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. C

    Bit of confusion with coils and electromagnetic induction

    Apparently for emf to be induced in a coil, the magnetic field (or part of it) has to act along the normal to the coil face. So does this mean that the coil moves side-ways through the magnetic field? where instead of moving through its length (its longer side), it moves through the coil face...
  2. R

    What type of software to configure coils, inductors, transformers?

    What type of software? Hello everyone, I'm looking for a simple software program that I may be able to configure coils, inductors, transformers, core selection etc. Basic ic availability, selection of switches, LEDs, types/strenghths/shapes of permanent magnets. I'm aware that there is a lot...
  3. O

    Coaxial coils in dielectric material

    Hi everyone I have a problem to solve, I already simulated it with FEMM, but I wonder if it is possible to find an analytical solution. Let's say that there's a small coil (100 turns) around a pipe (2in diameter), the pipe is filled with air. This pipe is located inside a bigger pipe...
  4. A

    Coils, Current & EMF: Exploring the Interaction

    I guess it does not produce any field in 2nd coil because there's no change in current in coil right?So there won't be any emf .. but coil 2 has magnetic field passing through it which results in current in coil(by forcing movement of electrons of coil 2 SINCE ELECTRONS ARE ALREADY IN MOTION...
  5. T

    Calculating Magnetic Fields in Solenoids vs. Current Loops and Coils

    Homework Statement There is a solenoid, with field B at its center, radius r, length L and maximum current I. Calculate the minimum number of turns the solenoid must have.Homework Equations Ampere's Law: (closed)∫B\cdotdl=\muI n=N/L Biot-Savart: B=\muIN/(2\pirThe Attempt at a Solution Solving...
  6. X

    Why aren't the coils in electric motors insulated?

    In all the electric motors I have taken apart, the coils on the armature have never been insulated. This has always confused me because, how could the coil make a sufficient magnetic field if it shorts out to the adjacent wires from lack of insulation?
  7. Y

    Exploring the EMF of Guitar Pickup Coils

    I have a discussion on how guitar pickup work, pickup is a coil with thousands of turns and magnet poles in the middle of the coil under each strings. My idea is the magnet poles magnetize a short portion of the string and when the string vibrates, it create a varying magnetic field. When the...
  8. K

    How to make inductor coils?

    I am looking forward to a small project. For this i need some inductor coils. I searched through the local shops, but i could find any inductor coil. According to what i know inductor coils are made by making loops using wires. http://www.instructables.com/id/Making-a-Simple-Induction-Coil/ Is...
  9. B

    Please explain - total electic field Ec + En within the coils must be zero

    Please explain -- total electic field Ec + En within the coils must be zero Hi This is from the text University Physics. In pg. 1035, chap 10, in order to justify the use of Kirchoff's rule to analyze circuits containing inductors it is written : Let's assume we are dealing with an inductor...
  10. M

    Motion of wire in B field -vs- motion of electrons in helmholtz coils

    Hi guys, This may be a daft question (or set of questions), but I just want to bounce a few ideas off the wall once I understand some simple issues. Can anyone tell me why if you pass a current through a wire in a magnetic field, the wire will move perpendicular to the both the current...
  11. R

    Magnetic Field at the midpoint between two current carrying coils

    Homework Statement Two identical coils are parallel to each other on the same axis. They are separated by a distance equal to their radius R. They each have N turns and carry equal currents I in the same direction. Find an expression for the magnetic field strength at the midpoint...
  12. J

    Solenoid, calculate number of coils

    Homework Statement We want to construct a solenoid with a resistance of 4.30 Ω and generate a magnetic field of 3.70 × 10−2 T at its center when applying 4.60 A of electrical current. We want to use copper wire with a diameter of 0.500 mm. If we need the solenoid's radius to be 1.00 cm...
  13. Femme_physics

    Industrial electronics. Question with coils and diode.

    Homework Statement http://img198.imageshack.us/img198/1421/vintm.jpg Given that k = 2 A) Draw in a qualitative manner the following letters Vin, VP, Vs, Uxy, UR1, UR2, UD B) Calculate the power in R2 C) Calculate the average current through R1 The Attempt at a SolutionI'll start with a...
  14. E

    Tesla coils / Toroidal inductor flux

    I've been reading up on tesla's wireless power transmission lately, and I've been wondering how magnetic flux through the center of a toroid induces a voltage in its coils. From what I understand, the time derivative of magnetic flux through a loop is proportional to the induced voltage...
  15. O

    How does the configuration of two coils affect voltage readings in a circuit?

    Homework Statement given two coils one with N1 rings legnth L1 the other N2 L2, one inside the other the radius is not given.. N1 is connected to battery V1 and N2 is connected to volt-meter what will show the volt-meter? (use N1,L1,N2,L2.V1) Homework Equations Faraday's law of induction[...
  16. C

    Pulses, cables and toroidal coils

    Hello. I just came to imagine a "thing" that I'm not able to understand correctly, so maybe you can help me. Imagine a high voltage source, and a circuit made of cable capable of handle high currents (with low resistivity) and a load with medium to high resistance (say 10 KOhm) Now you...
  17. M

    What happens when a switch is closed in a circuit with two coils?

