1. Using a Microscope Question Student Name Date
Can a microscope be used to estimate the size of small objects?

2. Hypothesis
If you can estimate the number of objects that could fit across a microscope’s field of view, then you can estimate the size of the object.

3. Materials
Compound mic. • Clear ruler
Slide with “e”

4. Procedures
1. The diameter of the field of view at low power, (40X) is ______________ (include the units, eg. mm).
5 mm
2. The diameter of the field of view at medium power, (100X) is ______________ (include the units, eg. mm).
2 mm
3. The ratio of high power to low power is:
400/40 = _________. 10
4. The field of view at high power, therefore, is 1/10th of low power, or 5/10 =
0.5 mm

5. Procedures cont’d
Use the prepared slides of the letter e. Place it on the stage right side up. Use low power.
5. The number of “e’s” that could fit across the field of view at low power is ____________.
6. How does the “e” appear when you look through the eyepiece? _______________________________________
7. Try moving the slide to your right. Which way does the “e” appear to move when viewed through the eyepiece? ____
8. Try moving the slide up. Which way does the “e” appear to move? __________________
9. Why is there a difference? _______________________

6. Procedures cont’d
5. Use the prepared slides of the letter e. Place it on the stage right side up. Use low power.
6. The number of “e’s” that fit across the field of view at low power is ____________. 3
7. How does the “e” appear when you look through the eyepiece? _______________________________________
Larger, upside down
8. Try moving the slide to your right. Which way does the “e” appear to move when viewed through the eyepiece? ____
left
9. Try moving the slide up. Which way does the “e” appear to move? __________________
down
10. Why is there a difference? _______________________
The lenses invert the images.

7. Analysis p. 9
Record your answers to a,b,e, and f (p. 9), using full sentences and indicating the question in your answer.

8. Analysis p. 9
a. The coarse-adjustment know should not be used with the higher powered lenses because… ____________________
It may lift the stage into the lenses, cracking them.
b. As you move from low to high magnification… _______
The diameter of the field of view gets smaller/decreases.
e. For scanning several objects, …____________________
a low power would be better because it gives a larger field of view.
f. The cell can’t be seen when you move to higher power because…______________
i) It is no longer in the field of view.
ii) A solution is to first centre the cell in the field of view before going to higher power.

9. Conclusion
Was your Hypothesis supported, ie. Can you estimate the size of small objects if you know the field of view? How?
Count the number of the objects you can see across the field of view. Divide this number into the field of view, to find the actual size of the small object.
Eg: if the F.O.V is 5 mm, and you can see 3 “e’s”, then the size = 5/3, which = 1.7 mm