Today’s Wonder of the Day was inspired by alexis. alexis Wonders, “why see stuff bending in the water when its not” Thanks for WONDERing with us, alexis!
Have you ever had a friend who told you a story so incredible that you just couldn't believe it unless you saw it with your own eyes? Even if it were your best friend whom you trusted, you might have trouble believing something you hadn't seen for yourself.
After all, the eyes can be trusted, right? The phrase "seeing is believing" is popular for a reason, isn't it? Or can your eyes deceive you from time to time?
If you've ever put a straw into a glass of clear water, then you know that your eyes can deceive you. Most people are intrigued the first time they notice that the water in the glass appears to bend the straw where it enters the water. What's going on here? Is it magic?
Nope! It's science. And this interesting phenomenon has everything to do with the physical properties of light.
If you know much about light, you know that it travels in a straight direction with incredible speed. Many people believe the speed of light is constant, but what we refer to as the speed of light only pertains to light that is traveling in a vacuum.
When light travels through other materials, such as water, it behaves differently. For example, when light encounters water, it bends and slows down. Scientists call this refraction.
If you want to envision how this happens, think about a time when you've gone swimming at a pool. As you run to jump into the pool, your body moves quickly through the air. As you walk through the water, though, you tend to lean forward as your body slows down. The water is simply harder to push out of the way than the air you were just running through.
So how does this apply to the straw in the glass of water? The portion of the straw above the water reflects light back to your eyes in a straight line. The portion underwater, however, reflects light that must pass through the water and is therefore refracted.
Your eyes assume the light is still traveling in a straight line and the fact that it is not causes the visual distortion you see as the straw appearing to be bent. The water doesn't actually bend the straw, but it does bend the rays of light reflecting off the straw.
The science of refraction has important uses in everyday life. Do you wear glasses or know someone who does? The lenses in eyeglasses take advantage of the principle of refraction to correct vision problems by adjusting where light is focused in your eyes. Refraction is also an important part of the science behind other types of optical equipment, such as binoculars, cameras, and telescopes!