    Homework Statement when the switch is closed , describe what will happen to the meter reading, the direction of the current flow, if any, and the magnetic fields produced in the two coils Homework Equations none The Attempt at a Solution the current flow is shown in the pic...
  18. P

    1 wire power transmission using coils.

    Hello Physicists, I am doing my final year of High School in Australia and our current topic is magnetism and related fields. Physics is my favorite subject after maths and I tend to query a lot of things. Here is my basic Idea: My basic instinct tells me that the orange wire must be...
  19. M

    Solving Helmholtz Coils: Diagram, Magnetic Field & Current

    Hi I'm suppose to find the direction of the magnetic field and the current in the diagram below and I was just wondering if I did this correctly. (red is magnetic field and blue is the current) Diagram: http://i324.photobucket.com/albums/k327/ProtoGirlEXE/100_0702.jpg And I have a few...
  20. W

    Compress air vessel has a volume of 10 ft3 .Cooling coils holds

    Homework Statement Compress air vessel has a volume of 10 ft3 .Cooling coils holds its temperature at 68F. The pressure now in the vessel is 100 psi. Air is flowing in at the rate of 10 lbm/hr.How fast is the pressure increasing? The Attempt at a Solution What I have done is...
  21. F

    Building a Pair of Helmholtz Coils - Questions & Tips

    Hi, I'm building a pair of helmholtz coils to do a variety of magnetism-related experiments. I've borrowed an old Avo Douglas coil winder and plan to do a couple of thousand turns on two sections of 50mm or 60mm diameter pipe. Some nylon threaded rod will pass through the middle of each coil...
  22. T

    What happens when Connecting step-up and step-down secondary Transformer coils?

    This website is a great idea. (I'm a thread vergin) Not sure if its standard but where I live 'step up' is secondary = higher voltage Opposite for 'step down'. What would the result be if you connected one secondary with a high voltage and low current in series with a secondary that had a...
  23. M

    Mutual Inductance for a Pair of Coils

    Homework Statement http://nplq1.phyast.pitt.edu/res/csm/csmphyslib/type66_inductance/PairOfCoils.jpg Coil A is a large 400 turn circular coil of radius 91.0 cm. Circular coil B has 160 turns, a radius of 2.0 cm and is located L = 92.0 cm from coil A along the same axis. The planes of the two...
  24. 1

    Flux Linkage through two coils

    1. Coil 1 has an inductance of 4.50×10-2 H and 140 turns. Coil 2 has an inductance of 8.00×10^-2 H and 230 turns. The coils are rigidly positioned with respect to each other, their mutual inductance is 5.00×10^-3 H. A 7.00×10^-3 A current in coil 1 is changing at a rate of 7.0 A/s. What flux...
  25. K

    Scanning Electron Microscope Scanning Coils Kapton

    Hello, I am working on researching new ways to insulate some scanning coils on the SEM I work on. Currently we use Kapton to insulate the wires but it becomes brittle and wears over time easily. I am looking for alternatives to using Kapton for the scanning coils. Any ideas and suggestions...
  26. B

    Compute Joule Heat in Heating Coils

    Homework Statement Two heating coils have resistances 12.0 ohms and 6.0 ohms, respectively. a)What is the Joule heat generated in each if they are connected in parallel to a source of emf of 115V? b) What if they are connected in series.Homework Equations Am I doing this question properly? The...
  27. M

    Designing a Racking System for Sheet Metal Coils

    Hi, ***I just noticed this that I posted this in the wrong section thinking I was in the engineering forum...sorry!*** I'm designing a racking system to store sheet metal coils (see attached sketch). I calculated the I and S values required and according to my calculations, 4 x 4 x 3/8...
  28. M

    Force from a magnet passing through coils

    Hi there I'm engineering a suspension system with the damper consisting of a magnet going through some coils. As the energy produced from this is proportional to the velocity of the magnet, this would be ideal for an "energetic" damper. To calculate the damping coefficient produced, I...
  29. X

    Find B Field of Helmholtz Coils

    Homework Statement We have 2 circular loops, each of radius R with current I in same direction. This is called a Helmholtz coil. The loop axes are along the z axis and the centers are at z=+/-s/2. Find the magnetic field along the z axis between the 2 loops. Homework Equations...
  30. J

    Inductance Variations in Air-Cored Coils: Why the Numbers Don't Always Match

    Why the values of inductance for an air-cored coil are not exactly the same for changing current across it in practice??
  31. G

    Helmholtz Coils and Iron Cores

    Hi, I'm doing a project that involves the use of Helmholtz coils. We have coils and can calculate the magnetic field produced using the standard equation and taking everything into consideration. I know we can boost the magnetic field strength of the coils by introducing and iron...
  32. T

    Coils rotating in a magnetic field find maximum emf and magnetic feild strength

    Homework Statement coils rotating in a magnetic field are often used to measure unknown magnetic fields. As an example, consider a coil of diameter 2.00 cm with 72.0 turns that is rotated about an axis perpendicular to the field at a rate of 20.0 Hz. If the maximum induced emf in the coil is...
  33. E

    Learn How to Connect 2 Coils for Your Multistage Coil Gun

    I have a multistage coil gun. and i was wondering how exactly do u connect the coils together. lol i thought u take wire from the first coil and use that to start the second coil.
  34. S

    Stator ring coils model in Multisim or Orcad

    Hello everyone I am trying to simulate a three phase AC powered six coil stator ring using Multisim or Orcad. How would I do this? Would I use regular inductors as the coils or would I use coils with iron and steel rods inside them? Would I just connect each inductor coil pole pair...
  35. J

    High Impedance Air-Core Coils: Where to Buy?

