YouTube // PhysicsMadeFun
YouTube // PhysicsMadeFun

How Do LEDs Work?

YouTube // PhysicsMadeFun
YouTube // PhysicsMadeFun

I've watched lightbulbs change a lot in the past decades, and with each technology change I've had to re-learn how they work. Incandescent bulbs were everywhere when I was little, and some had already been burning for decades. I understood how those worked; we played around with filaments in school. Then along came compact fluorescent (CFL) bulbs, and I learned how those worked. Now, I'm slowly installing LED-powered bulbs. I'm surrounded by LEDs, both as indicator lights and in my TV, computer monitor, phone, and pretty much every other gadget. But how do they work? And why do some LED lightbulbs have huge heat-sinks on them?

This two-minute video from Physics Made Fun gives a very nice overview, breezing through the subject and even explaining why LEDs have different colors. Behold:

If you want a much longer, slower presentation, check out this video from the Edison Technology Center. Around 3:30, this video shows how OLED backlights are built.

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Mark Ralston, AFP/Getty Images
How a Hairdresser Found a Way to Fight Oil Spills With Hair Clippings
Mark Ralston, AFP/Getty Images
Mark Ralston, AFP/Getty Images

The Exxon Valdez oil tanker made global news in 1989 when it dumped millions of gallons of crude oil into the waters off Alaska's coast. As experts were figuring out the best ways to handle the ecological disaster, a hairdresser from Alabama named Phil McCroy was tinkering with ideas of his own. His solution, a stocking stuffed with hair clippings, was an early version of a clean-up method that's used at real oil spill sites today, according to Vox.

Hair booms are sock-like tubes stuffed with recycled hair, fur, and wool clippings. Hair naturally soaks up oil; most of the time it's sebum, an oil secreted from our sebaceous glands, but it will attract crude oil as well. When hair booms are dragged through waters slicked with oil, they sop up all of that pollution in a way that's gentle on the environment.

The same properties that make hair a great clean-up tool at spills are also what make animals vulnerable. Marine life that depends on clean fur to stay warm can die if their coats are stained with oil that's hard to wash off. Footage of an otter covered in oil was actually what inspired Phil McCroy to come up with his hair-based invention.

Check out the full story from Vox in the video below.

[h/t Vox]

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iStock
This Waterless Toilet Made of Mushrooms Could Be Key for Refugee Needs
iStock
iStock

In many parts of the world, toilets remain out of reach. An estimated one in three people in the world don't have access to a toilet, and one in nine people don't have access to safe water (in large part because of that lack of toilets). A group of students from the University of British Columbia have come up with a new way to give people without plumbing clean, safe places to do their business, and according to Co.Design the key is mushrooms.

The MYCOmmunity Toilet, which just won the 2018 Biodesign Challenge, is a portable toilet kit designed for refugee camps that uses a mycelium (a mushroom product) tank to eventually turn human waste into compost. Everything needed to set up the toilet is packed into one kit, which users can set up into a small, sit-down toilet with a traditional seat and a tank for waste. The appliance is designed to fit into a refugee tent and serve a family of six for up to a month.

The toilet separates solid and liquid waste for separate treatment. Enzyme capsules can be used to neutralize the smell of urine and start the decomposition, and poop can be covered in sawdust or other material to tamp down odors and rev up the composting process. After the month is up and the tank is full, the whole thing can be buried, and the mushroom spores will speed along the process of turning it into compost. The kit comes with seeds that can be planted on top of the buried toilet, turning the waste into new growth. (Biosolids have been used to fertilize crops for thousands of years.)

The University of British Columbia students—led by Joseph Dahmen, an assistant professor in the architecture school, and Steven Hallam, a professor in the department of microbiology and immunology—competed against 20 other design teams at the 2018 Biodesign Summit at the Museum of Modern Art in New York City in June, taking home first prize. They hope to further refine the prototype in the future, and according to Co.Design, test it out at local music festivals, which, with their outdoor venues and high volume of drunk pee-ers, are the perfect venue to stress test waterless toilet technology.

[h/t Co.Design]

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