Physical Science

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.

By Patrick J. Kiger

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?

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.

By Austin Henderson

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.

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?

By Austin Henderson

Radar is used to track storms, planes, and weapons and also to create topographic maps. Learn about radar, radar technology and Doppler shift.

By Marshall Brain

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.

By Tracy V. Wilson

Atom smashers tell us about the fundamental structure of matter, the forces holding it together and the origins of the universe. Discover how scientists use particle accelerators to break atoms apart to learn about the nature of reality.

By Craig Freudenrich, Ph.D.

I was watching an old movie today, and two kids (neighbors) were talking to each other using two tin cans and a string. Does that really work? If so, why does it work?

Some of the brightest minds in history have focused their intellects on the subject of light. Einstein even tried to imagine riding on a beam of light. We won't get that crazy, but we will shine a light on everything scientists have found so far.

By William Harris & Craig Freudenrich, Ph.D.

What makes sound a weapon? Review the basics of sound and discover exactly how the LRAD produces its "beam of sound." We'll also explore LRAD's hailing and warning abilities and other uses for sound.

By Tracy V. Wilson

If water is made up of hydrogen and oxygen, why can't we breathe underwater? It has to do with how molecules combine and how the human lung functions.

Ever wondered exactly what they "artificial flavors" in your candy are, and why no specific ingredients are listed? Find out in this article.

By HowStuffWorks.com Contributors & Yara Simón

NASA's Mars rovers are sending 3-D images to Earth, so we can see depth and texture on the Martian surface. And how do we see this depth and texture? 3-D glasses, of course! Check out how they work.

By Marshall Brain

Most of us have heard the talk about oysters and chocolate, and maybe you've read an article about the stimulating effects of ginseng. But garlic, licorice and cucumber? Learn about the history of aphrodisiacs and whether they've been proven to be effective.

By Lee Ann Obringer

An invisibility cloak seems perfectly believable in the magical world of Harry Potter, but in the real world, it's impossible, right? Not so fast.

By William Harris & Robert Lamb

Fusion reactors will use abundant sources of fuel, will not leak radiation above normal background levels, and will produce less radioactive waste than current fission reactors. Learn about this promising power source.

By Patrick J. Kiger & Craig C. Freudenrich

Learn what really goes on when a CSI "processes a crime scene" and get a real-world view of crime scene investigation from a primary scene responder with the Colorado Bureau of Investigation.

By Julia Layton

Electricity completely surrounds us whether you're charging your cell phone or watching the sky light up during a violent thunderstorm. For most of us, modern life would be impossible without it, and the natural world relies on it.

By Marshall Brain, William Harris & Robert Lamb

The thought of an autopsy usually provokes fear, apprehension or extreme anxiety in people. Cut through the mystery of this process and learn the details of the preparation, procedures and tools used to perform an autopsy.

By Robert Valdes & Patrick J. Kiger

Viagra is one of the best-known drugs of all time. Nearly every adult in America has heard of the drug and can tell you what it does. Find out how this high-profile medication works its magic.

By Marshall Brain & Katie Lambert

Crack cocaine, like many other illegal drugs, leads to addiction, death, increased crime rates and imprisonment. But this drug targets the inner city almost exclusively and possession or distribution of crack carries extremely harsh prison sentences.

By Stephanie Watson & Nathan Chandler