How Does a Transistor Work?

How does a transistor work? Our lives depend on this device. When I mentioned to people that I was doing a video on transistors, they would say "as in a transistor radio?" Yes! That's exactly what I mean, but it goes so much deeper than that. After the transistor was invented in 1947 one of the first available consumer technologies it was applied to was radios, so they could be made portable and higher quality. Hence the line in 'Brown-eyed Girl' - "going down to the old mine with a transistor radio."

But more important to our lives today, the transistor made possible the microcomputer revolution, and hence the Internet, and also TVs, mobile phones, fancy washing machines, dishwashers, calculators, satellites, projectors etc. etc. A transistor is based on semiconductor material, usually silicon, which is 'doped' with impurities to carefully change its electrical properties. These n and p-type semiconductors are then put together in different configurations to achieve a desired electrical result. And in the case of the transistor, this is to make a tiny electrical switch. These switches are then connected together to perform computations, store information, and basically make everything electrical work intelligently.

Infinite Solutions: How to Recharge Batteries

The right kind of batteries are never around when you need them. I'm Mark Erickson, and this is Infinite Solutions: Home Edition. In this episode, I'll show you how to recharge dead batteries using other types of batteries that still carry a charge.

OutRun Augmented Reality

Guy takes a cabinet from the 80's arcade game OutRun, turns it into something that can drive. But that's not all. Webcams, a computer, and special software look while you drive and convert real life roads into the game 80's graphic style!

Making The World's Smallest Movie

How did IBM researchers move all those atoms to make the world's smallest movie? This short behind-the-scenes documentary takes you inside the lab. Meet the scientists, see how they made a movie with atoms, and find out more about their research in the field of atomic memory and data storage. See the world's smallest movie at Learn more about atomic memory, data storage and big data at

A Boy & His Atom: World's Smallest Movie

You're about to see the movie that holds the Guinness World Records record for the World's Smallest Stop-Motion Film (see how it was made at The ability to move single atoms the smallest particles of any element in the universe is crucial to IBM's research in the field of atomic memory. But even nanophysicists need to have a little fun. In that spirit, IBM researchers used a scanning tunneling microscope to move thousands of carbon monoxide molecules (two atoms stacked on top of each other), all in pursuit of making a movie so small it can be seen only when you magnify it 100 million times. A movie made with atoms.

BBC: How to Make a Rocket

Jem witnesses the awesome power of rockets with the Bloodhound land speed record project.

HD clip from BBC 1 science series, Bang Goes the Theory.

Stop Motion Animation with 500 Smartphones

Video for Korean smartphone maker Pantech. This Matrix inspired video was created by building a 'Vega city' using hundreds of Vega No 6 smartphones, requiring three weeks of preparation to create 1,600 paper characters which then took 170 hours stop motion shooting to animate.

Numberphile: Safe Cracking

A chat about some of the ways legendary physicist Richard Feynman cracked safes (filing cabinets) at Los Alamos during the Manhattan Project.

Discussed by Professor Roger Bowley.

Magnetic Putty Time Lapse

Magnetic putty time lapse as it absorbs a rare-earth magnet. Taken over 1.5 hours at 3fps, played back at 24fps. The magnetic putty will eventually arrange itself so that the outer surface is as evenly distributed around the magnet as possible.

Ferromagnetic particles in the putty are strongly attracted to the magnet and very slowly engulf the surface of the magnet. The magnet shown in the picture is a strong neodymium iron boron magnet. It's a very powerful magnet for its size and could erase magnetic stripes found in credit cards and damage electronics!

The putty looks and feels like regular silly putty, but the difference lies in the fact that it has been infused with millions of micron-sized ferrous particles (most often iron oxide powder). The magnetic putty is not actually magnetic by itself, since the infused particles are made of iron powder.

The presence of the strong neodymium iron boron magnet (the silver cube in the video) magnetizes the ferromagnetic particles in the putty. When this happens, the ferrous particles align with each other and this alignment generates north and south magnetic poles, making the putty into a temporary magnet. Once magnetized, the putty will remain magnetized even after the rare-earth magnet has been removed from the putty. This effect persists for a few hours until thermal agitation shakes the particles and they lose their alignment.

Song is Blue Circles by unreal_dm licensed under Creative Commons Attribution

Here is a picture of what the putty looked like after a long time had elapsed

Introducing Google Nose

We're excited to announce our newest addition to Search: Google Nose. What do wet dogs smell like? Google Nose! How about victory? Google Nose! Try searching on Google for "wet dog" and explore other smells that people sniffed for, or visit to learn more. Happy smelling!