Microscope Calculations – Practice Questions
Using the formulas you have just learned, complete each of the following questions.
1. A microscope has an eyepiece lens with a power of 5X. The objective lens being used has a power of 10X.
Total magnification =
2. A microscope has an eyepiece lens with a power of 15X. The objective lens being used has a power of 40X
Total magnification =
3. A microscope has an eyepiece lens with a power of 10X. The objective lens being used has a power of 10X.
Total magnification =
4. Sue observes a clear plastic, millimeter ruler under low power of her microscope. She sees three divisions
of the ruler. What would be the field diameter of Sue’s microscope on low power? (in micrometers ('µm')
5.
Convert each of the following to micrometers (µm).
a)
3.5mm
b)
4.0mm
c)
1.5 cm
d)
0.5 cm
6. The following information is for a microscope which has an eyepiece lens (ocular lens) with a power of
10X:
Objective Lens
Low
medium
High
Power
4X
10X
40X
Field Diameter
3500 µm
?
?
Using the information provided above, calculate the field diameter for medium and high power.
The field of view is measured to be 3.5mm answer the following questions from 7-13
7. You observe that an object stretches across ¾ of the low power field. What is its approximate length?
8. If five cells fit across the high power field, what is their average length?
9. A cell is observed to stretch half way across the high power field. How long is the cell?
10. 15 cells are observed across the centre of the high power field. How long is each cell?
11. Many ponds often have a green scum on the surface. This scum is a tangled mass of stringy algae
filaments. Looking at a filament under high power shows four cells arranged end to end across the field of
view.
a.
What is the diameter of your high power field of view in micrometers?
b.
How long is each cell approximately?
12. Given the following information, estimate the approximate actual size of the organisms in each case in
micrometers. Round your answers to a convenient number. (they are only estimations).
a.
b.
c.
d.
e.
f.
g.
h.
A bug stretches ½ way across the low power field.
A cell stretches ¼ way across the medium power field
Twenty cells fit across the high power field
Fifteen plant cells stretch across the medium power field
A bug stretches 2/3 way across the medium power field
An insect stretches ¾ way across the high power field.
Five microbugs fit across the low power field.
Half a worm fits across the low power field.