When you magnify something under a microscope, you see it larger than it is really. Low power lenses usually magnify an object 40 times its natural size, medium power lenses magnify about 100 times and high power lenses magnify about 400 times. Most students feel that when you magnify something that is tiny, that you just get a bigger “tiny”.

You need 3 (maybe 5) circular pieces of graph paper that are 20 centimeters in diameter. You need a human hair. You need a microscope.

PROCEDURE:

1. Make a wet mount of a human hair. Length does not matter as long as it is longer than it is wide. (Hard to not meet that requirement).

2. Look at the hair under low power. Try to the best of your ability to record what you see, draw the hair onto the graph paper. Be very careful to reproduce the width of the hair the way that it looks in the field of view.

3. Without looking in the microscope, draw what the hair would like at medium power. Remember, medium power magnifies the width of the hair 100 times, but the low power already magnified the hair 40 times.
What must you do mathematically before you start?
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4. Now look at the hair under medium power. Does your drawing resemble the size of the hair in the field of view?

5. Again, without looking in the microscope, draw the hair at high power.
Remember, high power magnifies about 400 times. Count your boxes carefully.

6. Look at the hair under high power. Does your drawing resemble what you see in the field of view?

ENRICHMENT I:

7. DRAW THIS ONTO YOUR FOURTH SHEET OF GRAPH PAPER.
DON’T DRAW IT THE SIZE THAT YOU SEE HERE. DRAW IT AT “MEDIUM POWER”!

8. DRAW ANY PART OF CHARLIE BROWN THAT YOU WANT. BUT MAKE HIM “HIGH POWER”! A MILLIMETER RULER MIGHT BE HELPFUL.

ENRICHMENT II:

9. RETURN TO YOUR LOW POWER DRAWING OF THE HUMAN HAIR.
HOW WIDE IS THE HAIR? CLUE: THE DIAMETER OF THE FIELD OF VISION IS 5mm.

10. AFTER YOU DETERMINE HOW WIDE THE HAIR IS IN MILLIMETERS, TELL ITS WIDTH IN MICROMETERS AND NANOMETERS.