Emily Cocq
4B
Mr. Boyer
Biology I
Microscope Lab Activity
Introduction:
Microscopes are an amazing invention; able to observe specimens to the
tiniest degree. No matter how small, we are able to view an endless amount of life
forms, all because of microscopic technology. Scientists are opened to a whole new
world, things undiscovered, things never seen before. Now it is open to everyone. In
our very Biology I class, we are privileged to witness one of these man-made
wonders, and it can only make us wonder how much more we don’t know. We can
only learn through observation.
Procedures:
Part I- Handling the Microscope
5. Examine the microscope and give the function of each of the parts
Part of Microscope
Ocular Lens
Revolving nosepiece
Objective lenses (Low, Medium, High
Power)
Body Tube
Stage
Arm
Iris Diaphragm
Coarse focus knob
Fine focus knob
Projection lens
Base
Power switch
Function
Views the specimen on the stage.
Turns the objective lenses.
Used to view the specimen at different
levels
Holds the revolving nosepiece and the
objective lenses.
Supports the slide.
Connects the base and barrel.
Regulates the light.
Raises and lowers the stage for focusing.
Slightly moves the stage to sharpen the
image.
Projects light up to the stage.
Supports the microscope.
Turns the projection on and off.
Part II- Wet Mount Letter “e”
6. Describe the relationship between what you see through the eyepiece and what you see
on the stage.
On the stage, the specimen looks very small to notice any detail, if it can be seen at
all. Through the eyepiece, everything is magnified, and it is as if you are looking at a
whole new subject. Colors are intensified, and the insides are all illuminated through
bright light.
7. Looking through the eyepiece, move the slide to the upper right area of the
stage. What direction does the image move?
To the upper left.
8. Now, move it to the lower left side of the stage. What direction does the image
move?
To the lower right.
10. Locate the diaphragm under the stage. Move it and record the changes in light
intensity as you do so.
As you move it to one side, the light becomes darker and the insides of the
specimen are not as illuminated. If you move it to the other side, the light becomes
brighter and the insides of the specimen are illuminated and clear.
Letter “e”
Part III- Plant and Animal Close-Up
Cheek Cells
Pond Scum
Potato Sample
Prepared Slides
Earthworm Intestine Region
Hydra Budding Adult
Spirogyra
Questions
1. Locate the numbers on the eyepiece and the low power objective and fill in the blanks
below.
Eyepiece magnification _______20X_______(X) Objective magnification
______40X________= Total Magnification ______800X_______
2. Do the same for the high power objective.
Eyepiece magnification ______20X________(X) Objective magnification
_______400X_______= Total Magnification _______8000X______
3. Write out the rule for determining total magnification of a compound microscope.
Total magnification of a compound microscope is the product of the eyepiece
magnification and the objective magnification (If there are two objective magnifications,
then the two should be multiplied together also).
Conclusion:
From working with microscopes, we have learned more about the specimens
we observed. We also learned how to handle microscopes, using the proper
techniques with the Coarse and Fine focus knobs, as well as other parts. We learned
the safe procedures when making a slide and inserting it on the stage properly.
Overall, this has been a great learning experience, to learn about the microscopes
and the specimens we’ve studied with it. No matter how much we already knew
about microscopes, we explored deeper and discovered so many new things.
Conclusion Questions:
1. Carry the microscope with both hands; one on its arm and one on its base.
Make sure that when adjusting any of the focus knobs to not hit the objective
lens, as it will damage it permanently.
2. A light microscope is also called a compound microscope, because it uses
more than one lens.
3. Images observed under a light microscope are reversed and inverted,
because, to get a clear look at a specimen, the objective lenses have to have
very short focal lengths. When light passes through the specimen and into
the objective, it passes the focal length, making the image invert and reverse.
4. The specimen must be centered in the field of view on low power before
going to high power so that the viewer can find the specimen easily, then
switch to a higher power, now focused on the object, if they want.
5.
a. Eyepiece magnification (x) Objective magnification = Total
magnification
20X (x) 10X = 200X
b. Eyepiece magnification (x) Objective magnification = Total
magnification
20X (x) 43X= 860X
6. First, cut out a letter “e” from a piece of newspaper and place it on a glass
slide. Then, use the dropper to put a drop of water onto the slide, and stick
the “e” in place with the cover slip. To add the stain, put a drop of iodine in
the solution and place the cover slip back on, cleaning off the residue with a
paper towel or tissue.
7. When going from low power to high power on a compound microscope, the
field of view becomes greater and the amount of light is greater as well,
because of how close the objective lens is to the projected light.
8. The microscope user could adjust the diaphragm to suit the lighting to the
specimen.
9. Under high power, you cannot use the Coarse focus knob, for it might damage
the objective lens, therefore you must use the Fine focus knob. Also, under
high power, it is harder to focus in on the object, so you must find the object
in the field of view on low power first.
10. A stereomicroscope gives a low-power view of the subject, while a
compound microscope can view both low power and high-power.
11. An electron microscope is a microscope that only works with nonliving
materials, but has a very good resolution and can be useful in the science
world in order to observe things that have died but still wish to be used in
experiments.
Timeline
1590 – Compound microscope invented by Hans and Zacharias Jansen, Dutch
spectacle maker
1827 – Achromatic microscope lens developed by Giovanni Amici
1838 – Cell theory proposed by Schleiden and Schwann
1882 – Movement of cells within living organisms observed by Metchnikoff
1932 – Electron microscope invented by Ernst Ruska