Bruce, just a hypothesis. If the sand particles rub against each other as they fall, especially when falling through the nozzle, charges will be transferred and some will become positively charged, others negatively charged so in the presence of the charged strip, some of the sand grains will be attracted and others repelled. Perhaps you could collect the falling sand in a metal container attached to an electroscope and determine its charge. Make the metal container small enough and you could collect attracted sand or repelled sand. My thinking is based on the knowledge that sprayed water generates static charges. In the 1960s a number of very large oil tankers exploded whilst their tanks were being cleaned by high pressure sprayed water. Research showed it was a result of static discharge (as in lightning) caused by charges generated in the sprayed water.
A variation of lord kelvin thunderstorm, but with sand. One hole through which sand falls with two insulated wire rings directly below but side by side. With each ring connected to a metalic bucket below the other ring. If sand particles rubbing against each other displaces electrons to some by stealing from others, then they will fall into a bucket creating an imbalance that charges the insulated wire rings one way or the other. The newly charged rings will now attract opposing charges and repell like charged sand particles for the bucket directly below to collect. And charge the opposing ring.
The attraction occurs because the presence of either charged strip produces a polarization In the particles. This polarization then demonstrates the interaction/attraction. This is why you observe the attraction. Repulsion can only occur if the particles are charged, so we can assume that most of them are neutral. The water and comb trick is an excellent example of this as well. Love your ideas and videos Bruce. I’ve been a fan for years and I owe many of my lab activities to things you’ve shared to your community of science educators and enthusiasts alike.
As for why the sand spreads both ways, I hypothesize that some of the sand particles are negatively charged while some are positively charged. If an individual particle is positively charged, it will repel from the positively charged object and attract to the negatively charged object. Vice versa with the negatively charged particles. I have no clue if this is correct or not, but I would imagine a simple test verify this. Using the stream of stand, bring a positively charged item next to the stream and collect the bits of sands that fall away from it. Using the collected sand, repeat the process with both a positive and negatively charged object. If the collected sand particles repel from the positively charged object and are attracted to the negatively charged object, then my hypothesis may be correct.
I think the sand generates a lot of friction between the different grains causing individual greens to become charged negatively or positively so the Stream falling out the bottom of the bottle it’s both positively and negatively charged and can react to both simultaneously. Also most substances have differential throughout there volume. Salt and sugar is no different and when it transitions from Stationæry to freefallThose differently charged particles are free to separate.
Thank you, Bruce Yeany! If the sand is spreading like a fan, is it because the charge on the strip is pushing like charges in the sand away and drawing opposite charges in the sand to itself. This would suggest that we can a.) collect the two streams of sand in separate containers b.) pure the two streams of sand near one another and c.) these two streams of opposite charge should be attracted to each other and form one stream of sand.
Answer to the question of why the streaming particles spread out The given is the presence of a strong static field - a monopole. Another given is that the particles are not a fluid electro-static fluid - they are electro-static islands in an insulating medium of air. If the particles were to equally polarize in the field (on-off only,) some other behavior might result. But because the field strength varies with the square of the distance (or could vary more or less, but vary) - the individual particles are both attracted to the charge source (the object) and repel each other, also in proportion to the distance. Without doing the full math, there are two components to the charge, one attracting to the source and one repelling to the particles and mass-particles. The net charge (the sum of the equation for each particle) varies, creating a deflection force that varies by particle distance to the charge source object. The visual effect is the real-time sum of all equations, which could be shown as a several-factor time-integration formula. I won't do this. ☺ In addition, a similar but simplified effect can be seen in the visual behavior of the hair and the balloon.
I like the demonstration with the 2x4 and the pvc pipe. I may have to "steal" that. I've never thought of using a can either. So simple. The sand is great too - a good upside down model of an electrostatic precipitator. I usually use a thin stream of water to show polarisation and deflection.Thank you for sharing.
Hi Andy, glad they can help, I have some more good ones in part two and then will tackle the steam of water in a future one. I was surprised by the flowing particle streams. It was something I tried in the middle of making the video and I expected the particles to be attracted to a charge somewhat like the flow of water, didn't expect to see half of it repelled at the same time.
I wonder if there is some polarisation of the charge as it comes out of the nozzle. It's hard to tell from the video but there seems to be a greater separation of the sand particles than might be expected just from the fall. I think there is some sand building up on the outside of the nozzle which suggests a separation of charge. The charged rods/pipes you are introducing at the side are attracting some charges but repelling others. I wonder if the container the sand is stored in might make a difference?
