This inexpensive electrophorus set works great!
From Amazon: BUY NOW Electrophorus Demonstration Set
From eBay: BUY NOW: Electrophorus Demonstration Set
The container is just the middle part cut from a plastic water bottle, and the "hail" stones are Styrofoam craft beads:
From Amazon: BUY NOW Styrofoam Craft Beads
For Volta's Hailstorm to work, the beads must be coated with a conducting spray (here is what I used):
From Amazon: BUY NOW Staticide Spray
Wikipedia has a very nice description of the physics of the Electrophorus and how it is used to transfer electric charge.
Volta’s Hailstorm and Electrophorus: electrical forces due to electrostatic charge send foam beads flying in this version of the historic demonstration by physicist Alessandro Volta. The beads are covered with an electrically conductive coating allowing them to transfer charge from the environment to the plate of the electrophorus. The acrylic platform becomes negatively charged when rubbed with a paper napkin, but it is also an insulator so the charge on it can not flow on to the aluminum plate of the electrophorus. Instead the charge on the platform pushes electrons to the top of the plate (like signs repel) and touching the plate results in a spark that removes the electrons giving the plate a significant positive charge that will then attract the beads.
Craft sticke work great:
From Amazon: BUY NOW: Stick Bomb Supplies
Amazingly: There is a Wikipedia entry on Stick Bombs and their physics
Popsicle Stick Bomb: a form of simple tensegrity, the elastic potential energy of the bent sticks is dramatically released under application of a slight concussive force such as an impact with a table top- shown here in forward and backward slow motion (swipe to see three more explosions). Shown here is one of the simplest constructions with 5 flat sticks woven into a spring-loaded configuration held in place by friction and tension induced by the bending of the wood. A nice demonstration of energy conversion- potential to kinetic.
The Actuator mechanism is out of production but can still be found on eBay, comes with power supply, Expandagon kit, and connecotors that snap on to a Hoberman Spjere.
From eBay: BUY NOW: Hoberman Actuator
The spheres are still in production and come in various sizes and colors:
From Amazon: BUY NOW Hoberman Spheres
Hoberman Actuator with Sphere: This actuator mechanism creates kinetic art out of a Hoberman sphere, designed to smoothly expand and contract the isokinentic structure. The Hoberman sphere itself is a special assembly of foldable linkages consisting of rigid bars and simple hinges is kinematically over constrained- motion can only occur along the radial direction and the movement of any hinge creates motion in all the joints. The engineering and physics behind deployable space structures!
Get some of these grow-spheres here:
From Educational Innovations: BUY NOW Growing Spheres
Super Absorbent Polymer: poly-acrylamide polymer crystals are able to absorb up to 200 times their volume of water. Here seven small spheres, approximately 4mm in diameter, were immersed in water for three hours, after which they were slightly more than 23mm across. The final gel sphere is more than 99.5% water- and they bounce!
Get inexpensive small motors and accesories for DIY projects here:
From Amazon: BUY NOW DC Motors Kit
A DIY project to see if just shaking a bolt at the right frequency could make a standard nut rotate and fall off. Similar physics to the phase locking propeller toy featured in my last post. Motivated by videos seen on Instagram where a brass bolt is placed in magnetic putty and the nut mysteriously rotates up and off- now convinced that vibration is how that effect is produced. Here a small DC motor spins an offset mass to produce the vibrations.
Similar 3D prints available as fidget toys here:
From Etsy: BUY NOW: Gear Spinner Fidget Toy
Or print it yourself! (.stl files are available here):
Emmett Lalish Download: Gear Bearing
Refined version featured here by Don Stewart Download: Honeycomb Gear Bearing
3D Print Planetary Gearset: amazingly this gear set is printed assembled, with interlocking herringbone teeth. The gears will not come apart, in fact this design can only be accomplished by 3D printing the gears interlocked with each other. Designed and first printed by Emmett Lalish in 2013, and this version with refined precision and honeycomb by Don Stewart.
