Applied Physics

Many people know about ultrasound because of its popularity in prenatal imaging - grainy, grey outlines of babies made using reflected sound waves. A new 'acoustic diode' could dramatically improve future ultrasound images by changing the way those sound waves are transmitted. The theoretical framework for an acoustic diode achieves a one-way transmission of sound waves much the same as an electrical diode controls the one-way transmission of electrical impulses. The one-way flow of sound would provide brighter and clearer ultrasound images by eliminating acoustic disturbances caused by…

Active camouflage update. In a Harvard School of Engineering laboratory test, a team of applied physicists placed a device  with a new coating that intrinsically conceals its own temperature to thermal cameras on a hot plate and watched it through an infrared camera as the temperature rose. Initially, it behaved as expected, giving off more infrared light as the sample was heated: at 60 degrees Celsius it appeared blue-green to the camera; by 70 degrees it was red and yellow. At 74 degrees it turned a deep red—and then something strange happened. The thermal radiation plummeted. At…

Some of the more recent dramatic disasters in world-wide markets have occurred, not because people panicked or an election did not go someone's way, but because financial institutions have taken to hiring physicists who wrote papers on predicting chaos. If non-linear is just linear in really small steps, then predicting and controlling nonlinearity is manageable. But those extreme chaotic events, the "dragon kings", have not obeyed numerical models yet. An upcoming paper in Physical Review Letters seeks to tame that savage chaotic breast again, with a simple model of chaos predicting that it…

Plasmas are a soup of charged particles in an electric field. While most commonly a part of lightning bolts and stars, the use of high voltage equipment has more practically meant very small plasmas can be used to manipulate fluid flows. Plasma actuators have advanced the promise of controlling flows in new ways that increase lift, reduce drag and improve aerodynamic efficiencies, which may lead to safer, more efficient and more quiet land and air vehicles in the near future. Unlike other flow control devices, plasma actuator geometries can be easily modified. Enter the serpentine shape,…

It seems nowadays that makers (1) like to carry spare electronic parts around in a mint tin. Maybe I’m just Macgyver-old-school and prefer the challenge of getting along with just duct tape and a Leatherman Juice (OK, it is indeed an upgrade from Angus' Swiss Army Knife). Source) Anyway, I created my own electronics survival kit out of a zinc tablets box: Later on when I found a wooden cork art jewelry box at Goodwill for .50 USD, I tore the guts out of it so I could make a jewelry box electronics survival kit. Here’s a similar box so you can get an Idea of what it looked…

You can think of a capacitor somewhat like a rechargeable battery. It is able to store energy temporarily except that a rechargeable battery will last much, much longer than a capacitor. The simplest capacitor is two conducting plates with a non-conducting material such as paper sandwiched between them. You can make your own capacitor using aluminum foil and a book. Parts Needed: Aluminum foil from your kitchen A book with very thin pages (I used my copy of Engineering Fundamentals) 555 Timer IC (I used a KIA555p, but the NE555 will do just fine) Snap Circuit Parts needed: 1Base…

A tiny Micro-Electro-Mechanical System (MEMS) accelerometer used in smart phones to adjust the orientation of the screen could serve to create a real-time urban seismic network and increase the amount of strong motion data collected during a large earthquake, according to a new paper in the Bulletin of the Seismological Society of America. Since the 1990s, (MEMS accelerometers have been measure the rate of acceleration of ground motion and vibration of cars, buildings and installations. They revolutionized the automotive airbag industry and are found in many devices used daily, including…

An ordinary No. 2 pencil contains graphite (from the Greek γράφω, graphō which means "to write" or "to draw").  Graphite conducts electricity and you can use your pencil and a piece of paper to draw your own potentiometer then experiment with it using the 555 test circuit. Parts needed for pencil and paper potentiometer: No. 2 pencil Blank white 8 ½ X 11 sheet of printer paper Clear adhesive tape such as Scotch tape (optional) On the printer paper, draw a 1 cm X 20 cm rectangle and fill it in as completely and darkly as you can—the more graphite you use on the…

In my previous article, we took a look at one of the signals generated by the 555 test circuit where the output pin (pin 3) is connected to ground (-) which is a simple series of very brief pulses. This series of pulses can be used to generate a tone that can be used as an alarm or can be adjusted with a fair amount of precision such that it can be used to tune a musical instrument. I also touched upon the concept of On-Off Keying (OOK) a method of digital modulation used in optical communication such as IrDA.  Next, we’ll take a look at a signal that can be generated by the 555 test…

In previous articles, we've used the 555 test circuit as a hot liquid level indicator for the vision impaired and a cable tester as examples of some of the things that can be used as inputs to the 555 test circuit. In this article, we’ll take a look at one of the output signals that can be generated by the 555 test circuit.  In the above designs the output pin (pin 3) is connected to ground (-). The tone generated with pin 3 to ground is generally useful for qualitative analysis—that is, when a precise measurement isn’t necessary. In the case of the hot liquid level indicator, a…