Applied Physics

Arc discharges are common in welding and lightning storms but what about about in altered gravity conditions?

How often does that really come up? Not often, unless we ever send manned missions into space again, and it may be relevant in the design of ion thrusters used for spacecraft propulsion so let's do some science.

In a previous article I demonstrated how to build a conductivity tester out of Snap Circuits for your Science Play and Research kit.

You can use the same circuit with a small modification to build a simple magnetic stirrer. You can also further modify the circuit to make a reversible motor driver. Reversible motor drivers are often used in robotics to drive the robot forward or reverse, turn it right or left, to raise or lower a robotic arm, to open and close a robotic gripper, and so on.

Many owl species have developed specialized plumage to effectively eliminate the aerodynamic noise from their wings, allowing them to hunt and capture their prey in silence.  And owls are vicious. Imagine the Go Pro footage you would get if you stuck one of those on an owl for the evening.

A research group working to solve the mystery of exactly how owls achieve this acoustic stealth presented their findings at the American Physical Society's (APS) Division of Fluid Dynamics meeting over the weekend in Pittsburgh and hope their work on "silent owl technology" will help the design of aircraft, wind turbines, and submarines. 

If you have ever wondered about why you can tap a newly opened beer bottle and its suds will foam out and go all over the place, researchers from Carlos III University and Universite Pierre et Marie Curie, Institut Jean le Rond d'Alembert have provided some insight - by exploring the phenomenon of cavitation. 

Cavitation, a phenomenon relevant to such common engineering concerns as erosion of ship propellers, is the mechanism by which bubbles appear in a liquid such as beer after an impact, said Javier Rodriguez-Rodriguez, the lead researcher from Carlos III University.

A normally fragile quantum state has been shown to survive at room temperature for a world record 39 minutes, overcoming a key barrier towards building ultrafast quantum computers.

In conventional computers data is stored as a string of 1s and 0s. In the experiment quantum bits of information, 'qubits', were put into a 'superposition' state in which they can be both 1s and 0 at the same time – enabling them to perform multiple calculations simultaneously. 

Whistling kettles have been around for over a hundred years but science behind the mechanism of this siren sound, portent of delicious tea and cocoa (and heretical instant coffee) has never been fully described scientifically.

Ask an engineer or a physicist and you just get some hand-waving about the vibrations made by the build-up of steam escaping through two metal spout plates - everybody knows that, we whistle with our mouths too.

Patients may soon be able to get a bionic pick-me-up without undergoing the pain and lengthy recovery of surgery - an exoskeleton to support people who, through age or injury, are limited in their movement.

Anyone who has watched water exit a toilet bowl has learned something about fluid dynamics. But you can learn a thing or two by watching the pee that goes into it also.

Boring physicists apply the equations of fluid motion to boring thing like a flag in the wind or river currents, the American Physical Society Division of Fluid Dynamics (DFD) meeting in Pittsburgh will make things a little more practical for home research.

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.

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 80 degrees it looked blue, as if it could be 60 degrees, and at 85 it looked even colder. Moreover, the effect was reversible and repeatable, many times over.