1. Chapter 7 The Microscope

2. Learning Objectives By the end of this topic, you will be able to
Name the parts of the microscope and their functions.
Use the microscope to observe biological specimens
Know the difference between the light microscope and the electron microscope

3. Compound Microscopes
The microscopes used in our lab are called compound microscopes because they have two magnifying lens
The Eyepiece Lens is the lens that you look through.
The objective lens is the lens that is immediately above the specimen.

4. The Objective Lenses There are three objective lenses:
- the scanning lens with the 4X label
- the low power lens with the 10X label
- the high power lens with the 40X label

5. Parts of the Microscope

6. Parts of the Microscope
Function
Lenses
Magnification
Stage
To place the slide on
Clips
Hold the slide in place
Diaphragm
To control the amount of light
Coarse Focus Knob
To focus the image
Fine Focus Knob
To precisely focus the image
Light
To supply light to the object

7. Learning Check Label the parts of the Microscope

8. Magnification Magnification =
the magnifying power of the eyepiece lens x
the magnifying power of the objective lens.
Example:
Eyepiece lens = 10X
Objective lens = 4X
Total magnification = 10 x 4= 40X

9. Focusing The Image
The course focus knob allows for dramatic or large movement of the objective lens.
The fine focus knob allows for very slight movement of the objective lens.

10. The Stage and the Diaphragm
The stage has two metal clips to hold the microscope slide in place.
The diaphragm allows light to be focused onto the specimen through a hole in the stage.

11. ELECTRON MICROSCOPE

12. Electron Microscope Uses Electrons instead of light
Electrons have much lower wavelength than light
Resolution is much better
Magnification is much greater

13. Images from Electron Microscope
Platelet
Bacteria
Cytplasm

14. Learning Check What is the function of each of these parts of the Microscope?
Eyepiece Lens Objective Lens
Stage Clips
Diaphragm Coarse Focus Knob
Fine focus Knob Light

15. What have you learned? Can you?
Name the parts of the microscope and their functions.
Use the microscope to observe biological specimens
Outline the differences between the light microscope and the electron microscope?