Upper Merion Area High School Biology
Microscope Lab
Name______
Background: What is a Compound Microscope?
What is the range of magnification of the Compound microscope?
The microscope is a tool, why do we use tools?
Purpose of this Lab:
Method
I. Getting to know the microscope
The following are the parts of the microscope, using the descriptions of each part and a microscope, label the picture of the microscope and answer the questions
Eyepiece- The removable lens at the top of the microscope, the part where you place your eye. What is the magnification of the eyepiece (look at your microscope) ______?
Tube- the hollow cylinder between the eyepiece and the objective lens
Nosepiece- this is attached to the base of the tube; it rotates and contains various objective lens.
Objectives- the second lens of a compound microscope, most microscopes have two or more. What are the magnifications of the various objective lenses (look at your microscope and list them all). ______
Low Power Objective- The shorter of the objective, what is its power?______
High Power objective- The longest of the objective, what is its power?______
* The maximum power of a compound microscope is determined by ______the power of the eyepiece by the power of the high power objective. What is the power of your microscope? ______.
Coarse adjustment- This is how the microscope is focused, this is usually the large of the two knobs at the side of the tube. It is used only in low power. This moves the microscope the most.
Fine adjustment- this is also how the microscope is adjusted, but only after the coarse adjustment has been used to find the specimen. It is the only adjustment used when using higher powers.
Arm- support the tube of the microscope, attaches to the stage and base.
Stage- the flat area where the specimen to be viewed is placed, usually has clips for holding the microscope slide
Spring clips- found on the stage to hold the slide.
Diaphragm- a rotating disk attached below the stage that is used to control the amount of light going through the specimen
Light source- below the stage, it maybe an electric light or a mirror for using room light.
Base- the heavy bottom of the microscope
Inclination point- a movable hinge that allows the entire microscope to be tilted back to ease the viewing.
Label Microscope
II. Preparing the microscope for use
Carrying the microscope- Use two hands one at the base, one on the arm
Clean lens with special lens paper.
Plug in and turn on light.
Open diaphragm to widest, most light setting.
Turn to low power objective.
III. The operation of the microscope
For this investigation you will prepare a specimen on a slide and view using your microscope. As you view the slide answer the questions.
A. Preparation of the slide
Place one drop of water on the slide
Cut from newspaper a single letter, the lower case “e” and place correct side up in the drop of water
Cover with a cover slip
B. Focusing the microscope
Place the slide on the stage of the microscope and hold with stage clips
Looking at the stage, bring the low power objective as close as possible to the slide using the coarse adjustment.
Now, looking through eyepiece slowly focus by moving the coarse adjust so that the stage moves away from the slide.
Once focused, use the fine focus and diaphragm to create the best image.
Low power sketch
Questions:
How does the position of the “e” in the eyepiece compare to its position on the slide?
If you move the slide to the right, does the position of the “e” move, if it does, in which direction?
If you move the slide up, does the position of the “e” move, if it does, in which direction?
Now change to high power, and refocus using only the fine adjust.
High power sketch
Questions:
When you changed to high power how does this change the field, the amount of the “e” you can see
If the “e” was not in the center under low power, what would have happened?
Is the “e” uniform, the same throughout, under high power
IV. Advanced investigation
Remove the “e” from the slide and prepare a slide using a human hair.
Observe the hair under low power, and the best light.
Low power sketch
Questions
Is the hair the same color and structure throughout?
Reduce the amount of the light, how is the image of the hair changed?
Which diaphragm setting provided the best image? ______
Rotate the fine focus back and forth, how does the image of the hair change?
Change to high power and refocus
High power sketch
Questions:
Is the hair as bright under high power as it was under low power (if you don’t remember turn back to low power)?
Can you see greater detail under high power, what do you see?
Can you see as much of the hair under high power as under low power?
Describe the different in detail of the hair under high power.
V. Conclusions
Why do you start with lower power?