Making Measurements with a Light Microscope

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Making Measurements with a Light Microscope
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Metric Conversions

• 1 mm 1000 µm
• 1 µm 1/1000 mm

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Instructions
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Step 1

• Place a transparent metric ruler under the low
  power (LP) objective (10X) of a microscope.

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Step 2

• Focus the microscope on the scale of the ruler,
  and measure the diameter of the field of vision
  in millimeters (mm).

FOV (LP) 1.2 mm
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Step 3

• Convert this measurement to micrometers (µm) by
  using the following equation

d (LP) 1.2 X 1000 1200 µm
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Step 4

• Calculate the diameter in µm of the field of
  vision under high power (HP) using the following
  formula

d (HP) (1200 X 10)/40 300 µm
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Step 5

• To estimate the size of an object seen with a
  microscope under low power, first estimate what
  fraction of the diameter of the field of vision
  that the object occupies (LP). Then multiply the
  LP diameter you calculated in micrometers (step
  3) by that fraction.

Size (µm) fraction X 1200
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Step 5

• Width
• Length

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PracticeProblems
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Practice Problem 1
Couch Fibers

• Width of Red Fiber
• Width of White Fiber

100X
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Practice Problem 2
Water Flea

• Height

100X
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Practice Problem 3
Paramecia

• Width
• Length

100X
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