Using the Microscope
Lab 1
Biology 101
Today in Lab
1. Lab etiquette/safety
- Sign and turn in the first page of the manual
3. Using the microscope
4. Find something neat – Use pond water, prepared
slides, go outside and find something, your choice.
5. Don’t forget! QHMs for next week!
What did the invention of the
microscope enable?
• DUH…. to look at tiny stuff
• Individual cells could be observed
– Allowed scientists to see that all cells
are very similar, but often take on
different functions
• Allowed us to see very small things
– Typical cell = 0.02 mm
– Our eyes can only see 0.2 mm
• Invented around 1675; telescopes
around 1605.
• Fundamentally changed how we
saw ourselves and nature.
Dutch Inventor: Antoni van
Leeuwennhoek
Determining Total Magnification
Multiply the magnification of each set of lenses:
Total magnification =
magnification of objective
X
magnification of eyepiece
Scanning power:
10
4
eyepiece ______x
times objective _____x
Low power:
eyepiece ______x times objective _____x
High power:
eyepiece ______x times objective _____x
Oil immersion power:
eyepiece ______x times objective _____x
40
= _____x
= _____x
= _____x
= _____x
Page 4, lab manual
Magnification vs. Resolving Power
• Magnification
Def: ratio of image size to actual size;
an apparent enlargement of an
object.
• Resolving Power - resolution
Def: a microscope’s ability to
distinguish between two objects
that are very close together as
separate; what allows us to see
detail.
Parts of the Compound Microscope
Using the Microscope
ATTENTION! Important to follow these steps:
1. Plug in and turn on the light source. Adjust light source as needed.
2. Clean the objectives and eyepieces with lens paper
3. Move the stage to its lowest position.
4. Make sure the lowest objective is in place (4x).
5. Place the slide on the stage and secure it with the slide clips/holder.
6. Use the stage controls to center the slide over the light source. Look at the slide from
the side of the microscope, not through the eyepieces.
7. Looking through the eyepieces, use the coarse adjustment knob to bring the slide
toward the objective. Soon you will see the image come into view.
8. After you get the image as clear as possible with the coarse adjustment, use the fine
adjustment knob to further focus the image.
9. You may now go to a higher objective if you want, but be sure to ONLY use the fine
adjustment knob to focus. (Also, be sure you are going to the next highest objective
and NOT the oil immersion). The microscope objectives should be parfocal, as an
image is focused with one objective, it will also be in focus in the other objectives.
Field of View
We will be using a ruler to measure the field of view.
What is the field of view in this image?
7 mm
Micrometer
The images we will be looking at under the microscope are
often too small to be measured in millimeters.
Thus, we use the micrometer…
1 mm = 1000 µm
1 µm = 0.001 mm
Preparing a Wet Mount
Oil Immersion
• PLEASE be very careful!!
Procedure:
1. After focusing in the high power objective, move
the nosepiece half way between this and the oil
immersion objective.
2. Place a small drop of oil on the coverslip.
3. Move the oil immersion objective into and
through the oil and secure in position.
4. ONLY use the fine adjustment (and only a little
bit) to focus
Oil Immersion cont.
• After you are finished, be sure to wipe the oil immersion lens
with LENS paper and LENS CLEANER to remove the oil. ONLY
use lens paper or else you will damage the objectives.
• Seriously. Use lens paper, not Kimwipes.
REMINDERS:
•
•
•
•
Work productively and efficiently
Think creatively, critically, and freely. ASK QUESTIONS!
Return materials in the same condition you found them
Take thorough notes, draw pictures, answer all questions in your lab
notebook, and come up with a QHM on microorganisms or something you
saw today.
• Before you leave make sure your work station is in the same condition as
you found it.
• Don’t forget! Question + Hypothesis + Methods! = QHM
• Also: be sure you have provided an email, know how to access the
website, and have spoken with me personally if you are concerned about
your writing ability and the research paper.