What is Smoke: Definition and 100 Discussions

Smoke is a collection of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires (including stoves, candles, internal combustion engines, oil lamps, and fireplaces), but may also be used for pest control (fumigation), communication (smoke signals), defensive and offensive capabilities in the military (smoke screen), cooking, or smoking (tobacco, cannabis, etc.). It is used in rituals where incense, sage, or resin is burned to produce a smell for spiritual or magical purposes. It can also be a flavoring agent and preservative.

Smoke inhalation is the primary cause of death in victims of indoor fires. The smoke kills by a combination of thermal damage, poisoning and pulmonary irritation caused by carbon monoxide, hydrogen cyanide and other combustion products.
Smoke is an aerosol (or mist) of solid particles and liquid droplets that are close to the ideal range of sizes for Mie scattering of visible light.

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  1. ruxy667

    Automotive What does the smoke color means in diesel car and petrol car?

    Hi there, i just started to learn mechanic about few years ago and I wanted to know about car smoke color, What does the smoke color means in disel car and petrol car, Black,Blue,Grey,White smoke color?
  2. jtbell

    How Far Can Smoke From Canadian Wildfires Travel?

    Four views of Manhattan from New Jersey, at about 10 AM, noon, 1 PM and 2 PM today.
  3. H

    Smoke Alarms and radiation from them

    Why are smoke detectors with Americium exempt from leak testing when there are ones in older houses maybe 30 years old and one needs to open them up to change the battery. Surely the Americium could leak out over time from the ionisation chamber?
  4. S

    Radiation Safety: Understanding Exposure and Risk

    Recently when cleaning, I opened the cover of our ionisation smoke detector and as I was touching all around the inside of the smoke detector with my bare hands and most importantly including all the sides of the ionization chamber with the radiation symbol on it which contains the radiation...
  5. weirdoguy

    Velocity of wind based on the shape of a smoke trail

    Hi everyone. My high-school student got the following homework exercise at school which I have problem with: Smoke from the steam locomotive is carried by horizontally blowing wind. Shape of the smoke trail is shown in the attached figure. Using the drawing, determine velocity of the wind...
  6. jaumzaum

    I Why Does Smoke Rise? An Exploration of Physics Principles

    If we consider that the heating of the products created in the combustion of paper to be an almost adiabatic process (as it's extremely fast), then $$T^{1.4} P^{-0.4} = const. $$ If we double the temperature, we multiply the pressure by 11.3 The density of an ideal gas is $$ \rho=PM/RT$$ If we...
  7. Spinnor

    Smoke, smoke, smoke that cigarette

    Reading the Forum insights article, https://www.physicsforums.com/threads/i-know-the-math-says-so-but-is-it-really-true.994400/ I read something interesting, from post #19, " For example, about two months ago I read on a Russian news website that two independent groups from French universities...
  8. M

    Optical Laser to refract/reflect water vapor and smoke.... angles?

    Building visibiity sensor... What is best angle to detect water vapor reflection from laser, and refraction? I plan to have two open cylindrical containers painted flat black and put inside each other so the overlap is about 0.5-1" (adj to limit ambient light vs airflow). Laser is cheap red...
  9. F

    Mounting fire / smoke alarms with magnets

    I am building a detachable smoke detector that I'm planning to install with magnets. I am concerned about the safety using this method, because of my knowledge of how magnets react to / affect heat and smoke. I wouldn't risk having the alarm detach itself during a fire, or the magnet to...
  10. S

    How could smoke alarm beep without battery and disconnected?

    It beeped when I had removed battery and disconnected it from ceiling. The power has to come fromm somewhere, so how could it beep?
  11. N

    Electrostatics from particle laden air

    Is it possible to generate static electricity from air flow containing particles example smoke or dust flow, or does anyone know of experiments such as the kelvin water dropper converted to generate static from air flow ? Thanks
  12. jim mcnamara

    Smoke plume map of California fires

    https://www.cnn.com/2018/08/10/us/smoke-california-wildfire-reaches-nyc-wxc-trnd/index.html Reaches completely across the continent.
  13. V

    Touched a smoke detector and then put hands in mouth?

    Hi. I have a very embarrassing question to ask. I was changed the battery in my smoke detector, which is the sort that uses americium to work. I have a bad habit of chewing and swallowing my nails, and also picking and my nose and swallowing the stuff from my nose, too. I'm paranoid that I...
  14. f95toli

    Why do e.g. smoke detectors need specific battery models?

    I have once again come across a smoke detector which requires not only a specific type of battery (9V alkaline) but also a specific model (in this case Duracell MN1604) to be used. I had a similar problem with a CO detector about a year ago (which came with a list of about 10 models that should...
  15. BillTre

    Smoke in Eugene, OR: See Where the Fires Are

    There has been a lot of smoke in and around the Eugene, Oregon area the last few days. At times today, the we have had 1/2 to 1/4 mile visibility. Other areas are worse. The smoke comes from a lot of fires in the state and nearby (duh). Those who are interested in this can look here to see...
  16. CassieFordham

    B How high does a wall need to be to block smoke?

