Applied Physics

This is a simple build of a Michelson Interferometer using the SpyNet Laser Tripwire . About a year ago, I accidentally came across this toy and noticed that it has a red laser and two adjustable mirrors. It also has a receiver that will sound an alarm when the laser beam that shines on it is blocked. Yes, I have reverse engineered the receiver—a rather simple circuit, really—and, of course, improved it and may post an article about it to demonstrate an SCR (Silicon-Controlled Rectifier). I requested a reviewer’s sample from Jakks Pacific but did not receive one, so I had to wait for an…

Scientists at the synchrotron PETRA III have investigated X-ray absorption of highly charged iron ions.  Highly charged ions - that is, atoms which have been stripped of most of their electrons - play an important role in astrophysics. Within the large accumulations of visible (luminous) matter in the universe, the highly charged state is the natural one. This is the case in stellar atmospheres as well as in the interior of stars, where temperatures of several million degrees Celsius rule. Highly charged ions also abound around exotic objects such as neutron stars or black holes. Before…

Oak Ridge National Laboratory researchers have developed a new oxygen “sponge” that can easily absorb or shed oxygen atoms at low temperatures.  Materials containing atoms that can switch back and forth between multiple oxidation states  are very rare in nature but useful in devices such as rechargeable batteries, sensors, gas converters and fuel cells. Many energy storage and sensor devices rely on this valence-switching trick, known as a reduction-oxidation or “redox” reaction. For instance, catalytic gas converters use platinum-based metals to transform harmful emissions such as…

In my previous article, you learned how to use the 555 test circuit as a cable tester. It can also be used to test whether different materials conduct or don’t conduct electricity such as plastic, glass, cloth, wood, a coin from your pocket, a house key, aluminum foil, or any number of materials from around the house. You can also use it to see how well you conduct electricity to demonstrate one of the measurements, skin conductance, of a polygraph, or lie detector. In the demonstration video I touch the snaps together to get a base line tone. Next I hold the snaps on the red and black…

In my previous article, you learned how to build a hot liquid level indicator for the vision impaired to help them fill cups with hot liquids such as tea or coffee. The 555 test circuit was used to generate a tone when the liquid in the cup reached the desired level--when the liquid level reached the red and black snaps of the Jumper Wires inside the cup. The liquid (my coffee) conducts electricity because tapwater contains small amounts of contaminants. Some of the contaminants include anions (these have a negative charge) such as chloride (250 ppm), nitrate (10 ppm), and sulphate (250 ppm…

In my previous article, you learned how to build the “The 555 Test Circuit.” We are going to modify the test circuit to create a hot liquid level indicator for the vision impaired to help them fill cups with hot liquids such as tea or coffee. To fill a cup with cold or room temperature liquid, the vision impaired person simply puts his or her index finger inside the cup to monitor when to stop pouring the liquid when it hits his or her finger. When pouring hot liquids from, say, a boiling teakettle, vision impaired persons would not want to monitor the liquid level with a finger since they…

Researchers can argue about the accuracy of old thermometers and how to pick the datapoints of numerical models, but radio waves can help clear some things up. The ionosphere, one of the regions of the upper atmosphere ionized by solar radiation, is used for the transmission of long-wave communications, like radio waves. And it turns out that radio waves reflecting back to Earth from the ionosphere offer valuable news on climate change. The strength of radio signals on the ground is a reliable indicator of temperature change above. A team writing in the Journal of Geophysical…

Snap Circuits is an educational toy that teaches electronics with solderless snap-together electronic components. Each component has the schematic symbol and a label printed on its plastic case that is color coded for easy identification. They snap together with ordinary clothing snaps. The components also snap onto a 10 X 7 plastic base grid somewhat analogous to a solderless breadboard. There are several Snap Circuits kits that range from a few simple circuits to the largest kit that includes 750 electronic projects. All the kits include manuals printed in color with instructions for…

By the time Sandy hit New Jersey and New York, it had been reduced to a tropical storm but its rare angle of approach still meant a lot of devastation. Environmentalists in New York are resistant to creating barriers against future storms, like subway doors that can prevent flooding, and seawalls, but the stories of two residential beach communities on the New Jersey shore provide compelling evidence. Bay Head and Mantoloking sit side-by-side in Ocean County on a narrow barrier island that separates the Atlantic Ocean and Barnegat Bay. What newspaper editors came to call Super Storm Sandy…

You have noticed the way water flows around boulders in a fast-moving river, creating areas of stillness and intense motion. It's possible to control the forces of fluid flow at the smallest levels by placing tiny pillars in microfluidic channels. By altering the speed of the fluid, and stacking many pillars, with different widths, placements and orientations, in the fluid's path, they showed that it is possible to create an impressive array of controlled flows. Why does this matter? Because such a method will allow clinicians to separate white blood cells from other cells in a blood sample…