What is Potentiometer: Definition and 105 Discussions

A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.
The measuring instrument called a potentiometer is essentially a voltage divider used for measuring electric potential (voltage); the component is an implementation of the same principle, hence its name.
Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a mechanism can be used as position transducers, for example, in a joystick. Potentiometers are rarely used to directly control significant power (more than a watt), since the power dissipated in the potentiometer would be comparable to the power in the controlled load.

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  1. H

    Calculating EMF of a cell using Potentiometer.

    Hello, I'm having a bit of a hard time understanding the concept of calculating the emf of a cell (e1) By connecting it to a potentiometer. the thing where I am getting confused is why do we connect the cell as in -++- And not -+-+. Kindly help
  2. D

    Using a potentiometer to constrain voltage between -9 and 9V

    I am stumped on a problem I have been working on. I am told to build a circuit that will have an output voltage between -9 and 9V. We are given two 12 V batteries as power sources, and a choice between 3 potentiometers with values of 10k ohm, 20k ohm, and 50k ohm. We are allowed to use any...
  3. E

    The way the potentiometer measures

    I may have a misconception about the way the potentiometer measures thermal emf... (Seebeck effect... Fe,Cu...the two points where these two wire are connected are at different Temperature... So there is a voltage difference between the two points...) When we are to measure the E,we need to...
  4. J

    Resistive Wire Selection For Linear Potentiometer

    I'm trying to build a ball and beam balance control system. I was thinking of using a metallic ball and two wires to make a linear potentiometer to give the ball's position. I'm not sure what to use as the resistive wire. Most wire I find doesn't seem to provide a sizable amount of resistance. I...
  5. A

    Stretched wire potentiometer, Conceptual help

    I am having problem understanding the working of Stretched wire potentiometer. Now the book says that the potential of a and A are same because the wire Aa has negligible resistance. That is were the problem comes for me. Suppose the batter connected to AB be of 10V (assume negative terminal...
  6. L

    How to determine the position of the slider on a potentiometer

    Homework Statement This circuit shows a 10Kohm potentiomiter with a 5Kohm load. determine the position of the slider on the 'pot' when the voltage acreoss points 'xx' is 3V ok so the 10K resistor is a potentiometer which is a variable resistor, so what they are asking when they say...
  7. K

    Archived Balanced length of a potentiometer wire

    Homework Statement A battery if emf E0=12v connected across a 4m long uniform wire having resistance 4Ω. The cells of small emf E1=2v and E2=4v having internal resistance 2Ω and 6Ω respectively, are connected as shown in figure below. If galvanometer shows no deflection at the point N, then...
  8. A

    Why Does a Galvanometer Show Zero Deflection Despite Potential Differences?

    Potentiometer conceptual help! The book that i am using currently states that "If the potential difference between A and J is equal to the emf of the cell, no current flows through the galvanometer. It shows zero deflection." But suppose A be at 10V and J at 5V, and The +ve terminal of battery...
  9. E

    Simple Circuit analysis of potentiometer problem

    Really simple problem but: If you have a circuit with a power supply, a potentiometer and an output voltage taken from midway down the potentiometer and just after it; would this act like a potential divider with the potentiometer acting as two resistors?
  10. Femme_physics

    Can I convert a potentiometer to 2 resistors?

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

    Where can I find a Potentiometer Panel-mount, single-turn, 2K linear

    Hi guys I live in the UK and I was wondering if any of you knew a place where I could get hold of a Potentiometer Panel-mount, single-turn, 2K linear, 0.1 min. And it need be no more than 0.5w. The reason for this is because I can't find one on the internet in the UK without excessive postage...
  12. D

    The type of network involving potentiometer

    Homework Statement Adjust the potentiometer to get V_{0} = 0 V(V_{a} - V_{b}). What is this network called? Homework Equations The Attempt at a Solution I'll be honest. This professor didn't even prepare for the lab and decided to do lab about the potentiometer we didn't even...
  13. F

    Potentiometer : how that balancing point is reached?

