Physical Science
Physical science is the study of the physical world around you. Learn about everything from electricity to magnetism in this section.
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I recently used chlorine bleach to clean the siding on my house, and I was amazed at how well it worked! What is bleach? How does it remove stains? Is the chlorine in bleach the same as the chlorine in drinking water or in swimming pools? Is chlorine safe to use?
By Yara Simón
Just how far can the human eye see? There's no exact formula to figuring it out, but we do have an idea.
I once saw this device shaped like a light bulb. It had a vertical support inside it, and on that support there were four vanes with four diamonds on the end. One side of the diamond was black and the other was white. I did a little research and found out that it was called a Crookes' radiometer -- how does it work?
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I have a thin piece of plastic mounted on the back window of my RV. It magnifies things so I can see better when I'm backing up. How can such a thin piece of plastic magnify things? A regular glass magnifying lens would have to be curved on both sides and much thicker.
Bullet size is measured in calibers, but how are wires and nails measured? Learn about bullet size and caliber in this article.
Many ads for new clocks advertise their ability to automatically synchronize themselves with the atomic clock in Boulder, Colorado. This atomic clock is more precise because it uses the frequencies of atoms as its resonator.
Chemical formulas provide a concise explanation for reactions. In this article, we explain the formula for the reaction in a smoke detector.
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When an airplane flies faster than the speed of sound, you hear a large booming sound. But how can something that seems so simple cause such a boom?
Radar is used to track storms, planes, and weapons and also to create topographic maps. Learn about radar, radar technology and Doppler shift.
Nuclear materials get used in many forms of nuclear medicine -- everything from PET scans to chemotherapy uses them. Learn how nuclear medicine works.
On the one hand, nuclear power offers a clean energy alternative that decreases fossil fuel dependence. On the other, it summons images of quake-ruptured Japanese power plants leaking radioactive water. What happens in reactors in good times and bad?
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The air we breathe contains 21 percent oxygen. Would we be better off breathing 100 percent oxygen?
Alfred Nobel revolutionized several industries with his invention of dynamite. Learn more about how dynamite works and its controversial history.
By Yara Simón
Just about everyone has seen a television show or movie in which a criminal suspect is questioned while detectives watch from behind a one-way mirror. How does a piece of glass manage to reflect light from one side while remaining clear on the other?
Rust is the common name for iron oxide, which is created when iron bonds with oxygen. In fact, pure iron is only rarely found in nature because it interacts with oxygen so easily.
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I recently bought a pair of mirrored sunglasses and they are already scratched. Isn't there a way to make them scratch-resistant?
They stick around long after death and compete with the likes of Dracula, Frankenstein's monster and the Wolfman as one of the great figures of classic horror movies. Are you brave enough to unravel the history of these real-life, tangible ghosts?
By Tom Harris
The human eye misses a lot -- enter the incredible world of the microscopic! Explore how a light microscope works.
If you want to see a hologram, you don't have to look much farther than your wallet. But the most impressive holograms are large scale and illuminated with lasers or displayed in a darkened room with carefully directed lighting. Learn how a hologram, light and your brain work together make clear, 3-D images.
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If the idea of being completely knocked out by a cocktail of drugs while doctors operate on you freaks you out, you're not the only one. But that's not what anesthesia is all about it - and it might scare you less if you understand how it works.
When the power goes out and is later restored, how do you know what time to set your clocks to? Have you ever wondered how time is regulated? Learn how scientists determine exact time.
About 90 percent of Americans consume some form of caffeine every day: It's our most popular drug by far. What's so special about this stimulant?
Helium balloons tend to fascinate adults and children alike (and it's not just the Donald Duck voice thing, though that is a big draw). Learn all about helium and why it floats!
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Nuclear radiation can be extremely beneficial or extremely harmful -- it all depends on how it's used. Learn what nuclear radiation is all about.
Whether the circle is as big as planet Mars or as small as a tennis ball, the ratio of its circumference divided by its diameter will always equal pi (3.14). But why?