What is Spark: Definition and 110 Discussions

A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture by an electric spark, while containing combustion pressure within the engine. A spark plug has a metal threaded shell, electrically isolated from a central electrode by a ceramic insulator. The central electrode, which may contain a resistor, is connected by a heavily insulated wire to the output terminal of an ignition coil or magneto. The spark plug's metal shell is screwed into the engine's cylinder head and thus electrically grounded. The central electrode protrudes through the porcelain insulator into the combustion chamber, forming one or more spark gaps between the inner end of the central electrode and usually one or more protuberances or structures attached to the inner end of the threaded shell and designated the side, earth, or ground electrode(s).
Spark plugs may also be used for other purposes; in Saab Direct Ignition when they are not firing, spark plugs are used to measure ionization in the cylinders – this ionic current measurement is used to replace the ordinary cam phase sensor, knock sensor and misfire measurement function. Spark plugs may also be used in other applications such as furnaces wherein a combustible fuel/air mixture must be ignited. In this case, they are sometimes referred to as flame igniters.

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  1. Borek

    Power surge video - why does the spark travel?

    Any idea what is the physics behind? Why does the spark travel down the line?
  2. ZdMh

    Electric spark between person and another person/thing

    Hello All! You know sometimes you touch another person and you felt an electric spark between both of you, or sometimes with things like the door handle, etc. I moved lately to a hot and dry country where the temperature is around 40-45 Celcius degrees now in August, but since I moved here this...
  3. L

    Engineering Would the two stroke spark ignition PV digram be same as for a 4 stroke?

    Would two stroke spark ignition PV digram be same as 4 stroke spark ignition. both have otto pv diagrams.
  4. F

    Question about a simple model for for back EMF

    Summary:: I've found an exercise about sparks caused by back emf. The exercise is based on a mathematical model of the current flowing in the circuit around the time when the switch is closed. I'm wondering to what extend that model is realistic The exercise I'm referring to proposes this...
  5. M

    Modeling a spark gap--How to solve a DE with a step function

    Honestly not sure how to go about this. Again this is one equation of 4 that I have. I considered using Laplace transforms but taking the Laplace transform of a step function whose argument is one of the variables being solved for doesn't seem possible. Also, if there is an alternative way to...
  6. Zaya Bell

    B Is a Spark Necessary for the Production of EM Waves in the Hertz Experiment?

    Hello, so I was reading bout the Hertz experiment in different text and they always say something about the Spark causing accelerated electric charge. So I was wondering, is the spark necessarily for the production of EM waves? If yes, why? Because as I recall, applying an ac voltage should...
  7. Charlie Cheap

    Automotive Spark length of a points ignition compared to an HEI system

    Having made/modified my own distributors for years, I was surprised to see MSD (Multiple Spark Discharge) company show their graph using Points, HEI, and Performance HEI comparisons, with little difference in Horse Power made, up to about 6000 RPM. I know a points mechanical system makes a...
  8. jerromyjon

    High voltage coil discharge polarity for vehicle spark plugs

    I've recently had a discussion with fellow technicians in the automotive industry about spark plugs and some systems having "opposite polarity" on the ignition coils. (specifically the secondary coil which sends the high voltage pulse to the plug which sparks the fuel) Common sense tells me...
  9. Alex Karatzky

    How to optimize spark gap Tesla coils

    My elementary school had its first annual science fair a few weeks ago, so me and my friend signed up and we decided to do it on wireless electricity. So naturally, we built a tesla coil. It took a couple of tries, but we eventually got it to barely illuminate a portion of a fluorescent light...
  10. Alex Karatzky

    How to optimize spark gap Tesla coils?

    My elementary school had its first annual science fair a few weeks ago, so me and my friend signed up and we decided to do it on wireless electricity. So naturally, we built a tesla coil. It took a couple of tries, but we eventually got it to barely illuminate a portion of a fluorescent light...
  11. F

    Automotive What Causes Spark Plugs to Spark?

    What makes the spark plugs in an automobile engine or any other type of gasoline engine spark?
  12. H

    Spark generation in capacitors

    If we directly connect the two plates of an ideal charged parallel-plate capacitor, a spark will generate. What is the exact reason of spark?
  13. A

    Breakdown voltage of humid air in uniform electric field

    Could anyone please let me know if breakthrough spark can happen, or, in general, what will happen in the below system? Note 1: the dielectric layers have a much higher breakthrough voltage than humid air. Note 2: the intensity of the electric field that develops in the flow of the humid air is...
  14. rodv92

    Decreasing gas breakdown distance in a spark gap with UV

    Hello ! I am currently investigating a technique that would allow several spark gaps to breakdown synchronously in an enclosed but not hermetical cavity, flushed with N2 at 1atm and ~25°C My idea was to use "indirect" photoionization (basically a synthetic fused quartz UV flash discharge inside...
  15. N

    I Mysterious Flashes of Light in Dark Room

    I saw strange flashes of light last night in a dark room and am wondering what caused them. They seemed the only happen when I moved the comforter, but it was not always in the same area. I thought at first it was a brief reflection of light, but I couldn't find a source for the reflection that...
  16. HyperTechno

    Does using dual spark plugs per cylinder make any difference?

