What is Polarity: Definition and 164 Discussions

Electrical polarity is a term used throughout industries and fields that involve electricity. There are two types of poles: positive (+) and negative (−). This represents the electric potential at the ends of a circuit. A battery has a positive terminal (+ pole) and a negative terminal (− pole). Interconnection of electrical devices nearly always require correct polarity to be maintained. Correct polarity is essential for the operation of vacuum tube and semiconductor devices, many electric motors, electrochemical cells, electrical instruments, and other devices.

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  1. Nile Anderson

    How do you determine the polarity rods placed in a solenoid?

    Now well the question is pretty straight forward , and please do not pass this by , I am in high school but I am a still a very accomplished physics student. I am currently doing Magnetism and I came by a question , where people are saying a solution that seems very counter-intuitive to me...
  2. Quotes

    Equivalent Emf in case of polarity being changed

    I read the following statement in a book: "if polarity of m number of cells out of total n number of cells are connected in series with external resistance R is reversed then equivalent emf of such combination of cells is given by Eeq= (n-2m)E (where, each cell has same value of emf= E" I...
  3. L

    Pharmacophore and polarity of aspirin and ibuprofen?

    Homework Statement I need to know the pharmacophore of aspirin (acetylsalicylic acid) and ibuprofen. There is a task where I have to compare these two drugs' structure, synthesis, mechanism of action and side effects. Specifically, it says to include, "The chemical structure of the drug...
  4. O

    What is the polarity of a Pn junction diode

    Hello all Textbooks teaches us that in the formation of Pn junction in between P and N type semiconductor a region is formed where free electrons of N diffused in P side and exhaust by the holes of P near the junction. Such a region becomes devoit of free charge careers and their are only ions...
  5. D

    Understanding Coil Winding Direction & Polarity

    So I've been told that the direction that you wind a coil will determine the polarity of the induced voltage across the coil. I drew out two coils with clockwise and counterclockwise winding direction and with using the right hand rule and saying that the positive polarity of the induced...
  6. Jewish_Vulcan

    Understanding Voltage Dividers: Polarity and Voltage Reduction

    What polarity does the output of a voltage divider have?, do the resistors only decrease the original voltage?
  7. U

    Diode Polarity: Anode, Cathode, Forward Bias

    What is meant by diode polarity. If we do connect anode to positive and cathode to negative then its means it works on Forward Bias mode. I think positive means higher potential than negative, in other words, if positive terminal which is Anode is to be at 5 volts and negative terminal which is...
  8. C

    Determine if a Molecule is Polar - Steps & Tips

    Hi, I know what are the steps to determine if a molecule is polar or not, but I'm having one small problem. When I have determined teh geometrical shape of my molecule and drew the vectors of the polar bonds that goes from the least electronegative atom to the most electronegative atom, how...
  9. M

    Is there a difference in polarity between maleic acid and fumeric acid?

    I was wondering because I did a TLC experiment where maleic acid has a RF of 1.4 and fumeric acid has an Rf of 4.5. Everywhere says that a longer Rf means that the solvent is less polar than a smaller Rf solvent. However I read somewhere else that Maleic acid has the same polarity as fumeric...
  10. H

    Quickly switching electromagnet polarity. Inductance issues?

    Hello all, There are a million threads and a million Google hits out there on the topic of switching the polarity of an electromagnet. Very simple stuff. But none seem to touch on the issue of inductance. I am building a small linear actuator that will be a coil wrapped around a thin plastic...
  11. S

    Exploring the Limits of Polarity Switching Speed in Electromagnets

    I'm not sure if this is in the right section but...Is there a limit to how fast the polarity can be switched on an electromagnet? If there is a limit then how fast can they be switched? Thanks.
  12. Q

    Polarity of the Binary Halogen Acids

    Does the polarity of the binary halogen acids increase or decrease down the group? I have one argument for decrease based solely on electronegativity considerations. I have one argument for increase based on orbital overlap and electron density. Taking electron density in an orbital to be...
  13. L

    How can Voltage have polarity? How can they be negative or positive?

    Voltage is potential difference between two terminals of a power source that causes the electrons to flow, right? How can that be positive or negative? What is positive voltage and what is negative voltage? Thank you,
  14. C

    How can polarity of AC inverse but keep the live hot and neutral cold?

    In an AC circuit, we know that the polarity inverses, and what i know is that the flow of current also will therefore inverse.. which means that the live will become negative and the neutral will become positive.. What i can't understand is how the polarity inverses but the live is still the hot...
  15. M

    What is the difference between a dipole and polarity?

    From what I have been learning recently, a dipole is a separation of electric charges and in chemistry, a dipole refers to the separation of charges within a molecule between two covalently bonded atoms (which is caused from one atom having a higher electronegativity) What I don't understand is...
  16. S

    How to Determine the voltage polarity of inductor in a circuit?

