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Hidden Mechanism of Fluorescent Bulbs

Visit the Exploratorium 

Hidden Mechanism of Fluorescent Bulbs @exploratorium: only half of this bulb is covered with the typical internal white phosphor coating- revealing the electron emitting cathode and eerie blue glow of an excited mercury vapor at low pressure. Energetic electrons flow from one end of the tube to the other, exciting the mercury atoms to emit their characteristic emission spectra, mostly just a bright blue line (436 nm) and green line (546 nm) as seen here with a diffraction grating. Importantly there are also two strong invisible UV emission lines, which are absorbed by the glass in the non-coated section, but are used to make the bulb appear white by stimulating various blends of phosphors, which then emit a wide spectrum of wavelengths/colors- revealed here by an identical diffraction grating. A rare look at the complex physics and engineering of this common light source. 🌟 With thanks to the Exploratorium! 


The Lollipopter

Four styles to choose from: 
From Amazon: BUY NOW: Lollipopter Kinetic Art 

The Lollipopter (The Helicone): one of my favorite interactive kinetic sculpture designs. With a bit of practice one can master the transformation in both directions: A snap of the wrist imparts angular momentum to the "petals" which then rotate until an internal mechanism stops their motion with predetermined spacing- a helix transforms to an abstract pine cone. A second snap of the wrist in the opposite direction returns the helix. A creation by artist John Edmark. 

 

Sand Paperweight Toy

Available from these fine sources: 

From Amazon: BUY NOW Sand Globe Toys 

From Amazon: BUY NOW Sand Globe Toys: Winter Theme

A common version of this toy is for football fans: 
From eBay: BUY NOW Sand Football Paperweight Toy 

Wikipedia has a nice introduction to the amazing world of granular material science 

Sand Paperweight Toy: physics of granular materials- matter with unique properties between those of solids and liquids- as demonstrated with this simple toy. Granular materials, such as the sand in this toy, flow but also stack with a characteristic “angle of repose” as can be seen here as pyramid like ridges that form over the images of penguins. 


Mini-Lollipopter

Available here:

From Amazon: BUY NOW: Lollipopter Kinetics

From eBay: BUY NOW: Lollipopter Kinetics

Mini-Lollipopter: new smaller cousin of one of my favorite interactive kinetic sculpture designs. A snap of the wrist imparts angular momentum to the "petals" which then rotate until an internal mechanism stops their motion with predetermined spacing- clockwise rotation transforms a helix to an abstract pine cone, counterclockwise returns the helix. Created by @john.edmark.

The ΦTop

Professor Brecher has a limited supply of these "golden" (brass) versions of this top available on Etsy 
From Etsy: BUY NOW PhiTOP in Brass 

The ΦTop - Golden Version: spinning things have surprising physics! This unique top is made of solid brass in the shape of a prolate elIipsoid- and the name of the top is derived from the following design requirement: the ratio of the semi minor (short) axis to the semi major (long) axis is made equal to the mathematical constant the golden ratio φ (phi). Invented by astrophysicist Kenneth Brecher, this top stands up vertically (when spun with sufficient rotational velocity) due to physics similar to that of the tippe-top. The concave mirror keeps the top from wandering off and the glass surface has minimal friction allowing the top to spin for a long time- this video shows various stages of 8 minutes of total spin time.

Iron Filing Field Detector

This device and similar ones available from these fine sources: 

From Amazon: BUY NOW Magnetic Field Demonstrator Kits 
From eBay: BUY NOW Magnetic Field Demonstrator Kits 

Iron Filing Field Detector: visualizing the invisible- the magnetic field lines around a dipole bar magnet. In the presence of a magnetic field, ferromagnetic materials (such as iron) temporarily become magnets. Here the iron filings become dipole magnets and link up and align like tiny compass needles to follow and reveal the magnetic field lines associated with the permanent magnet underneath. Viscous silicone oil temporarily keeps the iron particles suspended yet allows for rotation and repositioning under the influence of the magnetic field.


The Galton Board

Available here: 
From Amazon: BUY NOW 
Galton Board 

The Galton Board: 3000 steel balls fall through 12 levels of branching paths and always end up matching a bell curve distribution. Each ball has a 50/50 chance of following each branch such that the balls are distributed at the bottom by the mathematical binomial distribution. One of my favorite finds of 2018! An elegantly designed modern version of the Galton Box invented by Sir Francis Galton(1894) to demonstrate the Central Limit Theorem - showing how random processes gather around the mean. In addition the number of balls in each bin can be predicted by Pascal's triangle (printed on the face over the pegs).

