What is Coils: Definition and 203 Discussions

An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. Some coils have an internal resistor, while others rely on a resistor wire or an external resistor to limit the current flowing into the coil from the car's 12-volt supply. The wire that goes from the ignition coil to the distributor and the high voltage wires that go from the distributor to each of the spark plugs are called spark plug wires or high tension leads. Originally, every ignition coil system required mechanical contact breaker points and a capacitor (condenser). More recent electronic ignition systems use a power transistor to provide pulses to the ignition coil. A modern passenger automobile may use one ignition coil for each engine cylinder (or pair of cylinders), eliminating fault-prone spark plug cables and a distributor to route the high voltage pulses.
Ignition systems are not required for diesel engines which rely on compression to ignite the fuel/air mixture.

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  1. R

    Engineering Short Circuiting 1 of 3 coils that are Wye connected

    For this question I'm focusing on part B 1. Homework Statement Three similar coils, connected in star, take a total power of 1.5 kW, at a power factor of 0.2, from a three-phase, 415 V, 60 Hz supply. Calculate: a) the resistance and inductance of each coil; b) the line currents if one of...
  2. C

    Two coils of wire with the same size and shape

    Homework Statement Two coils of wire that have same shape and dimensions are thickly rolled up so that the coincide, they only differ in number of coils (windings) N1 for the firs one and N2 for the second one (N1<N2). When there's constant current in the first one and there's no current in the...
  3. kolleamm

    Coils Winding Diagram for a P.M. Synchronius Motor 72 slots?

    Where I can find the coils winding diagram for a 3PH DC PMSM (Permanent Magnet Synchronous Motor) that has a stator with 72 slots for the windings? The same PMSM has a rotor with 8 PM's mounted on the rotor and a resolver's metal plate.
  4. C

    Why does number of coils on primary affect frequency?

    I'm reading a guide on how Tesla coils and slayer exciters work on this Instructable and it was speaking about how to fine-tune the Tesla coil in order to match the resonant frequency of the secondary coil. I understood it when it spoke about changing number of capacitors or the distance of the...
  5. F

    Are Tesla Coils really special?

    Hello, I have heard so much about Tesla coils in the context of wireless electricity. I think I understand how a transformer works: there are two metal coils, near each other. A time-changing current in the primary coil generate a time changing electromagnetic field that is captured by the...
  6. Dewgale

    Proving Uniform Magnetic Field with Saddle Coils

    Homework Statement We have seen that a long solenoid produces a uniform magnetic field directed along the axis of a cylindrical region. However, to produce a uniform magnetic field directed parallel to a diameter of a cylindrical region, one can use saddle coils. The loops are wrapped over a...
  7. K

    Induction: How Nearby Coils Generate Current

    why is current produced in a coil if it is placed near other current caarrying coil
  8. D

    Finding the resistive force of a magnet moving along coils

    Hi everyone! I posted this in the ME section as well but thought this would be a good section as well. I am working on a thesis project and have a question for anyone who feels they can answer it. I am trying to find the resistive force created when a magnet moves along a coil of wire. I have...
  9. D

    Finding resistive force from a magnet moved over coils

    Hi everyone! I am working on a thesis project and have a question for anyone who feels they can answer it. I am trying to find the resistive force created when a magnet moves along a coil of wire. I have put pictures below but here is the short explanation: The pendulum, which is fixed at a...
  10. J

    Setting up an LRC series circuit with coupled coils

    Homework Statement I have been trying to set up an LRC series circuit where in place of an inductor we have a pair of coupled coils. My aim is to determine the resonant frequency in the circuit when the voltage across the resistor or the current in the circuit is at a maximum. I am using a...
  11. K

    Hysteresis in helical coils springs

    Hi, Do helical springs have hysteresis. Say I do an exercise of plotting deformation Vs load curve of a helical spring, one way will be starting from load zero and increasing till the spring achieves solid length. The other way will be loading the spring till solid length and measuring...
  12. A

    Magnetic field of cylinder with coils problem?

