EXERCISE 18 



Problem. What does looking through the microscope do to the appearance of an object ? 



What to use. Compound microscope ; slide ; cover slip ; piece of printed paper with very small type. 



What to do. Place a drop of water on the slide ; immerse paper in the water ; place cover slip over 

 paper, focus under low-power objective. Keep both eyes open ; draw what you see. Center dot of an 

 " i " in the field, using the low power ; then turn to high power ; focus carefully ; draw. 



Record. Make an outline drawing exactly the size seen. In order to help you properly to gauge 

 the size of the letter, place a ruler on the table alongside of the base of the microscope. Try to focus 

 and examine the letter with both eyes open. Keep comparing the size of the field and the dot or letter 

 with the ruler. After the drawing is made, make a scale by measuring off the length of the letter used 

 on the slide. Note how many times the letter seems to have been enlarged when viewed through low 

 power ; through high power. Find out what the power of the two lenses is supposed to be after your 

 calculation is finished and recorded. 



Special exercise. Look up the history of the microscope and report in class. 



Questions. 1. What happens to the image when the object (slide) is moved to the right? 



2. What does the lens system do to the appearance of the object (image) besides enlarging it ? 



3. What are some important uses of the microscope ? 



4. What important social or economic changes have resulted from perfection of the microscope ? 



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