What is Resistors: Definition and 603 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

    Transistors acting as resistors

    From what I understand, transistors can be viewed as several things, one of which is a resistor. So how much resistance is a transistor turned on generally equivalent to? And what is normally considered a large or small resistance? I know voltmeters have a large internal resistance in...
  2. M

    Resistors in series and in parallel

    !20V battery.I need to Find Voltage, Resistance and Current in all resistors and total. This is what I did so far. Added 13ohms +15 ohms, then took all 3 of those and made it into one, whihc gave me 7.2258ohms. Did the same for the 72 and 45 to get 27.7 ohms. Then found the total resistance...
  3. M

    Resistors in seris and in parallel

    I have this question I need to Find Voltage, Resistance and Current in all resistors and total. This is what I did so far. Added 13ohms +15 ohms, then took all 3 of those and made it into one, whihc gave me 7.2258ohms. Did the same for the 72 and 45 to get 27.7 ohms. Then found the...
  4. J

    Circuit with two batteries and three resistors - Find current

    Homework Statement Find the current through R1, R2, and R3 for the attached diagram. Homework Equations Ohm's Law V=IR I=V/R etc.
  5. A

    Current when resistors are connected in series.

    So, I was studying about electricity and I came to the topic of connecting resistors(or resistances) in series or parallel... So the definition of resistors in series said that: Resistors are said to be connected in parallel if they are joined end to end and the same current flows through...
  6. N

    Check my work please? Circuit analysis, resistors in parallel, help

    Can someone check my work for me please? I'm pretty sure i made a mistake with the sign convention but I'm not sure which sources are supposed to be negative. help! Problem: http://imageshack.us/a/img201/339/circuitzz.png My solution: http://imageshack.us/a/img191/8049/circuitz.png...
  7. L

    Circuit help - resistors and batteries in a network

    circuit help -- resistors and batteries in a network Homework Statement (a) Calculate the current through each ideal battery in Fig. 28-41. (As a sign convention, assume the currents are "up" through each battery.) A (I1) A (I2) A (I3) Assume that R1 = 1.5 , R2 = 2.5 ...
  8. S

    How to wire given resistors to yield a total resistance?

    Essentially I have been given five resistors of strength 180 kΩ, 220 kΩ, 270 kΩ, 330 kΩ, and 390 kΩ and have been told to devise a way to wire these to produce a total resistance of exactly 206.421 kΩ. I have been working on this simply using a guess and check method and have had no luck...
  9. R

    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 = 73 Ω, R2 = R6 = 121 Ω R3 = 62 Ω, and R4 = 92 Ω. The...
  10. R

    Circuit with 2 Batteries and 6 Resistors

    Homework Statement [/B] 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 = 73 Ω, R2 = R6 = 121 Ω R3 = 62 Ω, and R4 = 92 Ω...
  11. G

    Circuit with Two Batteries and Six Resistors

    Homework Statement A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18.0 V and V2 = 12.0 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 64.0 Ω, R2 = R6 = 157.0 Ω R3 = 53.0 Ω, and R4 = 65.0...
  12. M

    Diodes in parallel with resistors and terminal PD

    1. Homework Statement The problem is not answering the questions, as supplied by the book The book then asks you to reverse both diodes, so you still have one diode in the circuit that let's current pass through it and one that does not. When you solve for the PD at Q you use the 0.6V...
  13. T

    Voltage Division with Multiple Voltage Sources Seperated by Resistors

    Homework Statement Find the voltage across the 10 ohm resistor. http://www.spacemonkeybrewing.com/images/circuit.jpg Homework Equations KVL - Sum of Voltages in a closed loop equal zero. Ohms - V=IR Voltage Divide - Va1 = (R1/(R1+R2...))Vs The Attempt at a Solution This is only...
  14. W

    Resistors in parallel and series

    Homework Statement Homework Equations resistors in series add resistors in parallel add inversally. the denominator of the answer(which is the fraction) will be your answer The Attempt at a Solution I added annotations to show my thought process this last part was a good tricky question...
  15. W

    Calculating Current in a Series Circuit

    Homework Statement Homework Equations I = E/(R sub_1 + R sub_2) The Attempt at a Solution So I tried using the same approach for part a and it did not produce the same result. here's what i did: I sub_2 = E sub_2/(R sub_2 + R sub_3) E sub_2 was given as 1.7V I sub_2...
  16. Q

    Which resistors should I use to generate a gain of 15 on an inverting amplifier?

    I have the set of values for resistors available: 10-12-15-18-22-27-33-39-47-56-68-82 And I need to get a gain of 15, which values should I use to get this? Also, I have a non-inverting amplifier, and again, I need a gain of 15. I selected the values: R2=12 and R1= 68+82+18=168 I assumed I was...
  17. S

    Finding the Current through Resistors - Kirchoff's Laws?

