The Physics of Bubbles

hi I'm Michele I'm a PhD student at Cornell and I study physics and for the past five years I've been running a physics of bubbles workshop but since we can't meet in person this year I'm going virtual so this should be fun okay I'm gonna start with the bubble basics to make a bubble you need a few components you need the bubble solution you need a site on which the bubble to form in the biz we call this a nucleation site and lastly you need a force to push that solution through the site okay I think we have our bubble basics down next we're going to study bubbles in their natural environment what I have here is Seltzer live and before I do anything I'm gonna just look in my glass and see where the bubbles are forming and I don't know if you could see but the bubbles are all forming on the sides in the bottom of the glass and the reason that is is the surface is rough and that roughness provides nucleation sites for bubbles to form to decrease the force required to make bubbles one way to do that is to decrease the surface tension of our liquid now soap and bubble solution which is just soap water is something that reduces surface tension and if I pour bubble solution and to my seltzer water it creates these this cascade of bubbles because the surface tensions reduced making easy to form bubbles and I made a delicious beverage so surface tension is a really fundamental and interesting concept that's kind of hard to wrap your head around but you could really just kind of think about it like regular tension so this is a rubber band when I pull the rubber band down it wants to go back up the great tension and increase this effective force I have this little wand and string that I made myself wind and if I pop the bottom part it creates this effective force to that the string wants to go up for my last seven demonstration of surface tension I'm gonna take some milk this is actually almond milk because I'm more of a alternative milk type of gal but any white beverage will do I'm gonna drop some food coloring in it there's red here's green and yellow and what I'm gonna do now is I'm going to take a q-tip I am and I'm going to take my soap and I'm gonna soap up that q-tip and I'm gonna dip this q-tip into the food coloring creating these fun starburst patterns before we go go back outside for our final demonstration I have a quick demo to show you the inside this is the disappearing bubble it's kinda hard to tell but it looks like someone took a slice off the top of the bubble right there the reason we see bubbles is through a process called thin film interference and what's happening here is the bubble is getting so thin at the top that the light is no longer reflecting off of it it's too thin it's just transmitting right through giving the illusion that it's disappearing so we're used to bubbles being spheres but they don't have to be bubbles get their shape from a process called minimal surfaces and while a free bubble will always take on a sphere you could get different shaped bubbles by providing fun shape wands and mathematics will always determine the how to minimize its surface area too and what shape the resulting bubble will take oh this one's really cool it creates these bubble edges in like a bubble for text which we're not used to seeing but my favorite wand is this cube one it's a bit of a process to set up but and I get made this suspended cube of a bubble in this frame so yes you can make a cube bubble without breaking any laws of physics

Channel: EYH at Cornell

Views: 268

Rating: 5 out of 5

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Id: ExotFVh0RFE

Length: 6min 12sec (372 seconds)

Published: Fri Apr 17 2020