    There is this bike manufactured in India with a 180CC single cylinder petrol engine with Twin Spark plugs. They highly market their "twin spark technology". Well according to my knowledge, I don't think that will make much difference in performance and efficiency. What do you think? Is this just...
  17. I

    I Leyden Jars increase spark length?

    Good Evening/Morning/Afternoon Everyone, Question: Why is it that demonstrations of Van de Graff generators use Leyden Jars in series to get bigger sparks? If a spark gap's size determined by voltage, and Leyden jars are simply to be treated as capacitors which wouldn't increase voltage, why...
  18. mfig

    How can I design a spark ignition system with a wider energy delivery range?

    Hello, I would like to design a spark ignition system with a wider range of energy delivery than a typical MSD system. On the MSD systems I have looked at, they are limited to about a 10 mJ range, but I need to go from, say 5 mJ to 1 J if possible. Does anyone know of a packaged system like...
  19. I

    Understanding Spark in Relay Contacts: Causes and Solutions

    Why is there a spark in the relay contacts? Suppose that the coil and the contacts are connected to two different power supplies. If i suddenly disconnect the power supply to the coil, then the voltage across the coil will increase and a spark will jump across the switch that I used to...
  20. J

    Energy lost from sphere due to spark

    1. Homework Statement Homework EquationsThe Attempt at a Solution I did this : 1/2 (2.7x10^-6)(150x10^3) - 1/2 (1.575x 10^-6)(75x10^3) =0.143 J But the answer is 0.15 , where did I did wrong?
  21. yi ru huang

    Spark gap switch and 2N6798 in PSPICE

    Error is like " no PSPICE template for 2N6798 ， spark gap switch how to find the .ilb of spark gap switch and 2N6798? thank for your help.
  22. T

    How many volts is required for a tiny spark to be created?

    Homework Statement How many volts is required for a tiny spark to be created in electrostatics? Homework Equations No equations The Attempt at a Solution 5,000 watts
  23. R

    What is the Spark From an Oil Burner Igniter Coil?

    When I take a step-up transformer say from the igniter coil from an oil burner and step up the voltage from 110 volts to 10,000 volts with just a very small fraction of an amp in the secondary why is it I get a huge spark. Is the spark not a large collection of electrons jumping the gap because...
  24. A

    Can some bright spark help me? Colour of Light vs Time

    I'm writing a Science Fiction story which has one place where time runs at normal speed, and another place next to it, where time runs at a much slower speed. If you stand in the normal place and look into the slow place, you will see people moving around as if in slow motion. But what would...
  25. cnh1995

    Spark Gap Transmitter: EM Wave Generation & Transmission

    I recently read about the early spark gap transmitter..But I don't understand how the EM waves are generated and transmitted..Induction coil creates sparks in the gap but what produces the waves and how are they transmitted?? Need I study electromagnetic waves in detail??
  26. H

    Intake manifold pressure and spark timing

    Why does higher intake manifold pressure results in increase in the degree of spark advancement? Similarly, why is the torque higher for higher intake manifold pressure?
  27. S

    Dual spark plugs, firing between them?

    Would it be beneficial at all (as regards lean burn and rate of flame propagation) to have two spark plugs, one charged with a high positive voltage, one charged with a high negative voltage, such that the spark jumps between the two plugs? My thinking (which is probably wrong, as it often...
  28. L

    Spark with connecting power supply to board

    When I connect a DC power supply to a board, why do I get a spark. I connect the ground terminal first and then the Vcc terminal(24V). When I connect Vcc with an alligator clip, I get a spark. Is it because of charging of the bulk storage capacitor?
  29. O

    Understanding Corona, Arc, and Spark in Fluids: Explained

    There are tons of different explanation for each of them in internet. Could someone please confrim the explanation below which I gathered from different places; If the electrical field in a fluid reaches the fluids dielectrical strenght, dielectric collapses and corona happens, but since the...
  30. T

    Why do capacitors create a spark when shorted?

    Why exactly is it that a spark is created when capacitors are shorted? Even with a few volts capacitors will spark when shorted, with my limited somewhat basic knowledge this has puzzled me. Any help is greatly appreciated.
  31. R

    Why does the Van der Graaf Generator produce a spark?

    Where the electrons come from? Do they leave the sphere or the object? Or maybe even the rubber band inside the generator? I'm having a hard time figuring this out. Also, how does this prove the charge of the sphere?
  32. C

    Charge on point charge to create a spark

    Homework Statement Suppose a free electron in air is 1.1cm away from a point charge. What minimum charge must this point charge have to cause a breakdown of the air and create a spark? I already have the Electric field and force, which I solved to be E=7.2x10^6 N/C F=1.2x10^-12 N...
  33. D

    12V battery to create spark gap?

    Hey okay, so I have a 12V source which can provide a max of 10 mA, and I also have a switch that can go from open to close in 1 ms, How can I create an inductive circuit that will create a spark gap between electrodes that are 3mm apart? I did the math and found the breakdown voltage to be...
  34. B

    Can electrical motor produce a spark?