    When potentiometer is used to measure and compare emf of cells, how that balncing point is reached?... this is the circuit diagram what i mentioned.. in the description it is said that at that balancing point (current through that galvanometer shows zero), potential drop across AC is equal...
  14. C

    Position Potentiometer for 3V Across XX

    A circuit has a 10 kΩ potentiometer with a 5 kΩ load. Determine the position of the slider on the ‘pot’ when the voltage across points ‘XX' is 3 V. Think I'm there but not sure of my working out is excessive or I've taken the long route R1 in series with 2 resistors in parallel (R2 and...
  15. R

    Position of slider on potentiometer

    Homework Statement The circuit (attached) shows a 10kOhm potentiometer with a 5 KOhm load. Determine the position of the slider on the 'pot' when the voltage across points 'XX' is 3V. Homework Equations Vout = Vin* (R2/(R1+R2)) The Attempt at a Solution Please see attachment...
  16. V

    Potentiometer vs Voltmeter.Which should be preferred for greater accuracy?

    I want to find out the potential difference between two given points with maximum accuracy. Which one should i choose and why. I think both will work fine in most of the cases.
  17. S

    Understanding Op-Amp Gain with Potentiometer Configuration

    Homework Statement Here's the network: R1=100 The gain ranges from -1V/V ---> -10V/V and the potentiometer R4=10. Is R4 and R3 in parallel with each other? I can't seem to get the right answer... Moreover, this is what was done: -(R2/R1)(1+(R4/R2)+(R4/R3))=-10 Can someone...
  18. B

    Voltage across a potentiometer?

    The circuit of (attached file) shows a 10 kΩ potentiometer with a 5 kΩ load. Determine the position of the slider on the ‘pot’ when the voltage across points ‘XX' is 3 V. I can't figure out how you would find the current first without knowing total resistance? Any help would be greatly...
  19. R

    Very High Voltage potentiometer

    Hello. I need 3 adjustable HV power supplies (0-10 kV). I built one and as currents needed by the 2 others are very low (in the order of 1 µA). I try to avoid building PS #2 & #3. That means that I'm looking for a device which looks like a kind of HV potentiometer but of course which is not one...
  20. R

    Controlling motor speed with a potentiometer

    I'm trying to control the speed of a DC motor by using a potentiometer, but am unsure what value resistance I should use. Having tried 500k, 10k and 500ohms, the motor stalled almost as soon as I turn the dial (a bit more leeway with the 500ohm but not much)...
  21. C

    Creating a fan control via a Potentiometer

    Hi, I wanted to create my own computer fan control and bought a 100ohm potentiometer. I have hooked the pot as shown in the picture except that it is in the yellow wire (+12V) and not the red one (+5V) , black is ground. The fan will start at full speed and doesn't change one bit if I...
  22. D

    Potentiometer to measure cell voltage

    Homework Statement http://meinprojekt.hostzi.com/images/Picture2.jpg We did an experiment to measure E mf or the cell voltage of bateries. A thin wire (slide-wire potentiometer) is connected into the circuit. From point a to c the resistance along the wire is 36 Ohm. Depending on where the...
  23. F

    DAC based digital potentiometer

    http://img851.imageshack.us/img851/2991/captureyd.jpg To start off, I understand that I can compute the current flowing through each of the ladder rungs, as I = Vin/((2^n)*100k), where n is the terminal ladder interested in. Doing so, I solved part a of the question for when the digital...
  24. L

    Extremely Difficult Circuit Problem involving a potentiometer

    Homework Statement The schematic below shows the simplest potentiometer that can be used to regulate the voltage supplied onto the electric load that has the resistance R. In such case, the variable resistance is made of the uniform piece of wire having total resistance R0 and length l and a...
  25. D

    Potentiometer Circuit Question: Understanding Electron Flow and Resistance

    Homework Statement The attached graphic shows a potentiometer circuit. The uniform wire AB is 100 cm long and has a resistance of 0.038 ohms/cm. The standard cell has an emf of 1.35 V. The galvanometer registers zero when the sliding contact is at L = 48.0 cm. If the sliding contact were moved...
  26. Saladsamurai

    Using a potentiometer to detect position

    I am reading up on this since it was suggested that I do this for a project. I am supposed to track the position of a steel ball on a beam as the beam is tilted up and down. Now unless I am mistaken, the potentiometer has to physically touch the entity whose position is to sense right? Or am...
  27. J

    Potentiometer as divider: How to use both sides of the split voltage?