    Homework Statement In the picture in the figure, three coils are tightly wrapped around a non-magnetic cylinder of diameter Dcyl. Each coil is defined through the diameter of each wire comprising the coil, dcoil1-dcoil3, the current going through each coil, I1-I3, and the number of turns in...
  13. grandpa2390

    Calculating E/M for Helmholtz Coils -- help please

    edit: wait... I think the discrepancy is that I calculated Coulombs per kg? and the accepted value I was looking at was in abcoulombs per kg. If that is indeed the case, then my answer is indeed close to the accepted value of 1.76 * 10^11 Coulomb/kg. 1. Homework Statement I am trying to...
  14. E

    What is the value of the B field in Teslas, inside the Helmholz coils?

    Homework Statement For a current of 2.5 amps, what is the value of teh B field in Teslas, inside the Helmholz coils in the e/m apparatus? Homework Equations B = 7.7 x 10^4 x I , I is the current in amps. The Attempt at a Solution B = B = 7.7 x 10^4 x 2.5 amps = .001925 = 1.925 x 10^-3Did I...
  15. T

    MATLAB Mutual inductance of two disk coils (MATLAB)

    Hi, I'm been spending way too much time this weekend, wrestling with the equations provided in the paper [The mutual inductance of two thin coaxial disk coils in air, Babic S., DOI: 10.1109/TMAG.2004.824810], but I just can't seem to verify the results obtained in the examples in the journal...
  16. R

    Induction in two coils that are connected :S

    I'm a third year physics undergrad and I still massively struggle with electromagnetism - especially induction. Here's the opening part of the question: A loop is placed in an external alternating magnetic field that is perpendicular to the plane of the loop, with B=B0sin(ωt). Consider first...
  17. D

    Guitar Strings and Inductor Coils

    I need a little help with a project I'm working on. Here's the gist of it; I am taking two coils, hooking one into the input of an amplifier circuit and the other to the output. Both coils will be over an electric guitar string. The guitar string when vibrated will have a changing induction...
  18. S

    Regarding resistivity in heating coils

    I have a question regarding "ohm level" in a heating element in the design of a device designed to vaporize a liquid. I thought I had a pretty solid understanding of this but I've been told that I was wrong. So, I thought that if you increase the resistance (higher ohm) in a heating...
  19. P

    Multi-layer magnet with separate coils

    I am trying to make a very strong magnet that will only last for a short pulse, just a fraction of a second, with a high peak current. I am going to use 1mm (18awg) wire, so the resistance should be pretty low, but with even just 25m, it would be expected to have 0.5Ω. I would like to have...
  20. H

    Capacitance between adjacent coils?

    Hi everyone. I am trying to determine the capacitance between two adjacent coils. Each coil is identical, made of 20 awg wire consisting of 10 layers of 20 turns each, spaced about 1 inch apart and wound on a 1 1/2 inch diameter coil former. How would I go about finding/calculating...
  21. C

    Two Transformers, voltage before and after on two different coils

    Homework Statement We have a transformer with the primary coil carries 120 V and the secondary coil having 6 V. If you change the second coil to have 8V, what is the voltage in the primary coil? Homework Equations My textbook does not have any equations that involve just the voltage of...
  22. H

    Induction coils and contact materials

    Hi, I'm using an induction coil to heat up an electrically conductive material within the coil. However, I'm worried that adjacent electrically conductive materials, which are not within the coil will also have see a heating effect, due to induction not thermal transfer. I want to avoid this as...
  23. C

    What is the magnetic field of two parallel current loops?

    Homework Statement Helmholtz coils can be modeled as a pair of current loops oriented so that they are parallel to each other with a common axis in the x direction. The two loops have the same current I, and the same radius R, and their centres are at x = -d and x = +d, so the distance between...
  24. Newtons Apple

    Exploring the Significance of Coils in Electricity and Magnetism

    hey everyone, I have a questions, that is very general, and perhaps, silly... but why are coils so significant in terms of electricity and magnetic fields? why is it when you push a magnet through a coil, you get a charge, but not when you touch it to a straight copper pipe? Or when you see...
  25. T

    Tesla Coils Detecting Vacuum Leaks: Why?