    A smoker just moved into the mobile home next to the one I live in, and insists on smoking in his yard. I want to build a wall between us to block the smoke. I don't know how to calculate how high the wall needs to be, to keep the smoke from blowing into my yard. Can anyone help me to figure...
  17. F

    B What Are the Most Accurate Smoke Detectors and How Do They Work?

    What are the most accurate smoke detectors have you come across and can recommend and why? Are there different types of detectors (I want to avoid the radioactive ones but are others less accurate)?
  18. M

    I The manufacture of ionization smoke detectors

    Was reading the ATSDR Public Health Statement for Americium. It mentioned that higher-than-normal levels of americium could be in the soil near plants that manufacture these devices. It also said that if you live near such a facility you should "discourage your children from putting their hands...
  19. Janson Raymond Kenny

    Acetic Acid + Ammonium Hydroxide Vapours

    Hi! I work in the movie business doing Special Effects. To create smoke for some effects we use "A+B Smoke." It is simply a mix of Acetic Acid (Part A) and Ammonium Hydroxide (Part B). However, the smoke effects is created when the VAPOURS of these 2 chemicals mix in the air. The MSDS Safety...
  20. K

    Possible to make smoke without the heat?

    Hello I'm new here at Physics Forums and have been struggling with understanding how a simple pyrotechnics works, and thought I'd try you guys. As i understand pyrotechnics heat up, making them very hard to control and dangerous to people around them but is the extreme heat really...
  21. Garlic

    Size of Americium in a Smoke Detector

    Hello, A few days ago I tried to calculate the decay heat of Americium in a Smoke Detector, but as I was trying to find the volume it should have, my calculations showed that its volume should be really small (smaller than a cubic micrometer), but it was obvious that it couldn't be so small...
  22. S

    Can a 300W fog machine create a smoke curtain 5 meters high?

    Hi guys, I'm a student and I'm new to this forum. Currently me and my friends are having a small project for the upcoming stage performance at school. We are trying to build a smoke curtain. The system will have a fog machine with 300W power and some PVC pipes that lead vertically to 5 meters in...
  23. P

    Why can't I test a smoke detector with smoke?

    I just came across the user instructions for my smoke detectors and am surprised. I've attached a small section of the instructions. They're from a mainstream manufacturer and labelled with a British Kitemark. You can see that I'm not supposed to test it with flame, smoke nor heat, and the...
  24. F

    Why do some nuclear power plants have smoke stacks?

    There are a lot of nuclear power plants around the world that have smoke stacks, the kind you'd usually see at a coal fired power plant. Are they to release steam in an emergency, or are they some kind of exhaust system the plant uses, or something else? Most nuclear power plants in America have...
  25. Chris R

    Smoke Rising in Still Air: Physics Explanation

    Hi all, I have what I believe is a simple physics question. I was burning a sprig of incense in my apartment, and noticed that the smoke was rising from the burning section perfectly straight up into the air for a good meter, and then started to dissipate into the air. I know that a gas will...
  26. Jam 1959

    Automotive Wind tunnel to do smoke testing of my Formula Vee racing car

    Hello.I need help with wind tunnel.The test section is 2m x 2.5 m x 5 m long.How do I work out size of inlet cone.Thanks in advance
  27. bagofbones

    Reducing Secondhand Smoke: Inside or Outside?

    I have a silly problem: I live in a block of flats, and my neighbours who live one floor below me, always complains that I smoke tobacco. So I would like to reduce amount of smoke that reaches them. I have two ways, please tell me which one would be more effective: • I smoke inside, with opened...
  28. bagofbones

    Smoke smell in a flat below mine.

    Good day, everyone, I have an uncommon question: Man smokes in a balcony. Will the people, who are below him will smell that? Or just people who live above the man? I guess warm air is going up, but how about a smell, diffusion says that molecules are moving disorderly, so I completely lost my...
  29. A

    Medical Telling the Doctor you Smoke Weed

    If you tell your doctor that you smoke weed or other drugs, will he tell the police? What charges can you face? I tried to do some research, but I could not find a reliable source. If you are a specialist on this subject, please state so and indicate where you live.
  30. Greg Bernhardt

    Replacing smoke detector alarm battery help

    I know I've done this before but for some reason I am stuck. I have a smoke alarm where the battery compartment is being blocked by the permanent power. I can't disconnect or a monitoring alarm will trip (i think?). There is a great deal of tension here and any more force I feel will break the...
  31. AdityaDev

    Ring of smoke after bomb blast

    I attended the navy day celebrations and the marine commandos demonstrated a bomb blast by setting a time bomb in a small installation at the middle of the sea. The commandos dived from their boat and set the explosives from underwater. After the explosion, what I saw first was a cloud of black...
  32. Spinnor

    Want this job? React fast? Taking down smoke stack.

