Budget physics

Top Secret

This physics toy top is available here: 

From Amazon: BUY NOW Mystery Spinning Top

From eBay: BUY NOW Mystery Spinning Top 


The amazing green magnetic viewing film is also available: 
From Educational Innovations: BUY NOW Magnetic Field Viewing Film 

Here is the 1974 patent showing the very simple circuit of this device. The spinning dipole (the top itself) induces a current in one of the coils, and this current is fed to the base of the transistor turning the electromagnet on when the top is near. 
 

"Top Secret": this top will stay spinning for more than a week- because it is actually a motor! The top is a dipole magnet (as revealed by Magneview film) and the base has an electromagnet that gives the dipole a push when the top comes near the center. An ingeniously simple circuit consisting of only a battery, a coil, and a transistor, is activated when the spinning magnet nears the coil turning on the electromagnet to give a boost to the spin of the magnetic top.

Photochromic UV Bracelets

Get this set here:
From eBay: BUY NOW: UV Color Change Bracelets

You may also want an awesome UV flashlight like this one:
From Amazon: BUY NOW: High Power UV Light

Check out this: Photochromic Frisbee

UV Color Changing Beads: the photochromic pigment molecules in the white beads actually change shape when struck by UV light, and the new shape alters their absorption properties such that they reflect brilliant colors. The color is temporary- when removed from UV exposure, room temperature thermal energy bumps the molecules back into their original configuration, and the color fades back to white in a few minutes. Here a UV flashlight reveals that each bracelet transforms to a different color. 

Tornado Spheres

Get a set here: 
From eBay: BUY NOW Tornado Spheres

Get a concave mirror like the one in the video for less than $3 here: 
From Amazon: BUY NOW Concave Mirror  

And get a set of inexpensive colored lights here: 
From eBay: BUY NOW Color LED lights 

Tornado Spheres: two ball bearings welded together can be made to spin up to 2000+ rpm by the Magnus Effect using a stream of air. Shining three colored LEDs on the spinning pair produces an illusion of floating rings along with a second illusion that these rings are rotating and changing direction due to aliasing with the frame rate of the video camera (like the famous wagon-wheel effect).


Cartesian Diver

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.

MaBoRun Minis

Many styles to choose from- get a MaBoRun here: 

From eBay: BUY NOW: MaBoRun Mini

Similar devices here:
From Amazon: BUY NOW MaBoRun Marble Run 

MaBoRun Minis: rolling marbles doing tricks as gravitational potential energy is converted to kinetic energy. Three mini marble runs each with a battery powered means of lifting the marbles: 1) a belt driven gear, 2) a scissor linkage that translates the rotation of the motor into linear motion to lift the marbles to the top and 3) an Archimedean Screw conveyer. Two of these runs incorporate a simulation of decaying orbits with conservation of angular momentum as the marbles whirl down funnel shaped tracks.

Triple Pendulum Chaotic Fidget 

Get this chaotic fidget spinner here:

From Amazon: BUY NOW: Triple Pendulum Spinner

Triple Pendulum Chaotic Fidget: This interesting spinner is made from stainless steel and features three physical pendulums each mounted with their own low friction bearing. In slow motion one can see the kinetic energy and angular momentum is transferred from one pendulum to another as the entire device rotates, with some spinning rapidly and others rotationally at rest- the intricacies chaotic motion, characterized by extreme sensitivity to initial starting conditions, tiny differences in how the system is released leads to dramatically different outcomes each time.


Pop Pop Boat

Get one here: 
From Educational Innovations: BUY NOW Pop-Pop Boat 
From Amazon: BUY NOW Pop-Pop Boats 

Wikipedia has the details on the physics and history of this little steamboat toy 

Pop-Pop Boat: birthday candle powered, super simple steam engine named after the sound it makes when operating. The engine is just a metal box, heated by the candle, with two pipes coming out of it. Steam builds up pushing water out with an explosive pop- which then creates a vacuum sucking more water in to repeat the process. Patented in 1915 these were very popular in the 1940's.