    Homework Statement http://session.masteringphysics.com/problemAsset/1003291/40/15092_a.jpg In previous parts of this problem, I solved that the current travels counterclockwise, and that I_A = \frac{2{\cal{E}}}{R_{2}+2R_{1}} . Homework Equations V= IR R[series,total] = (1/R1 + 1/R2 + 1/R3...
  18. 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...
  19. M

    Creating a small alarm using a capacitor, resistors etc

    1. The goal is to create a small alarm that goes off for exactly 6 seconds before turning off. The materials allowed are 1000 1 ohm resistors, wire, a box of rechargeable 1.5 V triple A batteries (12 count) and a piezoelectric buzzer. 2. Ohms Law. Power = V2/R 3. I have a design...
  20. trollcast

    Multiple resistors not in series / parallel

    Homework Statement Circuit as shown: (sorry about the amazing paint skills) The pd is being applied from A to B (C is in the centre of the circle) (1) Determine the relations between the current by reversing V and using symmetry or by any other suitable method (2) Calculate the total...
  21. Drakkith

    Voltage Drop in a Series Circuit with 100V & 2 50 Ohm Resistors

    Ok, let's say you have a 100v voltage supply and two 50 Ohm resistors in a series circuit. The total resistance is 100 Ohms, leading to a current of 1 amp. Now my question is, what exactly is voltage drop? I know the voltage drop across each resistor is 50 volts. If we were to look at one of...
  22. J

    Resistors in series - how can current be constant?

    I can't get my head around this: How can the current in a series circuit be unchanged by any amount of resistors? 1) I understand that there is only one path, and thus; 2) I understand that the charge isn't used up. BUT. If current is the charge passing a point per second, and resistors...
  23. F

    Kirchoff's rules & resistors in parallel

    Homework Statement Use Kirchhoff’s junction rule and loop rule (twice) to find the effective resistance of the two resistors connected in parallel as shown, and demonstrate that this agrees with the expression 1/R = 1/R1 + 1/R2 (poorly drawn picture of the circuit) The Attempt at a...
  24. P

    Adding Up Resistors: Order of Operations Explained

    I have added an attachment of the circuit for clarity. I initially began by assuming that the 13 ohm and 24 ohm resistors were in parallel and I got the Req for them. Then since the top resistor seemed to be in series with them I added its value. This is wrong of course, the correct sequence...
  25. Q

    Capacitor Resistors problem, , exam preparation

    Capacitor Resistors problem, URGENT PLZ, exam preparation Homework Statement In the following transient circuit, assume at t<0, the circuit is at steady state. Assume vc(t) is the voltage across the capacitor and v0 (t) is the output voltage as shown: Find (a) vc(0+) (b) vc(∞) (c)...
  26. J

    Preventing Hysteresis in homemade Force Sensing Resistors

    Hello, I am new to the forums and physics in general. I hope I am not posting in the wrong place. My understanding of physics in general is rudimentary at best, so please let me know if any of my statements are incorrect. I understand this is an extremely long post, so feel free to jump to...
  27. Q

    Engineering Circuit with Series and parallel resistors, voltage division rule

    Homework Statement Given: The power absorbed by the 15 ohm resistor is 15 W. Find R. http://sphotos-a.xx.fbcdn.net/hphotos-snc7/384382_495043340515186_1992745410_n.jpg Homework Equations parallel circuit for 2 resistor: Req =R1R2/ R1+R2 Voltage Division Rule: for series circuit VR2 =...
  28. D

    Confusion about combining resistors in series.

    Hello, everybody. I'm reading through my EE textbook and I'm having some confusion about when to combine resistors in series. The following figure is in my book: I see that they combine the parallel resistors of 6Ω and 3Ω to make the equivalent circuit shown in 2.42b. What I'm confused...
  29. U

    Engineering Solving a Circuit with Current Sources and Resistors

    Homework Statement The problem is attached below.Homework Equations The Attempt at a Solution I tried reducing the circuit by applying a source transformation to each pair of current sources and resistors. I reduced the CS and R at the upper left to an 8V source and 4-ohm resistor in series...
  30. S

    Circuit Problem with Resistors connected in parallel and series

    Homework Statement A circuit is constructed with five resistors and a battery as shown. The battery voltage is V = 12.0 V. The values for the resistors are: R1 = 76.0 Ω, R2 = 149.0 Ω, R3 = 169.0 Ω, and R4 = 121.0 Ω. The value for RX is unknown, but it is known that I4, the current that flows...
  31. C

    Kirchhoff's rules for resistors in parallel

    Homework Statement Use Kirchoff's rules to determine I1, I2 and I3 for the following circuit: Use the following values:ε = emf = 9 V r = internal resistance = 1.5 R1 = 5 R2 = 15 R3 = 13.75 Homework Equations The Attempt at a Solution I found I1 to be .9328 by adding all the...
  32. W

    Kirchoff's Equation w/ 2 Batteries and 4 resistors

    Homework Statement The circuit in the figure is composed of two batteries (ε1 = 9.0 V and ε2 = 5.0 V) and four resistors (R1 = 110.0 Ω, R2 = 40.0 Ω, R3 = 30.0 Ω, and R4 = 50.0 Ω) as shown. 1). What is the current I1 which flows through R1? 2). What is the current I3 which flows through R3...
  33. N

    Confusion regarding pulldown resistors.

