1. MICROSCOPE

2. Parts of the Microscope
Eyepiece
Coarse Adjustment
Fine Adjustment
Objectives (LP, HP)
Arm
Stage
Light source
Base
Diaphragm

3. FUNCTIONS – Magnifies image (10X)
Used for rough focus (use with low power)
Used for fine adjustments (use with high power)
Enlarges image (scanning 4x, low power 10x, high power 40x)
Used for carrying microscope
Platform for holding the slide
Can be a mirror or light bulb
Used for carrying the microscope
Adjusts the amount of light

4. To Find Total Magnification
How large is the cell in the diagram below?
Multiply the eyepiece and the objective lens to get the total magnification.
The greater the total magnification, the smaller the field of view (FOV) or area that you see. The lower the total magnification, the larger the field of view (FOV).

5. Calculate the total magnification
Eyepiece
Lens
Objective
Total
Magnification
a. 10x 4x
40x
b. 10x
10x
100x
c. 10x
400x

6. REVIEW QUESTIONS
With which combination of lenses would you be able to see the largest area of a specimen? Eyepiece & scanning(4x) (largest FOV) or eye & low power ( 10x) if scanning is not there
The smallest area? Eyepiece 10x & High power 40x (smallest FOV)
Which set of lenses would you use to locate a specimen on a slide? Eye & 4x(scanning) or 10x (low power)
Which set would you use to examine the details of a specimen? Eyepiece & 40x (high power)

7. HIGH POWER LOW POWER -How much can you see?
FIELD OF VIEW
-How much can you see?
In High Power we see 25% of the low power FOV (low power 100 x is 25% of high power 400x)
We see less of the specimen but we see more details of the specimen under high power
LOW POWER
HIGH POWER

8. More Review Questions:
1. After switching from high power to low power the area of the field of view will appear
a. larger and brighter
b. Smaller and brighter
c. larger and darker
d. smaller and darker
2. What should a student adjust if the field of view seems too dark?
________________________________
3. Is the field of vision smaller or larger under low
power? ______________________________________

9. Even more review questions:
4. To locate and observe a specimen under a slide, a student should begin by using what objective and what adjustment knob?
5. What adjustment knob should you use if you are using high power?
6. Why should a specimen be centered in the middle of the field of view when focusing under low power?

10. Electron Microscope
The limit of resolution restricts the usefulness of light microscopes for studying VERY small specimens such as
viruses.
• Electron microscopes use a stream of electrons to view these specimens.
• Electron microscopes have a limit of resolution more than 1000 times finer than light microscopes.

12. FIELD OF VIEW Low Power (100x) Find the diameter of the LP FOV
How do we find the FOV of a microscope?
Low Power (100x)
Find the diameter of the LP FOV
Use the clear metric ruler (mm side)
Be sure to line up the first mm mark with the left side of the field.
LP FOV = 1.5 mm

13. 1 mm = 1,000 µm
1 µm = 1/1000 mm or 0.001mm
The mm is too large to measure microscopic objects, so you need to use the micron (micrometer) µm
LP FOV = 1500µm

14. So how do we determine how big something is in the microscope?
Let’s see how it works:
So how do we determine how big something is in the microscope?
Use the following formula:
FOV
# of cells
(that can fit across diameter)
FOV = 2mm = .5mm
# of
cells
OR .5mm x 1000 =500 microns