Ferrofluid is a magnetic fluid which can be manipulated using a magnet.
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Author Archives: emilyeifler
How to clean silver with aluminum foil, baking soda and hot water
Aluminum Foil Eagle Sculptures
Sarah Thibault is a San Francisco based artist. While doing mostly painting recently she has ventured out in to making sculpture. She showed several of these aluminum foil eagles her her recent MFA show. The foil birds are built on wire armatures and painted with spray paint. You can see her work here.
Acrylic on tin foil
Stumbled across this beautiful image on flickr of clear acrylic on tin foil.
Aluminum Foil Spark
Spark from three 330V 120 uF photo capacitors in series charged to 940V via SCholewiak.
Compound Parabolic Solar Cooker
Just the thought of experimenting with aluminum foil sent me searching for solar cooker designs. A solar cooker is essentially a reflective dish used to focus sunlight to cook food. Commercially they come in many different shapes and sizes but with a bit of geometry I think we can optimize a DIY shape for the best light collection. My first instinct was to use a parabolic reflector. A circular paraboloid can collect a large field of light and redirect it in to a focal point. This allows for far higher temperatures at the focal point than at any other point in the field.
The only problem with this shape of cooker is that it must be positioned to directly face the sun for optimal temperature. Theoretically the solar panel amplification dish design below could be used to create a solar cooker that would collect light even as the sun moved over time.
(via fossil freedom)
There are is a great how to for a compound parabolic solar cooker on instructables. For a simpler rectangular design that can be made with a cardboard box.
Making Aluminum Foil
Salt and Marble Mystery
Want to know how to get a marble from one end of a salt-filled test tube to the other? Or how to get that pesky toy from the bottom of the cereal box? Even if you have never thought about it, it is a interesting illustration. Go here for video (its not a youtube video so I cant seem to embed it here)
Here’s the experiment description:
“1. Fill the test tube 3/4 full with salt
2. Place the marble on top of the salt.
3. Seal the end of the test tube with a cap (or a cork). The trick is to get the ball from one end of the tube to the other, through the salt.
One might think that since the marble is much more dense than the salt, it will sink to the bottom when the sand is agitated. The opposite is actually true.
How does it work?
Hold the tube vertically with the marble at or near the bottom. As you shake the tube up and down, the marble will actually rise through the column of salt. Each time the tube is jerked upwards, both the marble and the salt move up at the same speed. Because the salt particles are lighter and smaller, they experience greater relative friction than the marble when rubbing against each other. This causes the salt particles to slow down faster. After each shake, more salt particles are packed underneath the marble, until it magically emerges from beneath the salt.”
via Steve Springer
Marble Optics
Marbles are a great example of optical lenses, optics being the branch of physics which studies that behavior of light especially when interacting with matter. Quarts balls similar to marbles were the original magnifying glasses. Polished to utter smoothness these clear spheres were used as early as 700 bc. Later Glass balls filled with water were used by the Greeks and Romans to similar effect. The above image, by Sarah Lazarus on Flickr, is a beautiful illustration of the light refraction properties of a glass sphere. The light from a flashlight passes through the sphere and is focused in to a bright spot on the floor on behind the marble. Below is a refraction diagram of exactly what is happening to the light.
