MAGNIFICATION BY MICROSCOPE LENSES
Compound microscopes magnify small things and allow us to see more detail. This short activity will let you become familiar with the magnifying powers of a light microscope.
1. Place a prepared slide of salt crystals on the stage.
2. Turn the nosepiece until the low power objective (4x) is below the tube and above the opening in the stage.
3. Look through the eyepiece (ocular).
4. Focus. Use the coarse focus first and then the fine focus.
5. Estimate how many times larger the salt crystals are at low power than when you look at them with your eye:
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6. Use this formula to determine mathematically the magnification of the salt crystals at low power:
LOW POWER MAGNIFICATION X EYEPIECE MAGNIFICATION =
TOTAL MAGNIFICATION
(REMEMBER: LOW POWER IS 4X AND THE EYEPIECE IS 10X)
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7. Turn the nosepiece so that you are looking through the medium power lens.
DRAW a salt crystal that you see while using the medium power objective:
DRAW a salt crystal that you see at low power.
*ESTIMATE how much larger the salt crystal appears at 10x than 4x:
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*ESTIMATE how much larger the salt crystals appear at medium power than when you look at the crystals without a microscope:
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*Use the formula from direction #6 to determine the actual amount of magnification at medium power:
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8. If your microscope can rotate to see the salt crystals at high power, do that now.
*Use the formula from #6 to determine the actual amount of magnification at high power:
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NOTE TO TEACHER: Very small print can be used in place of salt crystals.
This may be preferable for beginning microscopists. For more advanced students, onion cells work well.