    The Voltage polarity across the inductor is same as that across the capacitor since both are in parallel and the voltage across them must be same. But when Inductor, capacitor and resistor are connected as shown in the second figure what would be the voltage polarity across the inductor and...
  17. A

    Polarity of 3p core transformer

    I have a 380V,3 phase core type transformer which is being used as AC line choke in the incomer of a VFD.As we are using only the inductance property of the transformer,I was just wondering whether we could connect R phase of the supply to any winding and then follow the phase sequence...
  18. harjot singh

    Polarity in Atoms: Understanding Electron Movement in Covalent Bonds

    here polarity in an atom is although chemistry topic but my problem is related to QM my question is that how electrons revolve around the covalently bonded atom where the electrostatic forces of attraction causes them to stuck at a single point. but if this assumption is wrong then correct me...
  19. DaTario

    Neon Lamp Polarity Measurement

    Hi All, I would like to know why the neon lamp is used to measure electrical polarity. What is the working mechanism involved. Best wishes, DaTario
  20. P

    Two opposite polarity charged capacitors in series

    Homework Statement Homework Equations Q=CThe Attempt at a Solution a) I want to say that since both have the same potentials then it is similar to a parallel circuit where the charges can differ on each capacitor. If i think of point A as an input and point B as an output then the potential...
  21. S

    Magnets and their polarity - what would happen if

    If I were to take 2 neodymium magnets, and lay one down on the table, and stand the other on its end on top of it (resembling an upside-down T), would they attract, repel, or be neutral? Two poles of the standing magnet against the single pole that is facing up... what would the outcome be? I...
  22. S

    Positive or Negative? A Question about Polarity

    Referring to following image, Does anyone have any suggestions on which side is positive polarity? Thanks in advance for any suggestions :>
  23. S

    Does ACE IMF Polarity Come from Bz Data?

    IMF Polarity Predictions: Comparison of real-time ACE IMF polarity data (solid black line) with Wang-Sheeley-Arge model predictions (colored dots). The three sets of predictions (i.e., red, green, and blue dots) are based on data from, respectively, Wilcox (WSO), Mount Wilson (MWO) and SOLIS...
  24. S

    Effect of Solvent Polarity on Rf Value in TLC

    How does polarity of the solvent affect the Rf value? I was going over a problem in my book that said that polarity would increase the Rf value of both the polar and nonpolar analyte due to increased solubility. This doesn't make sense to me because wouldn't the solubility of the nonpolar...
  25. S

    What causes differences in polarity between alcohol and ketone molecules?

    What is the relationship between polarity and hydrogen bonding? I have come across several problems saying that an alcohol is more polar than a ketone because of hydrogen bonding but I don't see the relationship between these two. Intuitively, I thought ketone would be more polar because it has...
  26. S

    Polarity of Nitrate: Exploring Factors and Debunking Misconceptions

    Is nitrate a polar or non-polar molecule? I understand that it has a trigonal planer shape (and therefore it has symmetry) but should we also consider the double bond (do multiple bonds destroy symmetry)? I assume it would be polar because it is SOLUBLE in WATER, however, after viewing many...
  27. C

    Can electric shaver charge batteries installed with reversed polarity?

    Hi, I bought 2-AA (with pins tabs) rechargeable batteries for a Braun electric shaver. Checked the polarity of the old batteries, marked it on the board, and soldered the new batteries accordingly. (In series.) First charge lasted 4 weeks. Next 3-4 charges lasted less and less. Now...
  28. Y

    How to proof the polarity of the reflected wave of Oblique incident.

    As shown in the attachment, the book assumes ##\hat E_{||}^r=\hat y_r=(\hat x \cos \theta_r +\hat z \sin\theta_r)##. Why? How do you proof this. I have another post here about the Normal Incidence and no luck. I am not even convinced that the reflected E is even in the Plane of Incidence, how...
  29. Y

    Problem with proofing polarity of the reflected and transmitted wave.

    This is an exercise problem, BUT my question is not the exercise, but the fundamental assumption of the problem. That's the reason I don't post it in the homework section as it has nothing to do with solving the problem. I have issue with the given assumption all together. This is a case of...
  30. X

    Voltage Vector/Scalar Components, SI Units, Direction and Polarity.

    All, please help me refine, restate, explain, understand, expand, add, remove, answer the below statements/ questions. Thanks in advance. 1.) Voltage is considered a scalar quantity. (J/C in SI Derived Units) which is a magnitude of energy per coulomb...no direction with this example. Some...
  31. F

    Direction of the induced current and polarity

    Homework Statement http://img805.imageshack.us/img805/6030/82154948.png Find Vemf (between points 1 and 2) and it's polarity at t = 0. I have omitted details because my question is specifically on the polarity.Homework Equations Lenz's law: An induced electromotive force (emf) always gives...
  32. N

    Flipping the polarity of a compass needle. Why does this work?

    Awhile back I had been messing around with batteries, copper wiring, compasses and small neodymium magnets; during this time I figured out how to flip the polarity of a compass needle. The most reliable way was to hold the two magnets above the compass needle and force, as best I could, the two...
  33. F

    Reverse polarity protection circuit. Help with component values?

    EE is not my forte. Although this little circuit is so simple that I could get myself 90 percent there, it performs such an important function that I would like to get it more like 99 percent correct. I want to add the circuit to this board...
  34. Y

    Determine the polarity of the reflected EM wave.

