Static Electricity Demonstrations Part one Induction // Homemade Science with Bruce Yeany

Part One: Several examples of static electricity are shown in this first part with a concentration on explaining the basis of inducing a static change on insulators verses conductors.

Note on the falling powder demonstration: This was something that I discovered as I was in the middle of making the video. I was quite surprised to see the powders spread out as I was expecting to see it all being attracted to the charges. I would love to hear explanations as to why this is happening.

Part two will be posted next week

Part two will give more examples of static electricity demonstrations and will examine the difference between induction versus conduction.

[pierrecastille]

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.

[beefsoda]

your demonstrations of the science are always incredible and fun. thank you for all the effort you put in for us.

[DivineMisterAdVentures]

The phenomenon of "STATIC INDUCTION" explains all my relationships just fine.

[Marween]

This is the kind of teacher I like at school really fun watching him demonstrate science!

[MTLLik]

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.

[JysusCryst]

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.

[hascleavrahmbenyoseph]

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.

[oreo]

This actually helps alot and I low key got 25/25 in My exam like i just watched the video i didnt touch the book thanks

[Samperdog]

Thank you! I'm teaching induction and don't have the supplies to do this in my class so I will do the next best thing and show this to my class.

[duramax]

Come on people give this man a thumbs up every video.

[ryanhorvath]

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

[brandonyoung-kemkes]

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.

[sciencetoymaker]

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?

[spartan]

Thanks a lot sir for your precious demonstration I recommend my students to watch your video for practical knowledge, Sir your efforts are great.

[ericr]

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.

[Vastafari]

but WHY does your hair give off electrons when you rubbed the balloon on your hair?? do the electrons transfer in that example, and lets say, when you go down a plastic slide?

[ruggerogabbrielli]

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?

[AndyCPugh]

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.

[Vanwild]

What make glass and PVC pipe have different charges? Or is it what u rub it with?

[DivineMisterAdVentures]

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.