    Why does Tesla coil detects vacuum leaks?
  26. B

    Kirchoff's voltage law with coils

    There is an idea that Kirchoff's voltage law could not be applied to circuit containing coils like this link. What makes me confused is that almost all books apply Kirchoff's voltage law to RL and RLC circuit.
  27. V

    Get Bifilar Wound Coils for Your Project: 2 of Each Type

    Hi anyone can help me to get these... i want bifilar wounded flat spiral and cylindrical coils for my project can anyone tell where i can get them i required in quantity of two each
  28. A

    Are My Calculations on Coils and Inductance Correct?

    Hi there I needed someone to check my answers for these questions and see if they are correct and if not if they can point me in the right direction the question is for revision purposes got an exam in a week. Thanks. A coil of inductance 4H and resistance of 80Ω is connected in parallel...
  29. N

    How to find the turns ratio between the primary and secondary coils.

    Homework Statement Find the turns ratio across the transformer such that a spark is given off at the points AB. The distance from point A to point B is 5.00 mm. AB is the distance across the secondary coil. The frequency and voltage of the primary coil is given. Homework Equations...
  30. K

    F=BIL Relationship with coils Explanation?

    Homework Statement There's no specific problem here so I'd say this template doesn't specifically apply. I'm doing a piece of coursework investigating F=BIL and electromagnets and I'm having some trouble. I think the issue here is the data that I've collected so bear with me. I've been making...
  31. U

    Mutual Inductance of coaxial coils

    Homework Statement Not sure if I'm correct or wrong..because usually M12 = M21 The Attempt at a Solution Here coil 1 and coil 2 are coaxial, with coil 2 being shorter and having smaller area.
  32. S

    Pulsing DC current through coils

    Hi, What hardware do I need to buy if I want to pulse DC power, say 12v through some regular coils with iron cores. Can I use a regular power supply connected to some other device? How would I pulse the output of the power supply?
  33. dennisk

    Separated paraLLEL COILS WITH MAGNETIC FLUX INTO ONE

    I have two parallel air coils attached to each other but separated by 3" of air. if I move a magnet past one coil it will induce a magnetic flux into it and that will create a voltage across it. Will that voltage transfer to the other coil thereby creating a magnetic pulse in the second coil...
  34. S

    Comparing Series & Parallel Connections of Helmholtz Coils

    Hi, With the condition that 2 helmholtz coils are parallel with each other sharing the same axis in space . . . What are the differences between electrically connecting up the coils in series and in parallel? cheers
  35. V

    Heating liquid using wire coils

    I'm trying to make ferrofluid according to this guide: http://www.sci-spot.com/Chemistry/liqimag.htm and in step 5 I need to heat the solution to near boiling but I don't have access to a bunsen burner or heating plate. Also I can't do this in the kitchen because this heating is to remove...
  36. W

    Mutual inductance of transformer with coils of different area and length

    Hello, I am trying to derive the mutual inductance between the two coils of a transformer. I want to do this for two coils with different lengths and different cross-sectional areas (assuming that one side of the transformer core is thicker than the other). The parameters are therefore: I1...
  37. T

    Generators and Coils vs Output Volts/Amps

    I know this is a bit of a newbie question but I want to learn something about generators. I want to build a simple hand cranked generator. Just a hobby. Making coils, and using magnets is the easy part but I don't understand the specifics around this. Can anyone tell me how to determine...
  38. A

    Electromagnetic induction between 2 coils problem.