I think maybe the asymmetry in the salt nucleus allows more of the particles to move towards to the charged object than away from it. Perhaps there is variability in the clumps of compounds where some particles are less ubiquitously distributed and more orderly.
Excellent show of classic electrostatic experiments. You asked why the sand particles spread out with either charge polarity. When the initially neutral sand particles fall thru an electric field, the individual particles by induction each acquire the same polarity charge. Thus the particles will tend to repel each other and tend to spread out. The same action occurs regardless of the polarity of the inducers used. Looking at 10.08 minute, it can easily be seen that the particles even after leaving the exit of the inducers are still spreading out (even against the tug of gravity), clearly showing that the repulsion of each particle is very significant regardless of inducer polarity at the start. A somewhat similar effect can be seen with a Kelvin water drop electrostatic generator. There, if the falling water is a steady stream the machine will not run. But if the water is broken into droplets it does run. As the voltage rises you can see the "spreading" of the droplets just like in your experiment here.
The falling powder demonstration was a spur of the moment idea and was made up while in the middle of making the video. I was quite surprised by the results. I figured that the particles would be charged through induction the same as on the table. I thought that since the induced charge on the sand would all be the oriented same way, then all the particles would be attracted to the charged strip, didn't account for the particles pushing against each other. I noticed that the particles spread out slightly before any introduced external charge but accounted for that by jostling of the particles as they are falling, I didn't attribute it to electrical charges on them. When I posted it, I really didn't have time to work through the results. Currently, I'm trying several variations on the bending of water streams and the results give me more questions about possible explanations than I have answers, it should be an interesting video and I look forward to seeing comments on it.
Excited to learn what you find in your investigations. Much of my lab equipment was lost due to a barn fire caused by a giant "electrostatic spark" known as lightning. As I slowly rebuild I am very dependent on others research experiments such as your self for a while. Thanks for sharing. I did manage to save my 1940's capacitive vane type lab quality electrometer.
@@YeanyScience I think the spreading out of the particles is a purely mechanical effect. Like water draining, the stream acquires a vorticity. The particles are inductively attracted to the charged object, acquiring by Newton's Law a radial acceleration away from the stream. However, by the time they have moved an appreciable distance radially, they have also moved tangentially and as such may end up traveling both towards and away from the charged object. - Les Virany Hunter College
but WHY does your hair give off electrons when you rubbed the balloon on your hair?? Whyyyyy do the electrons transfer in that example, and lets say, when you go down a plastic slide?
If you made a motor that had PVC for coils and a can as a core and the coils were positioned 30 degrees relative to the core would it make the can spin this question has been in my head for quite sometime you seem like the right person to ask
it logical for the sand to spread out as a charge is brought near it that's because for example if +ve charge is used it polarizes the sand making one side ( next to the +ve charge) -ve and the other end positive so the positive charges repel and the opposite charges attract making it spread in different directions.
I never saw a demo with sand and static charge before, Bruce. Cool! Sometimes static attraction is a problem with the foam gliders and deflecting boards--particularly in the winter when the air is dry. Wiping the board with a damp cloth usually takes care of it, but that got me wondering about the science behind the anti-static sheets that people put in the clothes dryer. Such as: do they remove charge or do they prevent it from forming in the first place?
Hi Slater, the falling sand results were totally unexpected. It was something that I put together as I making the video. I had expected the sand to to attracted to the charges just like a stream of water but was surprised when they spread out, not sure why. Offhand, I'm not sure of the chemistry behind the anti-static products but that might be fun to explore next year when we tackle this unit of study.
As for the electrical discharge, when the body rubs with the carpet, it loses electrons, and when the body touches any metal surface close to it, such as a door handle, for example (the bonding forces of electrons are weak) the electrons will move from the metal surface of the human body to compensate for the lack of electrons in it. The question is why does a positive charge not appear on the surface A metal that has lost its electrons
My take. Aligned particles that are polarized all in the same direction attract each other with a force that is inversely proportional to the fourth power of their distance (dipole-dipole interaction). All the particles within the stream are very close one another, so this force is stronger than that generated by the strip, even though this would decay with the third power (charge-dipole interaction). These forces within the stream push the falling particles that were initially closer to the strip towards the particles that were farther apart from it and viceversa. This would also cause many collisions within the stream. The result is that the stream to diverges - asymmetrically. Symmetrical spread can be achieved with the two strips of opposite charge placed on opposite sides of the stream as you showed. A different, more obvious, symmetrical spread can be achieved with two identically charged strips. Is this making any sense to you?