Wimshurst Electrostatic Generator

Get this inexpensive version that makes big sparks!

from Engine DIY: BUY NOW: Wimshurst Electrostatic Generator

Wimshurst Electrostatic Generator: this device uses two counter rotating disks of metal pads to separate charge via induction. The repulsion felt by electrons as the triangle plates pass by each other pushes charge to flow across two conducting rods, one on each side, which allows the charge to stack up. This excess charge is then stored in old fashioned cylindrical capacitors (Leyden Jars) until the resulting 30,000+ Volts is achieved to jump the air gap. This device goes back to 1883- invented by James Wimshurst

Double Radiometer

Get this beautiful two layer radiometer here:

From Mr. Sci: BUY NOW: Double Radiomenter

Single fly radiometers available from these sources: 
From Educational Innovations: BUY NOW Radiometer  (with disk shaped vanes)

A wide variety available here, including some nice blown glass displays: 
From Amazon: BUY NOW Radiometers 

Hundreds of options on eBay: 
From eBay: BUY NOW Radiometers 

Double Radiometer: a beautiful new version of this classic physics toy with two rotators enclosed in the same partial vacuum chamber. Light heats up the vanes which then heat up the very thin gas left in the bulb- the black side of the vane is hotter and any gas molecules that comes into contact with the black fly off at a faster speed imparting impulse to the rotor. The bottom rotor has black on the right side of each vane and rotates clockwise, the top rotor has black on the left sides and thus has the opposite rotation.


Euler's Disk

Get one here: 
From Educational Innovations: BUY NOW Euler's Disk and Accessories 
From Amazon: BUY NOW Euler's Disk 

Wikipedia has an excellent introduction to the physics of Euler's Disk 

Eulers Disk: (best with sound on) this toy exhibits the motion of a “sprolling” coin, a motion that combines spinning and rolling. Designed with a large mass and very smooth edge, this device takes close to 3 minutes to come to rest- and amazingly, the contact point between the disk and the mirror can reach a speed of more that 200 mph! This video catches the first and last parts of this 2 minute and 42 second run, with two cuts to 240fps slow motion to show the curious motion. Watch the end with the sound on! 

Sp!n Top

Get a Sp!n Top here- four colors to choose from:

From Art of Play: BUY NOW:  Sp!n Top

Sp!n Top: once set into motion the eye only perceives the punctuation mark ! in the center of a ring, with the vertical line seemingly suspended in space above the dot. The rate of spin is above the flicker fusion threshold of human vision, and the crossbars become blurred out and invisible- the effect is even more pronounced in person (hard to capture on video). Physics and psychophysics combine to produce this wonderful illusion!


Hexa Sphericon

Sphericon and Hexa-sphericon: beautiful works of art in metal- available here!
From the Matter Collection: BUY NOW The Sphericon (Hex and Regular) 

Hexa-Sphericon: Sphericons are unique solids that roll in such a way that every point on their surface comes in contact with the plane- following the path shown here with white paper. Solids from the sphericon family all have one side and two edges. Each sphericon is based on a regular polygon, with the basic sphericon derived from a square, and here- a more interesting case with more complex rolling motion- from a hexagon. 

Orbit Spinning Top

Get this 3D printed top here:

From Etsy: BUY NOW: Orbit Spinning Top

Orbit Spinning Top: asymmetric in shape but perfectly balanced about the rotation axis, this beautiful stainless steel 3D printed top will spin for a couple minutes. As the top slows down interesting aliasing arises as the angular velocity changes with respect to the frame rate of the camera. 

Tension Suspension: Tensegrity Scuplture

I made this device from these components:

From Amazon: BUY NOW:  heavy guage copper wire (for frame), inexpensive necklace chain (for connections), and hobby wire (to fasten chain to copper frames).

Check out these other Tensegity toys I've posted. 

Tension Suspension: an interesting take on tensegrity where one heavy wire frame seems mysteriously suspended above another. This sculpture features strings (chains used here to make it look more dramatic) in tension equilibrium, with the top wire frame hanging from the bottom frame by the strand in the center, and the other three strands in tension to keep it from tipping over. This configuration is related to the concept of tensegrity invented by Kenneth Snelson and made famous by the architect Buckminster Fuller in 1949.