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Microscopes
Parts and Function
Using the Microscope
Locating objects
Microscope Parts and
Function
Objective:
Given a compound-light microscope, students
will be able to identify all the parts of the
microscope with accuracy.
Eyepiece
• 1. Usually a lens of 10 power magnification
EYEPIECE
Body Tube
• 2. Holds the eyepiece
lens and objective lens
at the correct distance
for magnification
BODY TUBE
Revolving Nosepiece
• 3. Turns so that the lenses may be switched.
NOSEPIECE
Low power objective
• 4. Lens of 10 power magnification
• It is the shortest objective
LOW OBJECTIVE
High power objective
• 5. Usually a lens of 43 or 45 power magnification
• It is the lens of middle length
HIGH OBJECTIVE
Stage
• 6. Where the microscope slide is placed for viewing
STAGE
Stage Clips
• 7. Hold slide in place
STAGE CLIPS
Base
• 8. Provides firm and
steady support
BASE
Lamp
• Provides the light needed to view the specimen
LAMP
Diaphragm
• 10. Regulates the
amount of light passing
through the stage
opening.
• Turning the diaphragm
adjusts the amount of
light passing through
the slide.
DIAPHRAGM WHEEL
Arm
• 11. Supports the body tube
and the stage
ARM
Fine-wheel adjustment
• 12. Elevates or lowers
the body tube or stage a
small distance with each
turn of the knob. Brings
objects slowly into fine
focus
FINE ADJUSTMENT
Coarse-wheel adjustment
• 13. Elevates or lowers the
body tube or stage a large
distance with each turn of
the knob. Brings objects
into rapid but coarse
focus
Course Adjustment
Using the Microscope
Objective:
Given a microscope and a slide, students will
be able use and maneuver all the parts of the
microscope safely and correctly.
Moving the nosepiece to adjust the
lenses
• The lens has to be directly over the stage opening.
• The “click” lets you know that the lens is in viewing
position.
Looking through the eyepiece
• A circle of light should now
be visible. This circle of light
is called the field of view.
• Keep both eyes open to
reduce eye strain.
DO NOT SQUINT.
• The dark line on the field of
view is a pointer.
Field of View
POINTER
Adjusting the diaphragm
• Turn the wheel to
control how much light
goes through the
specimen.
• More light is not
always better.
Using the coarse wheel
adjustment
• Turning the course wheel
adjustment moves the lens up
or down in relation to the stage.
• Should be used to find the
object under low power.
Using the fine wheel adjustments
• Turning the fine wheel
adjustment also moves the lens
but very slowly.
• Should be used to focus the
specimen under high power.
Safety Concerns
• Never use the coarse wheel adjustment when the
high power objective is in position.
• WHY?
• You could bang the lens against the slide and break
the slide or worst scratch the lens.
• You may use the highest magnification lens if you
are VERY careful!!
Locating an Object under
the Microscope
Objective:
•Given a microscope and a slide, students will be able to
locate and focus objects under the microscope using the
low-power lens.
•Given a microscope and a slide, students will be able to
focus objects under the high-power lens.
What you may see today
Plant cell with cell
wall
Red cells
with dark
purple nuclei
Red blood cells
are tiny red dots
The slide shows tissue;
Cells are inside the tissue and are smaller (or very small)
Microscope lab review
• Question: What are some differences we will see
between plant and animal cells under the
microscope?
• Hypothesis: If we compare plant and animal cells,
we will see that plant cells have cell walls and
chloroplasts (not visible in all), while animal cells will
lack these because they do not require them for
support or photosynthesis.
Microscope lab review
• Look at your plant drawings. You should have two
plant cell drawings. Your drawing should show
cells. In the cell picture below you could label the
cell wall and cytoplasm at least.
cell
The cytoplasm is inside
The cell walls are
the dark edges
Microscope lab Review
• Look at your animal cell drawing. In the cell picture
below, you should be able to locate the cell
membrane, cytoplasm and nucleus
With this
Cluster of cells
You should be
Able to draw
The cell
Membrane and
nucleus
Microscope lab review
ANALYSIS QUESTIONS:
1. Cell walls, chloroplasts, and possibly large
vacuoles may be missing from animal cells.
