Notes 7.1~ Key
1. Ocular Lens
2. Body tube
3. Arm
4. Nose Piece
5. Objective lenses
6. Mechanical stage clip
7. Diaphragm lever
8. Iris diaphragm
9. Condenser
10. Light source
11. Course focus adjustment
12. Fine focus adjustment
13. Light switch
14. Base
Lowest Total Magnification: 40x
Highest Total Magnification: 400x
When using the highest power
objective you should only use
the___fine_________ focus
adjustment.
Functions:
Arm: supports the tube and connects it to the base
Base: bottom of microscope, used for support
Stage: the flat surface you put your slides or samples
Body Tube: Connects the eye piece to the objective lenses
Stage Clips: Holds the slides in place on the stage
Eye Piece Lens: the part of the microscope closest to your eye, a lens look through (10 or 15 X)- usually
10X
Revolving Nose Piece: holds the objectives
Diaphragm: adjusts the amount of light shining through the sample on the stage
Objective Lenses: 3-4 lenses usually 4,10,40 (some microscopes have 10,40,60)
Low power objective: 4X
Medium power objective: 10X
High power objective: 40X
When bringing a specimen into focus you begin by using the low power objective. Then continue switching to
the medium power objective and then the high power objective.
Fine focus knob: small knob used to change the position of the body tube by making small adjustments to
focus
Coarse focus knob: large knob used to adjust the position of the body tube, allowing you to quickly bring
your sample into view
Light source: increases the amount of light shining through your sample
Resolution: the amount of detail you can see in an image
Magnification: How much an image is enlarged under a microscope
Total magnification: eye piece lens X objective lens
History of the Microscope
-Microscopes enable scientists to view and study cells- basic units of all living things
-Light MicroscopesLeeuwenhoek – first to use a simple light microscope and discovers single-celled, animal like organisms
now called protozoans (1683)
-Compound light microscope - uses a series of lenses to magnify objects in steps  using objective lenses 
this is the type of microscope we will use.
1880-1890- Louis Pasteur and Robert Koch, using compound microscopes, pioneered the study of bacteria
-Compound light microscopes: Uses a beam of light that can magnify up to 1500 times its actual size.
- Robert Hooke: used a compound microscope to study Cork, the dead cells of oak bark. (1665)
-Electron Microscopes- Uses a beam of electrons instead of light to magnify structures up to 500,000 times their actual size This
allows scientists to see structures within a cell.
- 3 types of electron microscopes1) SEM- scanning electron microscope (1935)
-Scans surface of cells to learn 3-D shape
-viewing nonliving organisms
2) TEM- transmission electron microscope (1931)
- Used to study the structures contained within a cell
-view nonliving organisms
3) STM- scanning tunneling microscope (1981)
-Used to produce a three-dimensional image of an objects surface.
-Can view living organisms
-Can view things as small as atoms, shows DNA,