LEARNING ABOUT SCIENTIFIC
EQUIPMENT: THE COMPOUND
MICROSCOPE
Introduction
Historians believe that the first compound microscope was invented
by a Dutch spectacle-maker, Zacharias Janssen (1580–1638). The
compound microscope uses lenses and light to magnify an image.
A compound microscope gets its name from the fact that it has two
systems of lenses for greater magnification. To properly use a
microscope, you need to know the parts of a microscope and what
the parts do. In this activity, you will learn the parts of a
microscope.
Time Needed
20 minutes
What You Need
compound microscope
lined paper, one sheet
pen or pencil
Safety Precautions
Please review and follow the safety guidelines.
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…SCIENTIFIC EQUIPMENT: THE COMPOUND MICROSCOPE
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What You Do
1. Study the parts of the compound microscope (Figure 1) and the
function of each part, as listed below and on the next page.
Figure 1
Eyepiece lens: the lens through which you look, usually
magnifies objects 10 times (10⫻).
Tube: connects the objective lenses to the eyepiece lens
Coarse focus: used to bring specimen into focus
Fine focus: allows for minor adjustments in focus, used under
high power
Revolving nosepiece: rotating piece that holds the objective
lenses
Objective lenses: low-, medium-, and high-power lenses that
allow you to magnify objects by different amounts, usually
between 10⫻ and 100⫻, which, combined with the
magnification of the eyepiece lens, allow you to magnify objects
anywhere from 100⫻ to 1,000⫻.
Rack stop: prevents you from smashing the high-power lens into
the slide
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…SCIENTIFIC EQUIPMENT: THE COMPOUND MICROSCOPE
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Stage: the platform where you put your slides, and which has
clips to hold the slides in place
Arm: connects the tube to the base
Illuminator, provides the light so you can view the specimen
Base: supports the microscope
How to Use the Compound Microscope
(From: http://www.microscope-microscope.org/activities/school/microscope-use.htm)
1. When moving your microscope, always carry it with both hands
(Figure 2). Grasp the arm with one hand and place the other
hand under the base for support.
2. Turn the revolving nosepiece so that the lowest-power objective
lens is "clicked" into position.
3. Place the microscope slide on the stage and fasten it with the
stage clips. You can push down on the back end of the stage
clip to open it.
4. Using the coarse adjustment, lower the objective lens down as
far as it will go without touching the slide! Note: Look at the
slide and lens from the side when doing this (see Figure 3).
5. Look through the eyepiece and adjust the illuminator (or mirror)
and diaphragm (Figure 4) for the greatest amount of light.
Figure 2
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Figure 3
Figure 4
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6. Slowly turn the coarse adjustment so that the objective lens
goes up (away from the slide). Continue until the image comes
into focus. Use the fine adjustment, if available, for fine
focusing.
7. Move the microscope slide around so that the image is in the
center of the field of view, and readjust the mirror, illuminator, or
diaphragm for the clearest image.
8. You should be able to change to the next objective lenses with
only slight focusing adjustment. Use the fine adjustment, if
available. If you cannot focus on your specimen, repeat steps 4
through 7 with the higher-power objective lens in place. Do not
allow the lens to touch the slide!
9. The proper way to use a monocular microscope is to look
through the eyepiece with one eye and keep the other eye open
(this helps avoid eye strain). If you have to close one eye when
looking into the microscope, it's OK. Remember, everything is
upside down and backwards. When you move the slide to the
right, the image goes to the left!
10. Do not touch the glass part of the lenses with your fingers.
Use only special lens paper to clean the lenses.
11. When finished, raise the tube, click the low-power lens into
position, and remove the slide.
Observations
1. After studying the parts of the microscope, look at a real
microscope and see how many parts you remembered. Could
you name them all?
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…SCIENTIFIC EQUIPMENT: THE COMPOUND MICROSCOPE
2. On a piece of paper, list the explanation of each part of the
microscope listed below:
Eyepiece lens:
Tube:
Coarse focus:
Fine focus:
Revolving nosepiece:
Objective lenses:
Rack stop:
Stage:
Arm:
Illuminator:
Base:
3. When would you use a microscope?
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5
SAFETY PRECAUTIONS
Review Before Starting Any Experiment
GENERAL
obtain your teacher’s permission for experiments
• Always
performed at school, and obtain your parent’s permission for
experiments performed at home, before attempting any
experiment.
all instructions for an experiment several times before
• Read
starting the experiment, and follow the directions exactly.
an experiment requires adult supervision, do not perform the
• Ifexperiment
unless you have an adult supervising you the entire
time you are performing the experiment.
your hands before the start of and after each experiment
• Wash
you perform.
• Keep your work area clean.
eat or drink while performing a lab experiment. Never taste
• Never
a substance used in an experiment unless you are told that it is
safe to do so.
aware of the location of safety equipment you may need in an
• Be
emergency, such as running water, an eyewash if you are at
school, and a fire extinguisher.
you are going outside, make sure you have permission to go
• Iffrom
your teacher and parent. Take a buddy with you, and dress
appropriately for the weather. Make sure you or someone who
accompanies you is familiar with the area, and bring along a
first-aid kit in case of an emergency.
• Never look directly into the Sun.
CHEMICAL SAFETY
wear goggles when working with chemicals, such as acids
• Always
and bases, and near heat sources like flames. If at all possible,
avoid wearing contact lenses when working with chemicals.
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SAFETY PRECAUTIONS
2
any substance gets into your eyes, notify an adult (e.g., your
• Ifteacher
or parent) immediately, and flush your eyes with running
water for at least 15 or more minutes. Do not mix chemicals
unless you are told to do so by a teacher or parent.
• Never touch, taste, or smell chemicals unless instructed to do so.
• Keep chemicals in closed containers when they are not in use.
of all used chemicals properly. Do not pour any
• Dispose
chemicals or solids down the drain unless instructed to do so.
safety gloves and a plastic apron when handling chemicals.
• Use
If any chemicals spill on your skin, rinse the affected area with
running water for at least 10 minutes, and notify your teacher or
parent immediately.
precautions to avoid spilling chemicals. If a chemical spills
• Take
on any surface, notify your teacher or parent immediately to
assist with clean-up.
caution when using sharp instruments such as knives or
• Exercise
scissors. Always cut away from yourself, not toward yourself. If
you cut yourself, notify your teacher or parent immediately.
GLASSWARE
• Clean glassware when you are finished with the experiment.
careful when using glassware. If a piece of glassware breaks,
• Be
have an adult assist you in clean-up to avoid injuries from broken
glass. Never use broken or damaged glassware.
FIRE SAFETY
not heat glassware that is not completely dry. Do not pick up
• Do
hot glassware without heat-resistant gloves or tongs.
heating glassware, keep it away from yourself and from
• When
others.
not heat anything unless instructed to do so by a teacher
• Do
or parent.
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SAFETY PRECAUTIONS
3
• Do not heat substances in a closed container.
an experiment, make sure that all heating sources are off
• After
and that all flames have been put out.
• Do not reach across such heating sources as flames.
you have long hair, tie it back, out of the way. Do not wear
• Ifclothing
with loose sleeves, scarves, bows, ties, or anything else
that may hang into a fire. Do not wear long earrings.
ELECTRICAL SAFETY
• Do not touch electrical equipment when your hands are wet.
not plug many electrical devices into one outlet or use an
• Do
extension cord.
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