Just a guess, and I could be totally wrong. The small particles have so much surface area that even though they aren't good conductors, they are giving off or taking on electrons through the air, becoming similarly charged. So they are attracted to the source of the charge but repelled from one another.
The sand is made of particles of different minerals, some more positive or more negative. That's why some particles of sand are attracted to the static rod and others are repelled.
I am going to guess that the falling sand by itself isn't charged -- not much anyway. You can test this by using a neutral rod. If that doesn't have any effect on the falling sand, then there is no charge in the sand. If this is the case, then my explanation for the spreading of the sand stream is that tiny clusters of multiple sand particles that are inductively charged get randomly split due to collision, and the "daughter" clusters are afterwards oppositely charged. Which then move to the opposite sides of the stream.
I have other videos on youtube about static electricity and discuss the triboelectric series, it will determine which type of materials at better at gaining or losing electrons
Hi! Great video that inspired some question, if I may: 1. Why, when the balloon touches your hair, is there a transfer of charges, but If it touches the wall there is no transfer? Is it because wood is in the middle of the series and doesn't really accept or give up charges? 2. How do you discharge (neutralize?) the objects and use the energy? Do you use copper wire from the pvc pipe to a capacitor terminal? What about the opposite terminal, does that get connected to the opposite object? 3. Could you charge a capacitor with a pvc pipe and silk? Could you fill it to maximum with one pipe and repeated applications or would some sort of series/parallel setup be needed to overcome voltage issues? Thanks for all your wonderful videos and sharing these awesome demonstrations!
1) Friction between two different insulating materials strips some outer electrons off one surface depositing it on the other. Generally the more you rub them the more electrons get stripped untill they start stripping electrons from the air. Whereas ballon induction with simply once touching the wall may still see a few electrons transferred from a few spots where they get really close but overall, very little electrons are transferred leaving either a bulk abundance or lack of electrons. The other two I'll sugest you google the terms for a full answer. 2) Induction machines like say the whimshurst use electrostatic induction between conductive plates. 3) you may want to look up electrophorus.
Is it possible that the sand, as a whole, is neutral, but that in actuality each of the particles is distributed on a scale of what its charge actually is. Thus, when you place a static charge near them, some attract, some are relatively neutral and some repel. I wonder if you could set up some type of sorting rig that would allow the sand particles to fall into a grid that would sort the particles into (generally) like charges. since the sand behaves this way even when laying on the table (some attract and some repel) it leads me to believe that it's not only the falling through the funnel that charges them.
There was a lady in liquor production she stills of exquisite construction the alcohol she did boil with magnetic coils she said "that's proof by induction!"
Wait, I don't understand how the electrons on the wall are repelled by the presence of the negatively charged balloon. The electrons on the wall aren't delocalised right? I thought only conductors are able to exhibit this behaviour
Even after being rubbed with the balloon your hair is as neutral as the wall. And that because the hair is far to be a perfect insulator and the charge is spread into whole body and then down to the Earth. You can easily verify that: if it would charged it would be attracted by a neutral metal body, as the balloon is.
The charges aren't generated, just separated. In these specific instances, protons don't move and it's just the absence and presence of electrons creating the respective attraction and repulsion. When you hold a negatively charged piece of PVC pipe close to a soda can, the negative charges move away and the protons push towards the PVC pipe, as shown in the video. If you want to take a look at what specific materials attain what charge when rubbed together, search up a triboelectric series chart. The further away two materials are on the list, the larger amounts of electricity you're going to get, and it'll tell you what gets charged to what. Its relatively easy to navigate.
How far will the static electricity from plastic start to tske effect? I'm using a full plastic table and my pc is near but not on the plastic table. Will the static electricity from the plastic table damage my pc components?
