The Microscope
Learning Objectives
By the end of this topic, you will be able to:
1. Name the parts of the microscope and their functions.
2. Use the microscope to observe biological specimens
3. Know the difference between the light microscope and the electron microscope
Compound Microscopes
a. The Eyepiece Lens is the lens that you look through.b. The objective lens is the lens that is immediately above the specimen.
The microscopes used in our lab are called compound microscopes because they have two magnifying lens
The Objective LensesThere 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
Parts of the Microscope
Parts of the MicroscopePart 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
Learning CheckLabel the parts of the
Microscope
MagnificationMagnification = the magnifying power of the eyepiece lens
x the magnifying power of the objective lens.
Example:
Eyepiece lens = 10XObjective lens = 4X
Total magnification = 10 x 4= 40X
Focussing 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.
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.
ELECTRON MICROSCOPE
Electron Microscope
Uses Electrons instead of light
Electrons have much lower wavelength than light
Resolution is much better
Magnification is much greater
Images from Electron Microscope
Bacteria
Cytplasm
Platelet
Learning CheckWhat is the function of each of these parts of the Microscope?
Eyepiece Lens Objective LensStage ClipsDiaphragm Coarse Focus KnobFine focus Knob Light
What have you learned?
Can you?
1. Name the parts of the microscope and their functions.
2. Use the microscope to observe biological specimens
3. Outline the differences between the light microscope and the electron microscope
END