1. Parts of the Compound Light Microscope

2. Microscope Parts and Functions
Slide # 2
Microscope Parts and Functions A B C D E F M L K H G J I
B. Arm: supports tube & connects it to the base
C. Stage Clip: holds microscope slide in place
D. Coarse adjustment: raises / lowers stage to bring image into focus
E. Fine adjustment: brings image into sharp focus
F. Base: Supports microscope
G. Illuminator: Light source
A. Eyepiece: Holds ocular lens; lens that you look through; magnified image of objective lens

3. Microscope Parts and Functions
Slide # 3
Microscope Parts and Functions A B C D E F M L K H G J I
I. Stage: platform that holds the slide
J. Microscope slide: holds the specimen
K. Objective lenses: magnifies the specimen
Shortest lens has least magnification
Longest lens has greatest magnification
H. Diaphragm: Controls the amount of light that passes through a specimen

4. Microscope Parts and Functions
Slide # 4
Microscope Parts and Functions A B C D E F M L K H G J I
L. Revolving nosepiece: holds 2 or more objective lenses
M. Body tube: Connects eyepiece to objective lens

5. How to Calculate Magnification
Slide # 5
How to Calculate Magnification
Magnification of eyepiece X magnification of objective lens
If eyepiece is 10 x and objective lens is 4x, then what is the total magnification?
10x X 4x = 40X

6. Slide # 6
TAKS PRACTICE
A student wants to view cells under the compound microscope at a total magnification of 400X. If the eyepiece is 10X, which of the following objective lenses should be used?
A 4X
B 10X
C 40X
D 100X
How do we calculate magnification?
Eyepiece X Objective lens = Total magnification
Correct Answer = C
10x X n = 400x
10x = 10x
n = 40x

7. How a Light Microscope Works
Slide # 7
Use lenses to make small objects appear larger
Compound light microscope: Two lenses separated by a tube
Lenses magnify an object by bending the light that passes through the lens
Magnification: ability to make things appear larger than they are
Resolution: fineness of detail that can be seen in an image
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8. Slide # 8
Microscope Safety
1. Always use 2 hands to carry a microscope; one on the arm and one hand supporting the base
2. Only use lens tissue to clean lenses
3. When focusing, always look to the side to watch and make sure the objective lens doesn’t hit the slide
4. Always use the lowest power (shortest) objective lens for bringing specimen into focus
Bring specimen into focus by first using coarse adjustment, then use fine adjustment
Never use a microscope with a frayed cord
Because we have running water in our lab area, NEVER turn on the water when using a microscope

9. How to Prepare a Slide 1. Place slide on a flat surface.
Place a drop of water on the slide.
Add the specimen to the drop of water (at times, you may want to have the specimen already on the slide before adding the water).
3. Hold the coverslip by its sides and lay its bottom edge on the slide close to the specimen. Holding the coverslip at a 45° angle helps.
4. Slowly lower the coverslip so that it spreads the water out. If you get air bubbles (looking like little black doughnuts), gently press on the coverslip to move them to the edge. If there are dry areas under the coverslip, add a little more water at the edge of the coverslip. Too much water can be dabbed off with a piece of paper towel

10. Slide # 9
How to Prepare a Slide
The diagram below shows how a cover-slip should be lowered onto some single-celled organisms during the preparation of a wet mount.
Why is this a preferred procedure?
A The cover-slip will prevent the slide from breaking.
B The organisms will be more evenly distributed.
C The possibility of breaking the cover-slip is reduced.
D The possibility of trapping air bubbles is reduced.