When i start rubbering a material with a izolant. The izolant take electrons, and the material become pozitive charges. *But how i can get the material neutraly charge? How i can take the pozitive charges??*
🤓 I’ve spent my entire life studying and unlocking the secrets of electrostatic. You missed or overlooked some key elements about why both positive and negative fields can act the same. Just know that fields can change the other field to become the same field. This causes mode of attraction to suddenly repel. More so, both gravity and electrostatic have one thing in common. What would that be? 🤔 And an electrostatic field can do something that gravity cannot. What would that be?🤔 Do you know the answer to both questions? If so, tag me below with your answer please. I’ll come back a give you my answer once there are at least three valid attempts to answer my two questions. Actually the answer is so simple that you most likely will kick yourself in the ass if you don’t know the answer off the top of your head. The reason I am asking this question is because the implications of what the answer is, implies new possibilities, and a greater understanding the electric world that engulfs us, and beyond the stars. The day gravity is understood, that the formula for gravity will be so simple, it will account for why the answer has been overlooked for so long. - Albert Einstein The same goes for my two questions. For they unlock the answer to an age old question since man first questioned the natural laws of nature.
Both gravity and electrostatic have one thing in common. What would that be? 🤔 In short, their equations of attractive force are analogous for distance. Attraction between 2 masses gets exponentially stronger as the distance between them diminishes. Likewise for the attraction between opposite charges. And an electrostatic field can do something that gravity cannot. What would that be?🤔 It can pass through massive objects? ...Potentially unaffected if the massive object is non-ferrous.
The magnitude of electrostatic force depends on the distance between the bodies. Electrostatic field can attract as well as repel. Gravity does not repel
if you did the aluminum can one but make it like a horse and carriage so that the pvc pipe is indirectly attached to the can and the can has a axel through it. will the can still follow the pipe?
Bruce, I was wondering could this be used to bend an air stream towards a wind turbine? Could it be used to tailor the airflow over an airfoil like a airplane wing?
Do you have any demonstration video about there statement"If you rub glass with silk,silk and glass will attract reach other"?By the way, thanks for this great video.
Friction gets the electrons excited, holding more energy. This causes them to move farther away from the nucleus and easier to leave their place and into a material whose orbit will accept them. THAT material will now be more negatively charged, attracting the vacated positively charged material.
He looks up the combination of materials in the triboelectric series. Some materials are known to have a bias for gaining electrons, other materials are known for having a bias to gain electrons.
Hello Rohankurmar, Good question. It is summer time and more humid than I would like, with a lot amount moisture in the air, the pieces lose their charges much quicker to the air in the room . I did have a dehumidifier running in the room which helped.
HI Resonanttheme, thanks for the additional information, I think I'm going to give this some more tries. I have a Lord Kevin water drop experiment that I've had for years and years but haven't gotten around to doing a video on it yet. It is on my list of items I want to get to, but it would be great if I could make some variations to it.
That's the spirit. Thinking of that "copper filings falling from a copper funnel" I happened to see some large bottles/jars of both copper and zinc plated steel BBs at an Academy sporting goods store that seemed like something funny to play with in the handy 6000 shot packs. There're many sources of metallic grains to be sure, BBs just struck me as something quirky for some future use. Anyway I suspect that there are intriguing variations on a theme one could come up with these Lord Kelvin's realms. If only you could make a heavier than air machine out of one. ha www.nasa.gov/audience/formedia/speeches/fg_kitty_hawk_12.17.03.html
Sir every time I get outta the car I get a shock, I’ve tried a lot of stuff touching the body while getting out, let my foot touch the ground first, other things also, can you please help.?
Ranjit There's a guy on RU-vid who made a static discharge device with a resistor (it's very small) just look up 'static discharge tool' or (something like that).
oh my! I'm puzzled over the sand behaviour, so weird! and you give no explanation to it? what are you trying, make people think? are you crazy!? ;) Sand might charge while falling down by rubbing grains with each others, as sand usually are different kinds of materials, they might have different triboelectric values, then some get positively charged some negatively charged, then grains can be attracted or repelled by a charge... if by doing so, you separate different types of grains I think they should be somehow different... Also the confetti, seems some pieces are attracted, and instead of sticking to the insulator, they jump right off, as if they have taken more charge than the one needed to be neutral, then they are repelled...
Hello Sordnay, I made up this demonstration as I was making the video and the results were not what I expected. It happens with all three materials, sand, salt and suger. Unlike the paper pieces, the sand being repelled never comes in contact with the strips. I didn't have an explanation that I was satisfied with so I'm hoping someone else could help me out here.
I always understood electromagnetism as a relative thing..... it was never a question of "but the other one is neutral", there is only "a is greater than b"
+Bruce Yeany (Yeany Science) sir I comment on many big youtubers but you are the only one who have time for their subscribers to reply thank you so much !!
