1. Topic 2: A Microscopic world

2. Our eyesight limits our understanding of our world
People with good eyesight can see only clear, defined images of things that are 0.1mm or larger

3. What is a microscope?
An instrument for viewing objects that are too small to be seen easily by the naked eye

4. History of the Microscope
1000
Reading stone
Curved outwards
Enlarged print
1284
1st wearable eye glasses

5. 1590
Hans & Zacharias Janssen experimented with multiple lenses placed in a long tube
Microscope
Objects viewed in front of the tube appeared greatly enlarged
20X magnification

6. 1665
Robert Hooke
Viewed a piece of cork through a microscope lens and noticed small “rooms”
Cells

7. 1674
New methods that provided magnifications up to 270X
Anton van Leekuwenhoek
Examined blood, yeast, insects through a microscope
1st person to describe bacteria

8. Magnifies up to 1 000 000 x! 1930s Phase-contrast microscope
Allowed for the study of colorless and transparent materials
Electron microscope
Max Knoll & Ernst Ruska
Uses electrons rather than visible light
Possible to view objects as small as the diameter of an atom
Magnifies up to x!

9. Pollen
Surface of a flower petal (1500x)
Eye of a fly
Hydrothermal worm

10. Scanning tunneling microscope
Gives 3D profiles of the surface of objects down to the atomic level
Roughness, defects

11. Workings of a Compound Microscope
Source of light
Light waves enter a glass objective lens and are bent
Bending enlarges the image
Light waves enter an ocular lens and are bent

12. The power of the microscope depends on how much each lens bends the light
Ocular Lens = 10X
Objective Lenses = 4X, 10X, 40X

13. Parts of the microscope
Label the parts of the microscope on the diagram provided
Determine the function of each part

16. Part
Function
Ocular lens
(eye piece)
Arm
Base
Coarse Adjustment Knob
Fine Adjustment Knob

17. Part
Function
Revolving Nosepiece
Objective Lenses
Stage
Stage Clips
Diaphragm
Lamp

18. To view specimen:
1. Turn on lamp
2. Center specimen in field of view
3. Focus using lowest-power objective lens (4X)
Coarse adjustment knob
Fine adjustment knob
4. Switch to medium-power (10X)
5. Focus using fine adjustment knob only

19. Keep both eyes open
Coarse adjustment knob
Use only on the lowest-power lens
Fine-adjustment knob
Use with any objective lens
Revolving nosepiece
Listen for a click when turning the lens

20. Ocular & objective lenses
Avoid touching the lenses
Clean with lens-paper
Diaphragm
Adjust to intensify or dim light for better viewing

21. Laboratory Assignment: A Microscopic World