Sprial Oil Drop Timer

Get one here:

From Amazon: BUY NOW: Oil Drop Timers

Spiral Oil Drop Timer: when this drop timer achieves its steady state the drops form with amazing regularity in terms of both the size of the drop and the spacing between drops. The physics of immiscible liquids, surface tension, viscosity, and gravity combine to produce these interesting patterns. 

 

Homopolar Motor

Fairly simple to make- here are the inexpensive supplies needed to make a few of these motors. 
AA batteries have a diameter of 14.5 mm, so a bottom magnet with a diameter of 15 mm is just right: 
From eBay: BUY NOW Neodymium Disk Magnet 

Wire that looks and works well is just 10 gauge ground wire. Inexpensive and available at any local hardware store-- or order a small quantity here: 
From eBay: BUY NOW 10 gauge Copper Wire 

Wikipedia has some good details on the physics of homopolar motors 

Homopolar Motor: a minimalist electric motor- battery, wire, and magnet. This type of motor does not need a commutator- the polarity of the electromagnetic coil does not need to reverse. The challenge with this design is balancing the coil to center on the battery as it rotates. A favorite DIY physics toy!

Dudeney's Dissection 3D Print

Get this set here!

From Etsy: BUY NOW: Dudeney's Dissection 3D Print

Dudeney's Dissection: an equilateral triangle canbe cut (dissected) into four pieces that will then assemble into a square. This 3D printed version comes as a puzzle- fit the pieces in each of two containers- a square and a triangle, which also makes it clear the two supplied shapes are of equal area. Fun fact: It is not known if a similar three piece dissection is possible. Also called Haberdasher's problem and described in 1907 by Henry Dudeney it is the only 4 piece solution known.


Elastic Equilibrium Puzzle

Get this puzzle here:

From Amazon: BUY NOW: Atomic Cherry Puzzle

Elastic Equilibrium Puzzle: six spheres held together by three plastic springs. When assembled each sphere exerts the same force on its four neighboring spheres, producing this equilibrium state only if all six spheres are used to balance all the forces. A fun configuration to analyze in a 1st year physics course- the Atomic Cherry by Brainwright puzzles. 

Glass Hydro-Top

Available in four colors and designs: 
From StemCell Science: BUY NOW: Glass Water Tops

Glass Hydro-Top: under centripetal acceleration a liquid will flow to create a cylindrical surface parallel to the axis of rotation. This blown glass dreidel contains a small amount of colored water that when spun resembles a blue gemstone banded around the rim. A unique design with fun physics!

Lissajous Roller 

Available from Pyrigan & Co.

From Etsy: BUY NOW: Lissajous Roller Illusion

Lissajous Roller: when viewing this 3D printed object from the side one sees a projection of a 3:2 Lissajous curve, but the object is actually cylindrical in frame and can roll towards or away from the viewer. When in motion a “dual axis illusion” is produced where the object appears to be rotating about a vertical axis. Invented by Bill Gosper and produced by Pyrigan & Co. 


Floating Yen

Aluminium 1 Yen coins are the perfect denisty to float as shown in the video:

From Etsy: BUY NOW: 1-Yen Coins

Floating Yen: the surface tension of water is strong enough to suspend the aluminum coin, and a trapped column of air in a second glass can submerge a portion of the surface with the coin. The 1-Yen coin has just the right mass and density for this demonstration. One of my favorite DIY physics demonstrations.

Repelling Marbles Puzzle

Get this affordable and fun kit here:

From Educational Innovations: BUY NOW Mystery Marbles Puzzle Kit 

Mystery Marbles Puzzle: a physics brain teaser (now available as a kit) what's going on here? Three glass marbles can move but stay separated in this liquid filled tube no matter the orientation- why do they not touch? Swipe for reveal of components. 

See also: Poly-acrylamide Polymer Vanishing Act