1. Making Measurements with a Light Microscope

2. Metric Conversions 1 mm = 1000 μm 1 μm = 1/1000 mm

3. Instructions

4. Step 1 Place a transparent metric ruler under the low power (LP) objective (10X) of a microscope.

5. 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

6. Step 3 Convert this measurement to micrometers (μm) by using the following equation: d (LP) = 1.2 X 1000 = 1200 μm

7. 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

8. 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

9. Step 5 Width Length

10. Practice Problems

11. Practice Problem #1 Width of Red Fiber Width of White Fiber Couch Fibers 100X

12. Practice Problem #2 Height Water Flea 100X

13. Practice Problem #3 Paramecia 100X Width Length