reflection

CD Spectrum

This experiment uses a computer CD or DVD. If you have ever looked closely at either a music or computer CD, you have probably noticed that they produce rainbows. If you hold the CD with the shiny side up and let light from a lamp reflect off of it, you will see a very nice rainbow of colors. If you are using a regular incandescent bulb, you will see all of the colors of the rainbow: Red, orange, yellow, green, blue, indigo, violet. If you use other kinds of bulbs, you may find some colors missing.

Bouncing Remotes

This experiment comes from spending too much time in hotel rooms as I travel. As I was packing for the trip home, I found a very useful technique for adjusting the television when I was not directly in front of it.

Minerals: Streak

To perform the streak test, you rub a specimen on a piece of unglazed porcelain tile. Go to your local hardware store, and look at the backs of their floor tiles. You want a tile that is made of porcelain, and the unglazed back should have a white color.

These tiles are very hard (hardness 6.5), and they have a rough surface. As you rub the mineral across that surface, it acts like a file, powdering up some of the mineral. The color of that powdered mineral is its streak color.

Minerals: Luster

At first, many people find luster a bit confusing. Luster is the way that an object reflects light, and although the different types of luster can be difficult to describe, your daily experience makes them easy to recognize. Once you understand luster, you will recognize the common lusters instantly.

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