Attempt at a Solution For...
  34. P

    Find the equivalent resistance for the circuit in the figure.

    Homework Statement Find the equivalent resistance for the circuit in the figure. (Use the following as necessary: Vemf, R.) Homework Equations V=IR The Attempt at a Solution This problem isn't that hard, but I'm having trouble trying to visualize how to combine the resistors. The...
  35. Z

    Equivalent resistance between points a and b

    Homework Statement I don't know where to start. Can anyone recommend a book the instructor didn't assign one.
  36. J

    Find the equivalent resistance in a circuit

    Homework Statement Find the equivalent resistance in the circuit below: Homework Equations The Attempt at a Solution I know the two 4 Ohm resistors (on the same wire) are in series and thus add to 8 Ohms. However, I do not know where to go from here. When the resistors are in a...
  37. F

    Obtain the equivalent resistance at the terminals a-b

    Homework Statement [PLAIN]http://img593.imageshack.us/img593/6015/251a.png Homework Equations for combining resistors in series: R1 + R2 for combining resistors in parallels: R1R2/(R1 + R2) The Attempt at a Solution I've tried redrawing the circuit many times trying to make it easier to...
  38. B

    Derive a formula for equivalent resistance

    Is it possible to derive a formula for the equivalent resistance of n such sections in cascade? Show your analysis. Series: Reqv = R1 + R2 +...Rn Parallel: Reqv = 1/{(1/R1) + (1/R2) + (1/R3) +...(1/Rn)}
  39. Z

    Calculating Equivalent Resistance in a Hexagonal Prism Circuit

    Homework Statement All the wires on the front and the back hexagonal face (of the Skelton hexagonal prism) have resistance R. All the wires along the lines joining the vertices of two hexagons have resistance 2R. The equivalent resistance between P and Q as shown in the figure is The...
  40. M

    Equivalent Resistance: How to Rank Resistors from Highest to Lowest

    The question was to rank from highest to lowest equivalent resistance. This is what I came up with, but it was counted wrong and I don't understand why. http://i324.photobucket.com/albums/k327/ProtoGirlEXE/100_0687-1.jpg The equivalent resistance of resistors in series are added while in...
  41. M

    Equivalent Resistance: Unravel the Mystery

    http://xkcd.com/356/ I'm clueless, yet curious.
  42. A

    Equivalent resistance of a purely resistive network

    Homework Statement Calculate the equivalent resistance between the points X1 and X2. Homework Equations R series = sum of resistances R parallel = reciprocal of resistances The Attempt at a Solution I'm sorry I do not get any idea on solving the question. I have done it in the...
  43. P

    Calculating Equivalent Resistance

    Homework Statement In the circuit shown in the figure, R1 = 3.23 Ω, R2 = 5.19 Ω, R3 = 23.1 Ω, and V = 10.7 V. a) Determine a value for the equivalent resistance. http://img651.imageshack.us/i/p074figure.png/ Homework Equations Parallel is 1/R1+1/R2+1/Rn=1/Req Series...
  44. K

    Equivalent Resistance of a Ciruit

    1. Find the equivalent resistance of the circuit as shown in the diagram below; where R1 = 1 Ω, R2 = 2 Ω, R3 = 2 Ω, R4 = 4 Ω, R5 = 1 Ω, R6 = 1 Ω, and R7 = 2 Ω. http://img21.imageshack.us/i/prob06v2.gif/ http://img21.imageshack.us/i/prob06v2.gif/Homework Equations R(parallel) 1/R(total) = 1/R1...
  45. S

    Equivalent resistance in this network

    http://img571.imageshack.us/img571/3774/circuitb.png Uploaded with ImageShack.us For my a level homework i have to find the equivalent resistance in this circuit, i don't want anyone to do my homework i would just like to be pointed in the right direction. We have been doing a bit about...
  46. P

    What is the equivalent resistance across points a and b?

    1. find the equivalent resistance across points a and b The Attempt at a Solution I've used kirchhoff junction and loop rule to get a whole chunk of simultaneous equations but i can't seem to lay the finisher. Assigning I_1 to I_4 in the clock wise manner starting from the 5...
  47. T

    Engineering Find equivalent resistance in this circuit?

    Homework Statement Find the equilivant resistance in the wheatstone bridge circuit. Here is a picture: http://sub.allaboutcircuits.com/images/00485.png Homework Equations The Attempt at a Solution I know R1 and R2 are in parallel and R4 and R5 are in parralel but I'm getting confused with R3...
  48. D

    Find Equivalent Resistance Across Rab: A Geometric Conundrum

    Homework Statement Find the equivalent resistance across Rab Homework Equations Series: Req=R1+R2...Rn Parallel Req=(R1 * R2 *...Rn) / (R1 + R2 +...Rn) The Attempt at a Solution its the geometry that is throwing me off in this problem. Starting on the left side, I want to put...
  49. B

    What is the Equivalent Resistance between Points A and B in this Circuit?

    Homework Statement The equivalent resistance between points A and B of the resistors shown in the figure is 27Ohms. Find the value of resistance R. Here is the diagram: http://session.masteringphysics.com/problemAsset/1122575/1/Walker.21.36.jpg Homework Equations Rseries =...
  50. Saladsamurai

    Circuits: Draw Equivalent Resistance

    Homework Statement Man, I stink at circuits. I have to simplify the 1st circuit in the image below to an equivalent resistance. I am almost there, but I am unsure of how to relate the remaining 3 resistances. In the drawing, a subscript Ri||j denotes the equivalent resistance of the two...
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