    Attached are the drawings. Does the polarity Eof depend on \Gamma =\frac {\eta_2-\eta_1}{\eta_2+\eta_1} So if \eta_2<\eta_1, the Γ is negative and the polarity of the reflected wave is opposite polarity? I understand \theta_i=\theta_r and all that. As shown in the drawing, if you look at...
  35. Τ

    Polarity of Tetraphenylporphyrin?

    Homework Statement What is its polarity of a molecule of Tetraphenylporphyrin (TPP) as a whole? 2. The attempt at a solution Given the structure of TPP, there is a ring inside that contains two N-H bonds across from each other and two nitrogen atoms with lone pairs across from each other...
  36. J

    DC Reverse polarity protection using P-MOSFET

    Hello All, I'm designing a circuit board that needs to run on a 12VDC supply and will need to supply a fair amount of power to drive a bunch of 12V relay coils, in addition to some electronics. Since I want to keep the voltage drop on the supply a small as possible, I thought about using a...
  37. D

    Polarity switching electromagnet

    I want to make an electromagnet to rapidly switch polarity back and forth. I hear the core should be made of laminated iron to avoid heat losses; is this correct? Where could I get one such core from, and is there anything else I should consider?
  38. AakashPandita

    Polarity in water molecule and electronegativity of oxygen in that molecule.

    H20 is polar in nature. It is fundamentally because oxygen is more electronegative than hydrogen and the shared electrons tend to be near oxygen. This may be because the atomic number of oxygen is more than that of hydrogen. But in the bond I don't understand how the 2 shared electrons...
  39. johann1301

    Circuit with 2 batteries when one has a reversed polarity

    What happens if you take let's say a 12 volt battery and connect it to a lightbulb(not LED). Well... the lightbulb lights up obviously! But then connect a 6 voltage battery also(in series), but with reversed polarity (against the current that is). What happens then? Will there be a shortage...
  40. T

    Current, Polarity and EMF through circuit?

    Homework Statement In the circuit shown in the link, the 6.0 \ohm resistor is consuming energy at a rate of 24.0 J/s when the current through it flows as shown. A) Find the current through the ammeter A. B) What is the polarity and emf of the battery \epsilon assuming it has negligible...
  41. P

    Is Polarity Universal? Examining Forces & Particles

    Outside of gravity, is polarity seen in all the other forces, particles, fields, etc.?
  42. L

    How Do Solenoid Polarities Affect Magnetic Field Patterns?

    Homework Statement A current is passed through two solenoids placed in close proximity to each other as shown in the figure attached. Reproduce the figure showing the polarity of the two solenoids and the magnetic field pattern for the arrangement shown. Homework Equations There isn't...
  43. D

    Switching polarity on electromagnets

    First off, hi, I'm new. Sorry if this is not the right board; I was unsure between Classical Physics, maybe Quantum since this involves fields, or Electrical Engineering. On to the question, say you have an electromagnet with an iron core. As I understand it, a magnetic field acts on a...
  44. A

    Find out polarity of device for using ac-dc adapter

    I have a audio recorder (Edirol R-09HR High-Resolution WAVE/MP3 Recorder) need to use ac-dc adapter. There is no any marker to tell me polarity of input in this device. (I check the adapter from amazon.com for this device which I do not have, there is no marker as well) I have a Radio-Shack...
  45. P

    Polarity of large CHO compunds

    Hello! Does anyone have information or knowledge on the polarity of larger CxHyOz compunds? To be more specific, the compunds that I'm interested in are different kinds of lignans such as Hydroxymatarésinol (C20H22O7) and tannins such as taxifoline (C15H12O7) just to name a few. As I...
  46. F

    Differential Readings upon Reversing Polarity on MEMS Gyroscope

    Hi, y'all; This will likely be a simply question for most of you, but I am still something of a neophyte (yes, yes, starting off with the whole education thing in my 30's -- egad!) but if I were to reverse the current running through a MEMS gyroscope, what would be the outcome in the figures...
  47. A

    Polarity of a horseshoe shaped solenoid

    Homework Statement polarity of a horseshoe shaped solenoid given symbol for power source large line small line. Current flows through the right end of the horsehoe and out of the left end. The wire is wrapped in a CW direction if looking at the left end of the magnet. The wire is...
  48. S

    Polarity of Induced EMF in a Conducting Ring

    I have a question regarding a conducting loop of radius r in a changing magnetic field B. I understand and can determine the direction of the induced current which implies the existing of an electric field that is tangential to the loop. Since this is a closed loop, I am having trouble...
  49. J

    What is the Effect of Connecting a Load on the Polarity of Induced Voltage?

    Homework Statement This is seriously going to drive me insane. I know that a time changing B field produces a curling E field. For case #1, I have an open circuited loop with a B field increasing out of the page. This should create a polarity indicated in my picture. I hook up a load...
  50. B

    Does bond polarity affect bond strength and length in covalent compounds?

    I have some confusion about the relationship between bond polarity and bond length. Generally strong bonds are short in length. Generally strong bonds are more polar. (Ionic bonds are stronger than covalent bonds). Therefore, the more polar bonds tend to be shorter in length? And yet...
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