    Hi Guys, I am building an equipment to Zone 2 explosive atmosphere. Machine will be powered by the pneumatic motor. I just had an argument with my boss. He says that I need to order an atex approved motor and I say that I don't because the motor will never produce any spark. What are your...
  35. G

    What causes a spark (Eletricity)

    Hi all, I am currently reading a book that tries to compare Hertz transmission and reception of radio waves with the photoelectric effect. (I am aware that Hertz discovered the photoelectric effect and what it is although not why it occurs). The book states that; the magnitude of sparks...
  36. F

    Investigating Ignition Sparks in Cars with Waste Spark Management

    hi i have come across a post regarding ignition spark in cars with waste spark management. and my question is... that spark that comes out of that coil or any tesla coil what does it have?is it positive or is it negative or is it something else... i have come across something that i can not...
  37. joe_cool2

    Electric field necessary to create a spark.

    Homework Statement a) The average distance an electron travels between collisions is 2.0\mum. What acceleration must an electron have to gain 2.0 x 10-18 J of kinectic energy in this distance? b) What force must act on an electron to give it the acceleration found in part a? c) What strength...
  38. E

    Can a spark form through vacuum?

    Hey guys, I was looking online at sparks and how they form, and the amount of energy needed to form them when this question came up to my mind. can a spark form through vacuum? or it actually needs particles to go through them? and if it can form...what is the value of the breakthrough for...
  39. C

    Producing a Spark Reliably with a Circuit

    I'm playing around with a circuit, I want to produce a spark reliably. If I take two wires and just barely touch them, then discharge a capacitor across the junction I get a nice spark. However this only happens once, maybe twice before the metals seem to fuse together at which point I cannot...
  40. H

    Trying to Build a Spark Getter

    Hello, Recently I have been trying to build a spark getter. The idea is that a high voltage is applied to a capacitor consisting two titanium plates, once the breakdown voltage is reached, a spark is caused, and small particles of titanium (our getter) come off the anode and the cathode. I...
  41. A

    Speed of electric spark, arc and conductive ionized gas

    Dear colleagues, If an arc or a spark traveling in vacuum is actually the electrons jumping across vacuum, do they travel at near light speed? From another point of view, devices like thyratrons use ionized gas molecules to conduct electricity, at what speed are those ionized molecules...
  42. C

    How can I use a MOSFET and voltage multiplier to generate a high voltage spark?

    I need to make a large voltage, possibly to make a spark across a 0.05mm gap or at least to make a very large voltage across a resistor. I need this to be triggered digitally by a micro-controller. I was thinking of setting up an inductor and a power MOSFET, but I don't know if this will...
  43. F

    E field distribution in spark discharge

    Hi, I just joined this forums. I'm currently doing my master thesis in mechanical engineering, however, my topic is related to plasma physics. As part of my results, I need to simulate an audio frequency electric discharge in a spark plug in air, in Ansys HFSS software. The discharge is...
  44. P

    Spark plug/Igniter/Spark gap in PSpice

    As far as I can tell, none of these come with the student edition of PSpice. The first problem is I can't find a model for any of these things. The second problem is I don't know how to import a custom part. Worst come to worst, I could make the part myself, but once again, I have no experience...
  45. D

    Perfecting a spark gap switch - help needed

    Hi everyone , this is my first post here :) . I am an auto electrician , my hobby is photography. I am interested in high speed photography and have invented a new form of photography in a way . I call it 'superspeed photography' . It involves taking a picture of something that is triggered by...
  46. Z

    What is the process called when metal is heated in a microwave oven?

    Recently I came across with one video in youtube where the guy in the video did experiment on microwave oven. He heat up aluminium foil in the oven and after a few second, the foil started to produce spark. This is my first time watching something like that. I never knew that when metal is heat...
  47. F

    Mutual inductance in a spark plug

    Homework Statement The ignition coil supplies V=20kV to the spark plugs. The maximum current in primary coil Imax=4.0A. The current is interrupted 100 times/sec by the distributor points. Estimate the mutual inductance M of the primary and secondary coils. Hint: I have to make a...
  48. O

    Why metals spark in microwave ovens?

    Hi, sorry for the childish title. But this problem is supposed to be solved quantitatively using Laplace's equation, so it's not so straightforward. Homework Statement (a) Explain why it is possible to keep a teaspoon in a cup of water heated in a microwave oven without spark formation, but...
  49. P

    Ignition Coil Won't Spark from Mosfet but DOES spark By Hand? HELP?

    Ignition Coil Won't Spark from Mosfet but DOES spark By Hand? HELP!? I'm trying to get an ignition coil to create sparks running it with a Mosfet powered by a 555 timer. The Mosfet is definitely switching. I checked it with resistor, ampmeter, and o-scope. Everything is behaving predictably...
  50. C

    Automotive Closed loop spark advance and it's effect on abnormal combustion.

    Recently I read about Saab's experiments at closed loop spark advance, and it got me wondering. If you are controlling spark advance to maintain a constant peak pressure position of 20 deg after TDC is it possible to get into a situation where detonation or pre-ignition is possible. It seems to...
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