    Potentiometer as divider: How to use both "sides" of the split voltage? Hello, I am building a custom electric vehicle using an existing controller and motor combo. The controller reads the voltage on two leads to control the speed of the motor and expects the voltages on the two leads...
  28. T

    How to Calculate the Series Resistor for a Potentiometer Measuring 2.5 mV?

    Homework Statement The slide wire of a simple potentiometer has a resistance of 5.0 ohm . The current source for the potentiometer is a cell of emf of 2.0V and of negligible internal resistance . Draw a labelled circuit diagram showing how the potentiometer might be used to measure an emf of...
  29. M

    Ideal potentiometer for post Op-Amp

    Greetings, I have built a theremin that runs an output to a Velleman Mono 7W Amp. From the amp it then splits 3 ways. 1 to a speaker. The other two run directly to the horizontal and vertical connections of a deflection yoke in a 12V CRT television. This system works. I have sound from the...
  30. J

    Electrolytic Capacitor and Potentiometer question

    Hey guys, I have two quick questions: Is the outside of an electrolytic capacitor conductive? (Should I worry about it touching some other circuit components)? I have a 5kOhm potentiometer that for some reason began to smoke once while testing a circuit. I powered off the circuit and...
  31. D

    Choosing the correct potentiometer

    hello to all. I'm new here and hoping that I'm in the correct forum. my question is: I'm desiging a hoist to use as a strength tester at my job. I am using a winch that uses DC current. The motor is 1.3 hp using a 12v battery with line speeds of around 10.8 ft/min to 8.2 ft/min. I need to slow...
  32. Ivan Seeking

    Return-to-center potentiometer

    Does anyone happen to know a good supplier for an inexpensive, single-axis, return-to-center potentiometer, in the 5-10K range? Maybe I just keep missing it, but I am finding surpringly few options. What I am finding is surprisingly expensive. For example, Allied carries a rocker pot made by...
  33. U

    Voltage divider and potentiometer

    This is so far I've learnt...potentiometer is a potential divider, it also functions to measure the unknown emf of a cell (Ex). Here is the image of a potential divider: And here is one of a potentiometer: The thing that confuses me here is that if you compare both images, you will see...
  34. L

    MCQ: Potentiometer: Balanced Length, Resistance of Cell E

    Homework Statement In the potentiometer circuit shown,the balanced length l is reduced to l/2,when a resistor of resistance R is connected across the terminals of the cell E.The internal resistance of the cell E is (1) R/2 (2)R (3) 2R (4) 3R/2 (5) 3R...
  35. E

    Use of potentiometer or rheostat to determine resistance – need clarification

    Hello I understand Homework Statement 1) a potentiometer can be used to divide a voltage to any value between zero and the voltage source. This can be used to place a variable voltage through a resistor 2) A rheostat (variable resistor) which is placed in series with the resistance...
  36. Q

    Confused(HUGE misunderstanding) about potentiometer (HS physics)

    Hi everyone. I am extremely confused about how a potentiometer works. In my notes, this is the diagram. http://img25.imageshack.us/img25/5836/batteryu.jpg In the branch loop, there is no current. I know this is correct, but I am confused by it. Assuming the current flows clockwise...
  37. A

    Why Do Some Voltmeters Not Show 10V at Full Scale on a Potentiometer?

