Physical Science

Physical science is the study of the physical world around you. Learn about everything from electricity to magnetism in this section.

Topics to Explore

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How Does a Lie Detector (Polygraph) Work?

You may know a bit about polygraphs, but do you know which physical reactions it actually monitors?

Physical Science / Forensic Science

What is a decibel, and how is it measured?

The decibel scale measures sound based on human hearing, which makes it one of the most unusual scientific measurements. How are decibel calculated and what do they tell us about sound?

Physical Science / Acoustics

How does chlorine bleach work?

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?

Chemistry / Chemical Compounds

Why is carbon monoxide poisonous?

I have heard that carbon monoxide is extremely poisonous. Can you explain why?

Chemistry / Chemical Compounds

When I stand at the water's edge and look out over the ocean, how far away is the horizon?

When I stand at the water's edge and look out over the ocean, how far away is the horizon? Is there an equation to figure it out?

Physical Science / Optics

What is dioxin?

What is dioxin? There's a lot of discussion going on in my town about dioxin and its dangers.

Chemistry / Chemical Compounds

How does a Crookes' radiometer work?

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?

Physical Science / Nuclear Science

How does a Fresnel lens 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.

Physical Science / Optics

Can you explain the diameter measurements used in bullets, wire and nails?

Bullets, wires and nails are all measured with unusual measurement systems and units -- and they all show just how interesting measurement systems can be!

Physical Science / Forensic Science

What is an atomic clock and how does it work?

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.

Physical Science / Nuclear Science

How do you write the chemical reaction that takes place in a smoke detector?

Chemical formulas provide a concise explanation for reactions. In this article, we explain the formula for the reaction in a smoke detector.

Chemistry / Chemical Processes and Tests

What causes a sonic boom?

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?

Physical Science / Acoustics

What causes helium balloons to lose their lift after a day or two?

Scenario: A helium balloon is up against the ceiling one day, and the next day it's on the floor. Does the balloon fall because the helium leaks out, or because the helium molecules slow down due to decreased pressure?

Chemistry / Chemical Processes and Tests

How Anesthesia Works

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.

By Shanna Freeman Chemistry / Chemical Compounds

How Atomic Clocks Work

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.

By Douglas Dwyer Physical Science / Nuclear Science

How Caffeine Works

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?

By Marshall Brain, Charles W. Bryant & Matt Cunningham Chemistry / Chemical Compounds

How Helium Balloons Work

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!

By Marshall Brain Chemistry / Chemical Processes and Tests

How Lasers Work

Lasers are used in CD players, dental drills, eye surgery, and even tattoo removal. But what exactly is a laser? There are numerous types, but all lasers work basically the same way. Learn how they generate such concentrated beams of light.

By Matthew Weschler Physical Science / Optics