Created in my shop with these parts:
From Amazon: plastic rings, plastic sphere, blue paint
Inspired by the Phone Booths in the new Watchmen series.
Calling Dr. Manhattan: floating rings illusion device inspired by the recent Watchmen series. Two attached rings appear to roll in an impossible way around an orb, featured in a number of scenes on top of blue interplanetary phone booths in the new Watchmen series. Created in my shop with plastic rings and some blue spray paint.
Get this nice example of mystery braid here:
From Art of Play: BUY NOW: Impossible Braid Key Fob
Here is a great video on how to make the mystery braid
See other Impossible Objects in my collection.
Mystery Braid: challenge- how can three strands be braided if both sets of ends are connected? (swipe for reveal) A new addition to my collection of “impossible objects”, this leather key fob is braided from a single piece of leather, constructed by making two parallel slits but not cutting the ends. The solution is well known to those in the field of leatherwork- due to a twist of topology it’s possible to make this braid if the number of left strand over right crossings equals the times the right strand crosses over the left. Four strands braided this way is not mathematically possible, but 3, 5, or any odd number can be done!
Guage block sets can be a bit pricy, but some fairly inexpensive pieces and small sets can be found for demonstrations and such:
From Amazon: BUY NOW: Gauge Blocks
Wikipedia has a nice description of Gauge Blocks and the Phenomenon of Wringing
Wringing Gauge Blocks: two blocks of metal (not magnets!) will stick together by a process called wringing if their surfaces are flat to high precision- such as these gauge blocks found in most machine shops. Here two blocks are forced apart with a snap, and then wrung back together with the characteristic sliding motion technique. Gauge blocks are flat to less that one millionth of a meter and are used by machinists for precision length measurements and calibration. The science of the wring force remains somewhat a mystery and no one has yet found a fully excepted physics description- but we do know that blocks will wring in a vacuum and that the force can be up to 30 times that of weight of the blocks. Fun physics from the shop!
Get the 3D print files here:
From Thingverse: Make Now: Single String Tensegrity
Click here for more tengerity in my collection.
Single Strand Tensegrity: a vertical chain- when held under tension a single length of thin chain can become a rigid support structure. In this design four 3D-printed struts each act like an archer’s bow to stretch the chain under tension. Beads placed on the chain interlock with the ends of the struts. Design and .stl files by Ernie Condone and printed by Roger Key (thanks!)
Gallimum metal and a silicone mold to produce the spoon- available here:
From Amazon: BUY NOW: Gallium Mold Spoon Kit
Disappearing Spoon: the metal gallium has a melting point of 30°C (86°F) and will melt quickly when exposed to tea temperature hot water- or melt in one’s hand if handled too long. This spoon was made with a silicone mold (swipe to see process), and feels and sounds just like a regular spoon, except solid gallium is brittle and the spoon can shatter like glass if dropped. An amazing parlor trick as well as a classic and historical class demonstration.
Neodymium magnets will produce the largest gap when suspending a nail.
Please use exterme caution when handling these magnets.
From Amazon: BUY NOW: Neodymium Super Magnet
Magnetic Defiance of Gravity: a nail suspended between a chain and a powerful neodymium magnet. Ferromagnetic attraction over a distance of many millimeters, and a reminder of the presence of the typically invisible electromagnetic forces all around us. Make your own with a paperclip, string, and a refrigerator magnet- or get a neodymium magnet and see how massive an object you can suspend in air.
Glass divers available here:
From Amazon: BUY NOW Glass Divers or this complete set Cartesian Diver Kit
Inexpensive and fun diver kits to make in a bottle available here:
From Educational Innovations: BUY NOW Cartesian Diver Kits
Cartesian Divers: increasing pressure on the water compresses the air bubbles in the small glass vials filling them further with water making them sink. Pascal's principle states that any change in pressure on an enclosed fluid (such as pushing on the rubber cover) is transmitted evenly to every part of the fluid- the physics of hydraulic brakes! Named after the physicist and philosopher Rene Descartes.
