1. HOW TO MEASURE MICROSCOPIC OBJECTS
A cluster of Escherichia coli bacteria magnified 10,000 times.

2. To put things in perspective,
We need to consider some microscopic subjects and their size. Most people will have heard of an Amoeba. The typical size of this microscopic animal is 0.8 mm ( 8/10 of a millimeter) long by 0.4mm (4/10 of a millimetre) wide: just about visible to the naked eye! Measured in microns, the creature is quite large microns by 400 microns. It is a good reference size to consider smaller life-forms and objects against.
Amoeba

3. Euglena ( protozoan)
Typically 130 x 50 microns - much smaller than our large amoeba. It uses a whip like tail called a flagellum to propel itself through water at the rate of 20 to 200 microns per second. Compare this speed to its own body-length and than consider this to the speed of a Paramecium, another protozoan

4. Paramecium (another protozoan)
"weighing-in" at 240 x 80 microns; the latter uses cilia (tiny hairs) to move through the water at 400 to 2000 microns per second.

5. Escherichia coli image is 8 micrometres wide.
Bacteria
Escherichia coli image is 8 micrometres wide.
much smaller than any of the other forms and cells discussed so far, are typically between 1 micron to 10 microns in length; the latter being the length of the rod-shaped bacteria. If you look at the millimeter scale on your ruler, you can try and visualize 1000 bacteria lined up in a chain between the two marks indicating a millimeter width... or maybe just 8 Euglena "nose-to-tail".

6. What is the length of one onion cell???
How would you figure that out??
Onion Cells under Low Power (100x)

7. Now could you tell me how large the cell is???

8. To do this it will first be necessary to find the diameter of the low power field of view (FOV)
PROCEDURE:
Use the clear metric ruler (mm side)
Be sure to line up the first mm mark with the left side of field

9. LP FOV = _____ mm
1.5

10. However, the mm is too large to measure microscopic objects, so you need to use the micrometer (micron) um
1 mm = 1,000 um
1 um = 1/1,000 mm or mm

11. Convert your LP FOV in mm to um
Use the metric sidewalk:
K H D M d c m x x u
When converting from mm to um, move the decimal point 3 places to the right
LP FOV = _______ um
1500

12. HIGH POWER ( )
400
Since you know the LP FOV, you just need to set up a proportion to calculate the HP FOV.
LP Mag
HP Mag
HP FOV is LP FOV
1/4

13. So just divide the LP FOV by 4:
1500 / 4 = 375
HP FOV = _______
375 um

14. GENERAL RULES FOR SWITCHING POWER:
If you know the LP FOV, ________ to get HP FOV
If you know the HP FOV, ________ to get LP FOV
divide
multiply

15. HP is 1/6 LP FOV for this microscope!
QUESTION:
If we switch microscopes and the new microscope has a HP magnification of 600X instead of 400X, how do you find the HP FOV? LP HP
100X
600X = =
1/6
HP is 1/6 LP FOV for this microscope!

16. Length of ameba = ________
Now you can measure microscopic objects in the HP FOV by comparing them to the diameter of the field.
1500
LP FOV DIAMETER = __________ um
1500 4
375
HP FOV DIAMETER = __________ um
FORMULA:
HP FOV Diameter = length of
# times object object
fits across
375 5
375 um
HP FOV = ________
75 um
Length of ameba = ________

18. BACTERIA

19. SPIDER

20. MOSQUITO (FALSE COLOR)

21. FLY FOOT

22. RED FIRE ANT

23. MICROBES

24. POLLEN

25. Snowflake

26. Another snowflake

27. FLEA

28. SEM images – 3-D
ANTARCTIC MITE (1500x)

29. Tip of a tatoo needle

30. Eyelash hair

31. Velcro hooks

32. Kitchen sponge with bacteria and fungus

33. Cat hair

34. Brown Recluse Spider

35. American Dog Tick
Larvae

36. Crab Spider

37. Roundworm (in dogs)

38. Cattle hookworm

39. Cat tongue papillae

40. Cichlid fish gills

41. E. coli on surface of human skin and hair follicle

42. Human nose hair with mucus, pollen grain (green) and dead skin cells

43. Human tooth with accumulation of bacterial plaque (smooth areas) and calcified tartar (rough areas) on enamel surface.

44. Head louse

45. Staphylococcus aureus colony
Staphylococcus aureus colony. MRSA strain (resistant to all penicillin-like antibiotics)

46. H1N1

47. Electron Photomicrographs supplied by:
Dennis Kunkel Microscopy, Inc

48. PRACTICE PROBLEMS

49. 1. How big is this Field of View in millimeters???
3.5 mm

50. 2. If the Field of View is 1.5 mm, what is the length of the paramecium in micrometers?

51. 3. What is the length of one of the cells below in millimeters
3. What is the length of one of the cells below in millimeters? ___________ In micrometers? ___________
.5 mm
500 um

52. THE END