    Hello All, I have been doing some experiments with inductors of various sizes and inductances. I was wondering if anyone here knows of any suppliers out there that sell high impedance air-core inductors (a few thousand turns of high gauge wire (30 gauge or so)) that can be purchased off the...
  36. 7

    Do Both Magnets Induce Current in the Coils When Moved Towards Them?

    I've already done an experiment to show that if I take two coils and connect the leads together I can physically move one magnet towards the first coil and it will draw a second magnet towards the second coil. Of course this depends on how you wire the coils together as it can also repel the...
  37. S

    Stator ring connection and coils question

    Hello everyone: I am trying to find a program or formula that will help me figure out how many windings, turns of coil, are needed per coil on a 6 coil steel stator ring powered by 3-phase AC power to get a certain magnetic field strength, about 1.3T. Is there any way that you could help me...
  38. V

    Solving Task with 0.25 Induction and 75 Coils: Tips & Formulas

    I have problems solweing this task. In magnetic field with induction 0.25 is a flat coil which has N=75 whrols with a radius of 25cm. Angle between Coil‘s flat and magnetic force lines is 60 degrees. How much torque afects coil in a magnetic field, while there flows 8A of curent? What work...
  39. B

    Inductive interference from two EM coils (aka a transformer)

    I've been wondering about this for a long time. The little black box that you plug into the wall so you can power your electronic devices contains a general run-of-the-mill transformer. But if the power is completely shut off to the device: not draining any current waiting for a power button...
  40. H

    Quench spreading on multiple coils superconducting magnet

    The multiple coils superconducting maget is uaually quench protected by bypass diodes. The heat spreading model is mentioned on textbook for coil to coil quench spreading. But the heat spreading is not fast enough for magnet quench protection. Because the theoretical quench protection...
  41. F

    How Is Current Induced in a Coil by a Changing Magnetic Field?

    Homework Statement A strong electromagnet produces a uniform magnetic field of 1.60 T over a cross-sectional area of 0.200 m2. We place a coil having 190 turns and a total resistance of 21.0 around the electromagnet. We then smoothly reduce the current in the electromagnet until it reaches...
  42. P

    Light waves represented by coils

    Thanks it makes a lot more sense now!
  43. N

    Understanding Two Coils - V1/V2 & I1/I2 Ratios

    http://i47.tinypic.com/k0n0gi.jpg i know that V1/V2=1/a I1/I2=-a how they interpret the left resistor to be like this ?
  44. B

    Relation between RPM, coils and kW-output in electrical generator

    Hi, new to the forum here I have this bike-engine here and I am thinking whether it would be possible to mount it to an electrical generator. The thing is it easily hits RPM's up to 13000. My question is if I make a magnet spinning at let's say 10k rpm what poweroutput are we talking then...
  45. J

    Unused Alphabet Letters & Irregular Distance in Loading Coils

    Why not all letters of the alphabet are used in loading coil distance? and why there is no pattern followed in the spacing designation?thank you very much...
  46. M

    Making Self resonating coils for wireless electricity transfer How to do

    Making Self resonating coils for wireless electricity transfer ! How to do @@ Dear Friends , I would like to make the wireless electricity project as done by MIT team.i am bit confused about how to make the two different coils resonate at the same frequency ?? Please help me... Thanks...
  47. N

    Investigating Induced Current in Circular Coils

    If I have a top view of two circular coils of conducting wire lying on a flat surface, what is the direciton of induced current that appears in the smaller coil when the switch in the larger coil is closed? I'm trying to figure out: 1.) which direction the induced current would flow through...
  48. O

    Coils of wire with current in a magnetic field

    Homework Statement The figure shows a wooden cylinder with mass m = 0.100 kg and length L = 0.800 m, with N = 20.0 turns of wire wrapped around it longitudinally, so that the plane of the wire coil contains the long central axis of the cylinder. The cylinder is released on a plane inclined at...
  49. J

    Mutual Inductance (Two coils connected in parallel to source)

    Hi, I recently performed a stator core loop test and am now in the process of capturing the setup and results in a report. A short explanation of the test setup and execution: A cable is wrapped around the core and energized, which induces a magnetic flux through the core. The core...
  50. C

    Mutual Inductance of two coils

    Homework Statement The mutual inductance between two coils is 0.0100 H. The current in the first coil changes uniformly from 2.7 A to 5.0 A in 0.160 s. If the second coil has a resistance of 0.600 Ω, what is the magnitude of the induced current in the second coil? Please show stepsHomework...
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