Download Part #1: Using Microscopes

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Name_______________________________________
Block__________
Part #1: Using Microscopes
Purpose
To learn how to use a compound and dissecting microscope.
Be sure to draw your samples as accurately as you can and answer all of the bulleted
questions! Always include the specimen name and the correct total magnification.
1. Carefully remove the compound microscope (single eyepiece) from under your lab
table. Always keep the cover on the microscope when it is not in use.
Complete the following table in your lab notebook
Look at each objective lens for the DIN number, this is the magnification of that objective.
Eyepiece (ocular) magnification
__________X
Scanning objective (Red) magnification
__________X
Low power (Yellow) objective magnification
__________X
High power (Blue) objective magnification
__________X
Oil immersion (White) objective magnification
__________X
Complete the following table in your lab notebook
Eyepiece X
5
10
5
20
Objective X Total Magnification X
10
5
20
15
25
100
500
1500
2. Plug your microscope in and turn on the light.
3. Make sure the stage is all the way down and that the shortest objective (Red) is in
place.
4. Clean all the objectives and eyepiece with lens paper and cleaner. DO NOT USE
PAPER TOWEL!
5. Secure a prepared slide of paramecium to the stage of the microscope and focus
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under low power (yellow). Use the course adjustment.
6. Turn the high power objective (blue) into place and focus. Use the FINE COURSE
ADJUSTMENT ONLY!
7. Draw exactly what you see in the field of view (the area you see). Use colored
pencils and be as accurate as possible.
Specimen______________________
Magnification_______
Making a Wet Mount
8. Cut a letter (e) or (r) out from the classified section of a newspaper.
9. Place the letter onto a clean slide; add one drop of water, and then the cover slip.
Make sure you do not get any air bubbles.
10. Place your wet mount on the microscope stage with the letter facing you. Using the
low­power objective, center and focus the microscope on the letter. Draw the letter
as you see it.
Specimen_________________________
Magnification_______________
11. Next, switch to high power and focus the microscope.
● What happens to the image of the letter as you go from low power to high
power?
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12. As you look through the eyepiece, slowly adjust the diaphragm to obtain the
appropriate light for viewing.
● What happens as you adjust the diaphragm?
13. Switch the microscope back to low power. As you look into the microscope, use
your fingers to move the slide to the right and then to the left.
● What happens to the image as you move the slide to the right?
● What happens to the image as you move the slide to the left?
● Move the slide away from you, and record what happens to the image?
Depth of Field Focusing
14. Make a wet mount of two hairs crossing each other. Make sure you add water and a
cover slip.
15. Under low power, adjust the slide on the stage so that the point where the hairs
cross is in the center of your field of vision and then focus.
● Can you see both hairs in focus at the same time or are they too thick?
16. Switch to high power.
● Using the fine adjustment, can you see both threads in focus at the same
time?
17. Focus on one part of the hair on high power and draw exactly what you see in color.
Specimen_________________________
Magnification______________
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At this point you should be ready to focus on a slide for your
teacher without help. Ask for the correct slide and for your
teacher to mess up your microscope. This is worth up to 10 quiz
points!
18. Clean up all slides and cover slips and return to microscope tray.
Lower the stage of the microscope and switch to the shortest objective.
Part #2: Comparing Compound and Dissecting
Microscopes
1. Carefully remove the dissecting microscope (two eyepieces) from under your lab
table. Always keep the cover on the microscope when it is not in use.
2. What is the magnification of the lowest power?_________ Highest power?________
3. How does the working distance affect the size of objects that can be viewed under
the dissecting microscope compared to the compound microscope?
4. Lay your hand on the stage of the stereomicroscope. Focus on the back of your
hand and draw exactly what you see in color.
Specimen_________________________
Magnification________________
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5. Compare the movement of your hand seen through the eyepieces to the direction
you moved your hand. Is it the same as in a compound microscope? Explain.
6. Compound light microscopes work by having light pass through the objects to be
viewed. However, not all objects are translucent (see through). Some objects are
opaque (not see through); light cannot pass through them. Make wet mounts of a
onion skin and a small piece of leaf. Observe both under low power.
● How does your view of onion skin compare to your view of the Leaf? Is one
specimen more opaque?
● If an opaque object is viewed through a compound light microscope, what will
you see?
7. Place a leaf under the dissecting microscope. Focus on the highest power and draw
exactly what you see in color.
Specimen_________________________
Magnification____________
8. How come you can see the leaf with a dissecting microscope, but not with a
compound light microscope?
9. Place either a coin or paper money under the dissecting microscope and focus on
the eye of the person on the money. Draw exactly what you see in color.
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Specimen________________________
Magnification____________
Review of Microscopes
1. Place an X in each box that applies.
Compound Dissecting Both
Microscope Microscope
Has one eyepiece
Used to view specimens too small to
see with a naked eye
Has both course and fine adjustments
Used to view parts of a dissected
animal
Has objective lenses
Views objects in 3D
Uses light to help see the specimen
Used to view the surface of a leaf
Has stronger total magnification
Used to view blood cells
Appears to invert and reverse the
specimen
Can be used only on translucent
specimens
Used for view unicellular organisms
2. Under which power, high or low, is the largest field of view?
3. What happens to the field of view when you switch from low power to high power?
4. If a microorganism were swimming from right to left across your field of view under
a compound light microscope, which way would you move the microscope slide to
keep it in view? Why?
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5. If the same microorganism as above were swimming from right to left across your
field of view under a dissecting microscope, which way would you mover the
microscope slide to keep it in view? Why?
6. Take a sample of pond water and make a wet mount. Look for moving organisms
under high power. Find one microorganisms and draw it in color.
Magnification________________
If the microorganisms are moving too fast, add a drop of protoslo to your sample.
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Choose a minimum of any TWO extra specimens to examine. Make sure you write
down the name of the specimen and the magnification used for best viewing. Below
you will find a list of ideas, but anything that has microscopic structure will work.
Possible specimens:
● Cheek cell stained with methylene blue
Scrape the inside of your cheek with a tooth pick
Rub the goo you collect on a slide and mix with a drop of methylene blue
● Yeast cell stained with methylene blue
● Onion skin stained with iodine
● Cork slice
● Pollen grain
● Aquarium rock water
● Anything else?
Specimen________________________
Magnification____________
Specimen________________________
Magnification____________