Applied Physics

Occasionally I’ll come across a web page that shows you how to make an infrared (IR) filter for your iPhone (in my case the iPod Touch) out of an old floppy disk. I had an old floppy disk so I decided to see if it would actually work. The process is actually fairly simple: take apart a floppy disk, cut out enough of the disk (the Mylar and iron oxide recording medium) to cover camera lens, tape the piece of floppy disk over the lens, point your camera, and shoot your picture.

I actually did have an old floppy disk that I could use for this experiment:

Silicon has been very good to us. It has given us Angry Birds and virtual protests we can participate in from the comfort of our home, but it may be time to enter the Age of the Biological Computer.

Writing in the journal Materials Today,researchers reveal details of logic units built using living slime molds, which might act as the building blocks for computing devices and sensors.


In honor of the upcoming National Robotics Week (April 5-13, 2014), I’ve created “CockroachBot” based on my Snap Circuits programmable robot I designed for last year’s robotics week. CockroachBot will try to run away when it detects a particular level of light falling on its light dependent resistor. I designed CockroachBot to be easy to build completely out of Snap Circuits parts and easy to program to inspire folks from seven to centenarian to get interested in robotics.

Revelations of the extent of American government surveillance into the private lives of both the American public and foreign leaders worldwide has shone a spotlight on the lack of security in digital communications.

Even today's encrypted data is vulnerable but physics may come to the rescue, according to a Nature article by Artur Ekert and Renato Renner ("The ultimate physical limits of privacy", doi:10.1038/nature13132).


Our bones are a matrix of minerals and other substances, including living cells, though most people don't think of them that way and assume bones are 'natural' —  but nature can be coaxed to do all kinds of things.

MIT engineers have coaxed bacterial cells to produce biofilms that can incorporate nonliving materials, such as gold nanoparticles and quantum dots. These "living materials" combine the advantages of live cells, which respond to their environment, produce complex biological molecules, and span multiple length scales, with the benefits of nonliving materials, but they add functions we don't usually associate with biology.

Self-assembling materials


Collectors,museums and art dealers face a lot of problems determining origin, authenticity and discovery of forgery of artwork. Experts are easily fooled - but science, not so much.

They get help through the application of modern, non-destructive, "hi-tech" techniques.  Spectroscopy is a technique that has been useful in the fight against art fraud because it can determine chemical composition of pigments and binders, which is essential information in the hands of an art specialist in revealing fakes. As described in a recent paper, "…according to the FBI, the value of art fraud, forgery and theft is up to $6 billion per year, which makes it the third most lucrative crime in the world after drug trafficking and the illegal weapons trade." 


There’s a popular YouTube video featuring mathematician Edward Frenkel where he describes how the NSA hacked our emails. It is a backdoor into the National Institute of Standards and Technology public key encryption standards.

I’ll borrow an analogy for a simplified description of how public key encryption works from Simon Singh. Imagine a sturdy metal box that can be locked shut with a padlock.

By now, almost everyone understands computers and that current technologies for writing, storing, and reading information are either charge-based or spin-based.

Spin-based devices operate on the principle that in materials like iron, electron spins generate magnetism and the position of the north and south pole of the magnet can be used to store the zeros and ones. This technology is behind both magnetic stripe cards and terabyte computer hard disks. Since these devices are based on spin, they are more robust against charge perturbations but the drawback is that in order to reverse the north and south poles of the magnet, i.e., flip the zero to one or vice versa, the magnetic bit has to be coupled to an electro-magnet or to another permanent magnet.


In my previous article DC Versus AC I discussed how a diode can be used as a rectifier to convert alternating current (AC) into direct current (DC) because the diode allows current to flow in one direction, but not the other.

The diode is the simplest semiconductor electronic component, but the physics of how they work is perhaps somewhat complicated. There are many resources available on the web such as the Edison Tech Center semiconductor resource page.

New battery management technology could boost Li-ion capacity by 40%, quadruple recharging cycles

Long-life laptop battery the tech industry doesn’t want you to have ?

Fed up with the dwindling battery life of his BlackBerry Bold 9000, Carleton University chemistry student Tim Sherstyuk took a straightforward problem to his electrical engineer dad, Nick: Could the two of them come up with the technology to make a standard lithium-ion battery last longer?
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