Simiar diamagnetic levitation kits are available here:
From eBay: BUY NOW Diamagnetic Levitation Kit
Diamagnetic Racetrack: thin pyrolytic graphite sheets levitate above powerful magnets. A set of five concentric neodymium magnets, alternating N-S-N-S-N comprise the racetrack and form the trapping field. Diamagnetic substances develop temporary repulsive magnetic fields only when they are in the presence of a magnetic field from some other source. Graphite of this sort is the most diamagnetic substance known.
For this demonstration stronger magnets work best:
From Amazon: BUY NOW: Neodymium Magnets
Here is a good small turntable with bearings:
From Amazon: BUY NOW: Spinning Base
Magnetic Influence on Aluminum: physics puzzler- spin a magnet under a beer can suspended by a thread, and the can will turn. Why? Aluminum is not ferromagnetic, and as shown, magnets are not attracted to the can. So how does a spinning magnet influence the can to spin?
Answer: the can spins due to eddy currents induced in the conducting aluminum due to the moving magnetic fields underneath. The eddy currents make the can into a temporary electromagnet that then interacts with the magnets below according to the famous law by Lenz.
Get these 99.9% pure element Bi 83 cubes here:
From Luciteria: BUY NOW: Bismuth Element Cube
Many combinations of strong neodymium magnets will work, here are the versions I used:
From Amazon: BUY NOW: Cylindrical Neodymium Magnet
From eBay: BUY NOW: Tiny Neodymium Cube Magnets
See my video of other pure element cubes by Luciteria Science
Bismuth Diamagnetic Levitation: Element 83 (bismuth) is the most diamagnetic of the elements*. Here a small neodymium magnet is made to float between two 99% pure bismuth 10mm cubes which are held in precise configuration by friction with the parallel walls of the acrylic assembly I made. Diamagnetic substances only have magnetic fields of their own when placed in an external magnetic field from another source- here the tiny cube magnet supplies the field. Diamagnetic fields are pretty weak though so a powerful cylindrical neodymium magnet sits above the cubes and is adjusted to help lift the tiny cube magnet against gravity. *except for a special form of carbon known as pyrolytic graphite.
The bottle used here is from Voss Water: a nice cylinder and the labels come off easily. Amazon has the ingedients:
From Amazon: BUY NOW
acetone, blue glitter, food coloring, Voss Water
The density column I made for this video is based on blend of two ideas: this "science snack" from the exploratorium: Klutz-Proof Density Column and this ChemED X post: Blog of Prof. Tom Kuntzleman
See my Salt Fractionation post for details.
Unmixing Density Column: three liquids that won’t stay mixed! Acetone (dyed blue) floats on top of the higher density vegetable oil, which in turn floats atop salt water (dyed orange) which is more dense than oil. Acetone usually dissolves in water through hydrogen bonding interactions, but solubility can be altered. In a process called “salting out” a sufficient amount of salt is dissolved such that the water molecules, which are much more attracted to the resulting Na+ and Cl- ions (through ion-dipole bonds), will then ignore the weaker acetone hydrogen bonds. This results in the spontaneous separation of these three liquids no matter how well shaken up.
Neodymium magnets will produce the largest gap when suspending a nail or other iron rich objects.
Please use exterme caution when handling these magnets.
From Amazon: BUY NOW: Neodymium Super Magnet
In Defiance of Gravity: a 3 oz plumb bob in suspension between a chain and a powerful neodymium magnet. Ferromagnetic attraction over a distance of many millimeters, and a reminder of the presence of the typically invisible electromagnetic forces all around us. Sculpture: oak, stainless steel chain and hardware, neodymium super magnet, standard plumb bob tool. Iron filings in oil align and chain together to reveal the magnetic field lines of the equilibrium configuration.