2. Animal cells are more blob-like and without
specific shape
3. Animal cells do not do photosynthesis. Their cells
do not need the structure and support of a cell
wall.
Microscope lab review
• 4. Plants need chloroplasts for photosynthesis and
cell walls for structure and support.
• 5. Yes. My plant cell drawing included a cell wall
and some chloroplasts (depending on slide) and my
animal cell drawings lacked both of these.
Preparing a Wet Mount
• A temporary wet mount consist
of some object placed in a drop
of water on a slide with a
coverslip over the object.
•Make sure you lower the
coverslip slowly to avoid air
bubbles.
PRACTICE
Using the microscope to view your
wet mount
• Always start with the low
power objective in
position.
• Place slide on stage so
that specimen is directly
over stage opening.
PRACTICE
Using the microscope to view your
wet mount
•
•
Use the coarse adjustment to
make the distance between
the objective lens and stage
as close as possible without
touching the slide.
NEVER lower the objective
toward the stage while
looking through the eyepiece.
PRACTICE
Using the microscope to view your
wet mount
•
•
•
Look through the eye piece with both eyes open
Slowly turn the coarse adjustment so the objective
moves away from the stage.
The specimen should come into focus. You may
have to center it by moving the slide on the stage.
PRACTICE
Using the microscope to view your
wet mount
• Use the fine adjustment to bring the letter into sharp
focus.
• Adjust the diaphragm as you look through the
eyepiece, and you will see that more detail is visible
when you allow in less light! Too much light will
give the specimen a washed-out appearance.
• PRACTICE
Position of objects when viewed
with a microscope
• Specimens placed on the stage of the microscope
facing you will look up side down and reversed
when viewed through the eyepiece.
• Example:
Position of objects when viewed
with a microscope
• While looking through the eyepiece if you move the
slide everything will be opposite.
• If you move slide left, it will appear to move to the
right.
• If you move the slide away from you, it will appear
to move towards you.
• EVERYTHING IS BACKWARDS!
• PRACTICE
Increasing the magnification of
the microscope
•
•
Any object to be viewed under high-power
magnification is always located first under low
power and focused.
Move the low-power objective out of viewing
position. Look first to the side of the microscope
and then turn the nosepiece. Click the high- power
objective into viewing position. VERY
IMPORTANT STEP!
Increasing the magnification of
the microscope
•
•
Look through the eyepiece. The specimen should
be visible. However, it may need to be focused.
Use only the fine-wheel adjustment to sharpen the
focus.
CAUTION: Never use the coarse-wheel
adjustment for focusing with high power. Damage
to the lens and slide may result if the coarse
wheel adjustment is used.
Finding a specimen under high
magnification.
•
If you are unable to find the specimen after you
change the objective do the following: while
looking through the eyepiece, move the glass
slide slightly to the left, right, away from, or toward
you.
When done…
a.
b.
c.
The nosepiece should
be in the low power lens
position.
The stage is at the
lowest position.
Clean the lenses with a
lens wipe. Cleaning with
a tissue or anything else
might scratch the lens.
Clean Up
• After each activity clean and dry slide and cover slip
• After you finish the lab
–
–
–
–
Prepare microscope for storage
Clean and dry the slide and cover slip
Throw away onion and toothpick
Clean counter area, make sure everything looks like you
found it
– Wash your hands
– Sit down
What MIGHT I see under the
microscope?
Looking at elodea, cheek cells, and
pond water
Lab Expectations
• 1. Make ONE of each slide: one cheek cell, one
elodea, and one pond water (only need one or
two drops of pond water-get some grime.)
• 2. THROW AWAY TOOTH PICKS AFTER USE. DO
NOT USE TOOTH PICKS FOR ANYTHING ELSE.
• 3. Wash each slide under running water and then
rinse with peroxide solution and dropper. Wipe
dry with paper towel and put back like they were!
• Everything goes back like it was and looks good
for next group please.
Elodea
• Elodea
Cytoplasm
Elodea cells
Chloroplasts
Cell Wall
Human cheek cells
• Each small purple/pink structure is a cell with
a darker nucleus
Pond water critters
• You will see a mess of “stuff” maybe some of
it moving! Maybe some larger critters!