    BBC had video clip of a worker presumably weakening a tall smoke stack. Looks somewhat dangerous. See, https://www.youtube.com/watch?v=PaR4cjqJ3Is#t=21 Why weaken it? Why not just use explosives?
  33. Neptune2235

    Troubleshooting My Homemade Smoke Bombs

    Hi, Recently, I made a batch of smoke bombs using potassium nitrate, sugar, and baking soda (to regulate reaction speed). My first batch took about four days to dry which seemed odd, however, they produced a fair amount of smoke. For my second batch, I decided to put the potassium nitrate I...
  34. A

    How to avoid set off smoke detectors

    Hey guys, I have just moved into a new place for my university studies. There are smoke detectors in the apartment(kitchen living room and bedroom), I never had those things in apartments that I use to live. I am quite worried about the one in the kitchen, because I heard that while cooking a...
  35. MathematicalPhysicist

    Do you think that Grassmann used to smoke grass?

    Do you think that Grassmann used to smoke grass? :-) http://www-history.mcs.st-andrews.ac.uk/Biographies/Grassmann.html
  36. F

    Just how bad is inhaling smoke?

    It's been well established that inhaling smoke is bad for you compared to not inhaling smoke; I'm curious how various types of smoke inhalation compare. For example, 5 minutes of breathing smoke from an indoor wood fireplace with faulty ventilation versus the same time breathing from an...
  37. EVriderDK

    How to remove fog, created with a smoke machine (Glycol and water)

    Hey. I really want to know if it is possible in some way, to remove the fog created by a smoke machine. The fog is created from heating up glycol and destilled water at 300 degree C
  38. S

    What is the difference between IC BT66 and UM66?

    i am going to build this fire alarm. i got IC BT66 in place of UM66 . I want to ask that are BT66 and UM66 same or is their any difference of work. Also can anyone suggest any site where i can get internal circuits of the IC's UM66,TD2002,7805. thanks in advance . :smile:
  39. D

    Double slit experiment with smoke particles

    Homework Statement Suppose we wish to do a double slit experiment with a beam of the smoke particles of Example 4.1c (which is lamda=6.6e-20m). Assume we can construct a double slit whose separation is about the same size of the particles. Estimate the separation between the fringes if the...
  40. M

    Help Physics Project: Smoke Waterfall

    Homework Statement I have a presentation on our physics class and I have decided to demonstrate the phenomenon of Smoke Waterfall inside an airtight container. I saw my friend do this tons of times. It's really amazing but how can I explain the physics behind this trick? In general knowledge...
  41. H

    Human head gives off smoke when electrocuted?

    I heard that when any human being is executed by electrocution (for instance on an electric chair) afterwards, smoke comes out of his head (seriously). Why does this happen? I think it's got to do with the fact that the human head has a huge number of neurons and their is a lot of electrical...
  42. D

    Colorful smoke from burning WHAT?

    Sorry guys I am not an expert, but I wondered for my general use What substances do you know will burn in mild tempratures (4 to 40 C, let's say) simply in the presence of oxygen and fire (spark or surrounding fire) creating prominent colorful fire - hence different from white, gray or black...
  43. O

    How does smoking preserve foods against bacterial growth?

    Does anyone have any suggestions on how smoke kills bacteria? Thanks in advance for any suggestions
  44. O

    What kind of charges is within the smoke from cigarette?

    Positive or negative charges? Does anyone have any suggestions? Thanks in advance for any suggestions
  45. J

    Medical Is Second Hand Smoke Harmful Even If It Doesn't Cause Failed Urine Tests?

    I have a question regarding second hand smoke and its dangers, I hope this is the right place to post it. I have been told how dangerous second hand cigarette smoke is, I have also been told that it is impossible to fail a urine test due to inhaling second hand MJ smoke. So which is it...
  46. S

    Behaviour of smoke under pressure

    A 1 liter glass jar contains enough fuel to create 10 liters of smoke. This amount is known and irrelevant to the problem and is located at the bottom of the jar. A pump is attached to the top of the jar. A valve is also in place on the top. The jar is closed and pumped until 10 atms is...
  47. N

    Lighting a candle, blowing it out and relighting it by lighting the smoke?

    http://imgur.com/gallery/VtWhm - I've been trying this ever since I saw this .gif and it works. No idea why. Can anyone help?
  48. M

    I smoke. I like to lite cigarets with matches. It was long time since

    I smoke. I like to lite cigarets with matches. It was long time since today when I used lighter to light a cigarette. Smoke from the lighter, smoke from the cigar, also smoke of the matches was escaping gravitational pull. I never saw any research made on lighter (synonym) than gravity...
  49. S

    Heat / Smoke / Pressure in a confined box?

    Heat / Smoke / Pressure in a confined box?? I am a fireman with 15 years on the job. I am also an instructor at 2 different fire academies and within both my career agency as well as in my volunteer department. I often watch numerous videos and try to extract "teachable" moments. Recently I...