Making Measurements with a Light Microscope
Metric Conversions 1 mm = 1000 μm 1 μm = 1/1000 mm
Instructions
Step 1 Place a transparent metric ruler under the low power (LP) objective (10X) of a microscope.
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
Step 3 Convert this measurement to micrometers (μm) by using the following equation: d (LP) = 1.2 X 1000 = 1200 μm
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
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
Step 5 Width Length
Practice Problems
Practice Problem #1 Width of Red Fiber Width of White Fiber Couch Fibers 100X
Practice Problem #2 Height Water Flea 100X
Practice Problem #3 Paramecia 100X Width Length