Download D Unit 1 Videoscript

D
Unit 1 Videoscript
What is light?
Have you ever wondered what makes flowers pink and leaves green? Have you ever
seen trees reflected in a pool of water? Or a rainbow after a storm? If so, you’ve already
seen some of the properties of light, and light can do many things.
Most light we see is what we call white light. It does not seem to have any color, but
that can be deceiving. White light is actually made up of many different colors of light
together. This is called the visible light spectrum. You can see the visible light spectrum for
yourself by using a prism.
When sunlight shines through a prism, you can see that the white light is actually a
combination of many colors: red, orange, yellow, green, blue, indigo, and violet. Light
travels in waves. Each color has its own wavelength and is bent at a different degree as it
passes through the prism. Violet is bent the most and red is bent the least. The different
degrees of bending allow the spectrum to spread out and make the colors visible. We call
the bending of light refraction.
Another example of refraction occurs when we put a pencil in a glass of water. Light
waves travel faster in air than in water. As light waves pass from the air to the water, they
are bent. This creates an optical illusion that causes the pencil to appear bent.
Have you ever seen a rainbow after a storm? That is also refraction. The sunlight is
slowed down by water droplets in the air, and is refracted, making a rainbow. Even though
light slows down when it travels through an object, light speed is very fast. Light is so fast
that it could travel all the way around the world more than seven times in one second.
Sometimes light is reflected. When light is reflected, it bounces. When you look in a
pool of water and see the images of clouds or trees, you are seeing the reflection of light. It
bounces off the water and back to your eyes. You probably see light reflected almost every
day. Have you ever seen yourself in a mirror? When you look in a mirror, light bounces
back to your eyes. That’s why you can see your image, or reflection.
Absorption is another property of light. Most objects are what we call opaque, which
means light cannot pass through them. Things like desks, pencils, and even oranges are
opaque. When light strikes these objects, some of the light is absorbed, or taken in, and
some of the light is reflected. If the object appears orange, then it’s the orange light that
is reflected, and all the other colors of the spectrum are absorbed. Look at the leaves on
this tree. The leaves are green because every color except green has been absorbed. So
next time you see a sunbeam, pretty color, or a rainbow, you’ll know there’s much more to
light than meets the eye.
Copyright © 2008 Pearson Education, Inc. All rights reserved. Permission granted to reproduce for classroom use.