Two Perspectives On James Clerk Maxwell And His Equations

We are unabashed fans of [The History Guy’s] YouTube channel, although his history videos aren’t always about technology, and even when they are, they don’t always dig into the depths that we’d like to see. That’s understandable since the channel is a general interest channel. However, for this piece on James Clerk Maxwell, he brought in [Arvin Ash] to handle the science side. While [The History Guy] talked about Maxwell’s life and contributions, [Arvin] has a complementary video covering the math behind the equations. You can see both videos below.

Of course, if you’ve done electronics for long, you probably know at least something about Maxwell’s equations. They unified electricity and magnetism and Einstein credited them with spurring one of his most famous theories.

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Table Held Up By Strings Teaches Physics

If you’ve never heard of a tensegrity structure, you should stop now and watch the video below. In it, [The Action Lab] shows a 3D printed table that is held up only with strings. We didn’t say suspended by strings but held up. Or so it appears. The model is from Thingiverse, but it is one of those things you have to see to believe.

The basic idea is pretty simple. Strings have a lot of tensile strength but collapse under the slightest compressive force. The arrangement of strings puts the force on the center string which is essentially hanging — the force is pulling the string down. The other three strings aren’t just for show, though, they keep the structure from tipping over in any one direction.

There are actually real-life examples of these kinds of structures. The video shows the Skylon at the Festival of Britain as one example and an Australian bridge. The video also makes the point that the human body uses tensegrity, since tendons are very similar to the strings in the model.

This would be a great experiment for a homeschooler or even kids cooped up in quarantine. The print itself doesn’t look very challenging, although the assembly might be a bit tricky.

This isn’t the first structure like this that we’ve seen. If the talk about tendons makes you think this might be useful in robotics, you’d be correct.

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Quantum Sensor Receives From 0 Hz To 1000 GHz

Although it isn’t that uncommon to have broadband radio coverage in a single device, going from 0 Hz to 1000 GHz with one antenna and receiver is a bit much. But not for the US Army it seems, because they’ve developed a quantum sensor that can cover that range.

The technology uses Rydberg atoms, which are atoms with a highly excited valence electron. They’ve been used for a variety of sensing applications before, such as reading the cosmic microwave background radiation. However, until the Army’s work there has been no quantitative analysis of using them for wide-spectrum communications.

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Compact Slayer Exciter For Your High Voltage Needs

Tesla coils are incredible pieces of hardware, but they can be tricky to build. Between the spark gap, capacitors, and finely tuned coils, it’s not exactly a beginners project. Luckily, there’s hope for anyone looking for a less complex way to shoot some sparks: the Slayer Exciter. This device can be thought of as the little cousin to the Tesla coil, and can be used for many of the same high voltage experiments while being far easier to assemble.

Now [Jay Bowles] is obviously no stranger to building his own Tesla coils, but since so many of his fans wanted to see his take on this less complex option, he recently built his own Slayer Exciter. After putting on a few of his own unique touches, the end result looks very promising. It might not be able to throw sparks as far as some of the other creations featured on his YouTube channel, but it’s still impressive for something so simple.

[Jay] uses two transistors in parallel for reliability
When we say simple, we mean it. Building a bare-bones Slayer Exciter takes only takes five components: the two coils, a transistor, a diode, and a resistor. For this build, power is provided by a trio of rechargeable 9 V batteries in the base of the unit which can be easily swapped out as needed.

In the video, [Jay] does a great job explaining and illustrating how this basic circuit creates exceptionally high frequency energy. In fact, the frequency is so high that the human ear can’t hear it; unfortunate news for fans of the Tesla coil’s characteristic buzz.

Generally speaking Slayer Exciters would have the same sort of vertical coils that you’d see used on a traditional Tesla coil, but in this case, [Jay] has swapped that out for a pancake coil held in the upper level of the device. This makes for a very compact unit that would be perfect for your desk, if it wasn’t for the fact that the arcs produced by this gadget are hot enough to instantly vaporize human skin. Just something to keep in mind.

We’ve seen Slayer builds in the past, but none as well designed as this one. Incidentally, if you’re wondering about the array of neon indicator lights that [Jay] uses to visualize the electrical field, we covered that project as well.

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Where Do You Get Your Neutrons? Neutron Sources For Nuclear Fusion, Science, Medicine, And Industry

All of us probably know what neutrons are, or have at least heard of them back in physics class. Yet these little bundles of quarks are much more than just filler inside an atom’s nucleus. In addition to being an essential part of making matter as stable as it (usually) is, free neutrons can be used in a variety of manners.

From breaking atoms apart (nuclear fission), to changing the composition of atoms by adding neutrons (transmutation), to the use of neutrons in detecting water and inspecting materials, neutrons are an essential tool in the sciences, as well as in medicine and industrial applications. This has meant a lot of development toward the goal of better neutron sources. While nuclear fission is an efficient way to get lots of neutrons, for most applications a more compact and less complicated approach is used, some of which use nuclear fusion instead.

In this article we’ll be taking a look at the many applications of neutron sources, and these neutron sources themselves.

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Drones Can Undertake Excavations Without Human Intervention

Researchers from Denmark’s Aarhus University have developed a method for autonomous drone scanning and measurement of terrains, allowing drones to independently navigate themselves over excavation grounds. The only human input is a starting location and the desired cliff face for scanning.

For researchers studying quarries, capturing data about gravel, walls, and other natural and man-made formations is important for understanding the properties of the terrain. Controlling the drones can be expensive though, since there’s considerable skill involved in manually flying the drone and keeping its camera steady and perpendicular to the wall it is capturing.

The process designed is a Gaussian model that predicts the wind encountered near the wall, estimating the strength based on the inputs it receives as it moves. It uses both nonlinear model predictive control (NMPC) and a PID controller in its feedback control system, which calculate the values to send to the drone’s motor controller. A long short-term memory (LSTM) model is used for calculating the predictions. It’s been successfully tested in a chalk quarry in Denmark and will continue to be tested as its algorithms are improved.

Getting a drone to hover and move between GPS waypoints is easy enough, but once they need to maneuver around obstacles it starts getting tricky. Research like this will be invaluable for developing systems that help drones navigate in areas where their human operators can’t reach.

[Thanks to Qes for the tip!]

The Legacy Of One Of Science’s Brightest Stars: Freeman Dyson

Of the many well-known names in science, few have been as reluctant to stick to one particular field as Freeman John Dyson. Born in the UK in 1923, he showed a great interest in mathematics and related fields even as a child. By the time he was 15 he had won a scholarship at Trinity College, in Cambridge, where he studied mathematics. Though the war forced him to work at the Air Force’s Operational Research Section (ORS), afterwards he would return to Trinity to get his BA in mathematics.

His subsequent career saw him teaching at universities in the UK and US, before eventually ending up at Cornell University, where he joined the Institute for Advanced Study at the invitation of its head, J. Robert Oppenheimer. Here he would meet up with such people as Richard Feynman with whom he would work on quantum electrodynamics.

Beyond mathematics and physics, Dyson would also express great interest in space exploration — with Dyson spheres being well-known — and genetics, both in the context of the first formation of life and in genetic manipulation to improve plants to deal with issues today. He also worked on the famous Project Orion, which used nuclear bombs for propulsion.

In this article we’ll take a look at these and other parts of Mr. Dyson’s legacy, as well as the influence of his works today.

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