    The attached graph shows an experiment I performed where I had a potentiometer connected to a DC 10V supply, the voltage across the pot was measured with 5 different voltmeters of varying internal resistance. I guess the one with the highest internal resistance, to the order of 10megohm, is the...
  38. H

    Why is copper wire not commonly used in potentiometers?

    I’ve learned that copper wire is not generally used in a potentiometer. Is there any specific reason for this?
  39. M

    Engineering Solving Circuits with a Potentiometer: Calculate R & Rx for 1A-10A

    Homework Statement There's an 110V source and two resisters in series. The first resister, R, is a fixed resistor. The second resister, Rx, is a variable resister (a potentiometer). The potentiometer is to be designed to adjust current I from 1A to 10A. Calculate the values of R and Rx...
  40. M

    Potentiometer Use of Resistors

    Homework Statement I am uncertain how to provide a schematic, so I will ask a general question. Why would it be beneficial to use a larger resistor in a circuit using a potentiometer? Homework Equations The Attempt at a Solution
  41. J

    How a potentiometer can be used to measure an unknown emf?

    Could someone perhaps explain how a potentiometer can be used to measure an unknown emf? My book gives a bad explanation...
  42. F

    Feedback potentiometer circuit QUESTION

    Hi I just have a quick question for a feedback potentiometer circuit what is the purpose of the resistor R25? Please see circuit diagram below (attach) Thx a lot Fta_25
  43. T

    How do I calculate Vo/Vs for a potentiometer circuit with varying resistance?

    Homework Statement In the circuit below, the wiper divides the potentiometer resistance between \alpha R and\ (1- alpha R), 0 \leq\alpha \geq 1. Find Vo / Vs Homework Equations KVL KCL The Attempt at a Solution Im thinking that the Pot. Resistance will be R +(1-\alpha)R. Then to find the...
  44. F

    Potentiometer direct to mains for lamp

    Hi guys I'm new here and I require some help with a project I'm working on. I'm building a lamp prototype and i need to use a potentiometer to act as a dimmer. The pot needs to fit inside a 25mm ID tube, and is connected directly to the mains. First of all is this possible? I think I have found...
  45. T

    Choosing the correct potentiometer help

    Excuse me if I'm in the wrong forum for this question, as I'm new here. I'm building a set of speakers for my motorcycle and do not know how to correctly choose a volume control. The bike is 12V; the speakers are 4 Ohm; the amp is 150W max; an MP3 player will be the music source. Can anyone...
  46. B

    Simple potentiometer circuit help

    Hi ,please Can I have some suggestions to do this exercice: A simple potentiometer circuit used to measure unknown voltages accurately is shown below. Here Vs is the known source voltage, Vxis the unknown voltage, and the resistor is a variable one from which the values R1 and R2 can be read...
  47. †

    Using a Rotary Potentiometer and Float

    First off i'd like to say hi guys (and gals) - this may be my first post, but should hopefully be the first of many:smile: Basically i have a problem regarding some physics coursework. We're actually conducting these on the 8th of November - and i have a deadline of the 20th of November...
  48. T

    Measuring unknown emf by potentiometer

    in measuring unknown emf by potentiometer, why must the stable current source(working battery) have a voltage greater than any voltage to be measured? i can't understand why.. in our exercise in physics, we used a slide-wire potentiometer with the assumption that 1 meter of the slide-wire...
  49. N

    Maximum useage of a Potentiometer

    I am looking to create a set of racing simulator pedals, similar to these. I have identified the best potentiometer to use - http://www.betainnovations.com/hardware/downloads/157.pdf. As you can see the maximum range of the meter is 340 degrees. When the pedals are constructed the...
  50. N

    Why Does a Slide-Wire Potentiometer Require a Higher Voltage Battery?

    need everyone's help... pls. explain it to me for those who knows the experiment...thanks! 1) in measuring emf by slide-wire potentiometer, why should the working battery have a voltage greater than 2? why is the galvanometer polarity unimportant? 2)how is the function of a rheostat...
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