    Hi, I am having some confusion regarding pull down resistors. In the schematic I have a 100k pulldown resistor. P1 is the output port and the nOE(OE bar) is the input to a buffer. What is confusing me is if the P1 input is high impedance then the nOE should go high, but when the P1 pin...
  34. 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...
  35. D

    Parallel Circuit: Current with 4 vs 3 Resistors

    Hey I came across this question in my textbook and the answer provided just does't make sense. A circuit consists of a battery and 4 identical resistors in parallel. The current in each resistor is 12 A. If one of the resistors burns out, what will be the current in each of the remaining 3...
  36. O

    Variable Resistor connected to parallel resistors

    Homework Statement In the electric circuit shown in the figure, when the value of the variable resistor R3 is 25Ω, the current which flows into the power supply is 2A. Moreover, when the value of the variable resistor R3 is 5Ω a current of 1A flows into the resistance R2. Q1.Find the value of...
  37. C

    A 9 volt battery is hooked up to two resistors in series

    1. A 9 volt battery is hooked up to two resistors in series. One has a resistance of 5 ohms, and the other has a resistance of 10 ohms. Several locations along the circuit are marked with letters, as shown above. If the voltage is zero at the negative terminal of the battery, the voltage at...
  38. M

    Why are the resistors in parallel?

    Resistor Rb1 and Rb2? How come?
  39. K

    Current through resistors in circuit with TWO ideal emfs

    Homework Statement In the figure, the ideal batteries have emfs 1 = 17.0 V and 2 = 0.5001 V, and the resistances are each 1.22 Ω. I tried to include a link but I am unable. As best as I can describe: There is one main loop with a wire connecting the bottom and the op piece. The two emfs are...
  40. B

    How would one connect three 9Ω resistors to get 12Ω?

    how would one connect three 9Ω resistors to get 12Ω?? Statement ----------- how would one connect three 9Ω resistors to get 12Ω?? equations ----------- i guess the relevant equations would be nothing more than series & parallel resistance connections.. The attempt at a solution...
  41. K

    Find the equivalent impedance of an infinite series of resistors and capacitors

    Homework Statement Find the equivalent impedance of the infinite series of resistors and capacitors as shown below -R----R----R----R----...R----... ____C____C____C____B_______C -r----r----r----r----...r----... Homework Equations 2.1. Equivalent resistance of resistors in series : R = R1 + R2...
  42. C

    Find the energy in a circuit, delivered to resistors, by battery, etc

    Homework Statement The circuit shown in the figure below is connected for 2.10 min. (Assume R1 = 6.00 Ω, R2 = 1.60 Ω, and V = 16.0 V.) (a) Determine the current in each branch of the circuit. *already did* (b) Find the energy delivered by each battery. (c) Find the energy delivered...
  43. A

    Basic LED circuit, 9v battery, what resistors to use?

    Hi all, I am a new guy to the forum, glad to meet you all. iv been doing a little rc project and now need to wire up some lights. iv never done circuit work before but I am willing to gain knowledge on how to. the main problem is that no matter how much i read or calculate, i cannot work out...
  44. K

    Solving for the currrents in the resistors

    I don't asnwer what to do with the wires crossing
  45. J

    Finding the current through an icosahedron of resistors

    Homework Statement Consider an icosahedron all of whose edges are 2 ohm resistors. If a 12 V battery is connected in opposite vertices, what is the current flow through each resistor? Homework Equations v=ir The Attempt at a Solution I found somewhere that the equivalent...
  46. C

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

    Homework Statement A coil of wire has 600 turns and is 5.5 cm in diameter is in a magnetic field that decreases from 2.2 T to 0 T in 6.2 ms. The axis of the coil is parallel to the field. The coil is hooked up to two resistors of 120 Ω and 200 Ω connected in parallel. What is the maximum...
  47. T

    Why same current flows through resistors in series?

    If two or more resistors are connected in series, isn't the current through each resistor supposed to be different due to their different resistances? But this does not occur. Is this because, if the drift velocity of the electrons through the different resistors were different, then charge...
  48. T

    Resistors, potential dividers and ohms law

    Here is my question: When I look a p.d divider circuit I get slightly confused, because the way I was reading the explanation it says: that when the a thermistors has 0 resistance it has 0V across, so when the resistance increase the voltage increases and the will turn on the base emitter to...
  49. S

    Resistors in Series with a lightbulb

    Homework Statement A lightbulb marked "75W at 120V" is at one end of a long extension cord in which each of the two conductors has a resistance of 0.800Ω. The other end of the extension cord is plugged into a 120V outlet. Find the actual power of the bulb. Homework Equations P = V^2/ R...
  50. C

    Is heat actually developed in resistors?

    We say that "heat is developed" in resistors when electric current flows through them..But we define heat as the tranfer of energy due to difference of temperature. So is saying that " heat is developed" technically correct?
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