    We know that 1)a change in current and voltage in a coil may result in induction in other stationary coil..this induction is directly related to frequency..ie The higher the frequency the more intense the induction effect. 2)we also know that there is no induction in case of DC current flow...
  39. K

    Electromagnetic induction with two coils and an iron heart

    Homework Statement Two coils are place on an iron heart, like in the picture. The top Coil is connected to a galvanometer, the second could be connected to a power source. Homework Equations Will an electric current flow through the top coil when: a) connecting and then...
  40. P

    What are the Induced Poles in Coaxial Coils Facing a Moving Bar Magnet?

    Homework Statement A bar magnet is moved between 2 coaxial coils A and B as shown in the figure.The end planes of the two coaxial coils facing the magnet due to induction will behave? Homework Equations The Attempt at a Solution My solution: It will induce south pole in A and B...
  41. R

    Calculate Equivalent Inductance of Coils Connected in Series

    Homework Statement There are two coils wined around the same closed iron core. Their inductances on this iron core are measured to be 4 henry, and 9 henry. Then the two coils are connected in series. What will the equivalent inductance be? Homework Equations ... The Attempt at a...
  42. H

    Earth's Magnetic Field Experiment / Helmholtz Coils?

    Homework Statement In my ab, we were supposed to obtain the horizontal component of the Earth's magnetic field by measuring the period of oscillation of a bar magnet in a known field using the Helmholtz coils, a resistor, and an AC power amplifier. Now during this experiment I had issues with...
  43. E

    Understanding Coils and EMP Bombs: Deciphering 5T 5B Turns

    I'm reading a site about an EMP 'bomb' and they list the number of turns as "5T 5B" does anyone know what that means? is it something simple like 5 top and 5 bottom? here's a link for the site if any is interested. thanks.
  44. T

    Explosive ejection of higher frequencies by lower freq In 2 tesla coils

    Greetings PF'rs I'm researching a phenominon called ball lightning and one supposed method of generating ball lightning is to take two tesla coils of different resonant frequencies but are pulsed with the same secondary coil. The lower frequency coil induces a current in the nearby higher...
  45. R

    Can the EM Spectrum Be Converted to Electricity Using Transformer Coils?

    The EM field of a magnet or electromagnet can be converted to electricity with the use of a transformer (coil). My question is... Does that hold up for the whole EM spectrum... IR through Gamma?
  46. E

    Heat Transfer Rate of 2 Heating Coils on Aluminium Plate

    Homework Statement ==================== <---- aluminium plate ⁣⁣⁣⁣⁣⁢⁢⁢⁠⁡⁡⁢⁢⁢...O .....O... <---- heat coil(O) Given an aluminium plate put on 2 heating coil(O), assuming no heat loss, how much is the heat transfer rate from the coil to the plate? Put the power of each coil as W...
  47. F

    How do two layer voice coils work?

    I understand how single layer/wound voice coils work, where the positive lead is at one end of the coil and the negative is at the other, but how do double wound coils work where both leads terminate at the top? See photos below for what I mean by double and single wound. On the double wound...
  48. D

    B Field Confinement for Toroidal Coils Driven by AC Current

    It is said that toroidal inductors/coils (see http://fa.tu-sofia.bg/te/Brandisky/images/toroidal_coil.jpg ) that are perfectly axially symmetric will completely confine B fields. That is, the B field inside will be nonzero and will circle the toroid, but the B field outside the toroid will be...
  49. C

    Calculating Magnetic Field Between Coaxial Circular Coils

    Homework Statement Two coaxial circular coils of radius R = 15 cm, each carrying 4.0 A in the same direction, are positioned a distance d = 20 cm apart, as shown in the figure. Calculate the magnitude of the magnetic field halfway between the coils along the line connecting their centers. (μ0 =...
  50. S

    A quick question regarding three phase coils connections of a motor

    Hello everyone: I have a quick question regarding connecting a three phase power supply to the coils of a three phase motor. Now I know that if you had 3 pole pairs, 6 coils 120 degrees apart around a stator, that each diagonally adjacient coil gets connected in series and each of these...
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