# Lab _1 Compound Microscope Lab_1_

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```					                              Lab #1 Compound Microscope Lab

A compound microscope has 2 lenses, the light passes through the specimen and into the first
lens called the objective which causes the light rays from the specimen to spread apart,
forming an enlarged image of the specimen. The second lens called the ocular lens (eyepiece),
focuses and further enlarges the image.

Part A: Parts of a Microscope
On your paper, Work with the people at your lab bench to label the parts of the microscope
indicated by the letters “A” through “L”
Part B: Exploring Microscope Function

1. Obtain a microscope from the front, keeping in mind the proper way to carry this very
expensive instrument. Set it down away from the edge of the lab bench, plug it into the outlet
and turn it on.

2. Make sure that the low power objective (scanning power) which is the shorter of the 3
objectives is locked into viewing position.

3. Adjust the diaphragm to the largest opening so that the most light enters the microscope.
You can tell this by looking through the ocular eyepiece.

4. While standing behind the microscope and looking at it from the side, slowly turn the course
adjustment knob one-half turn towards you.
1. In what direction does the revolving nosepiece move?

5. Continue to turn the course adjustment until the low power objective is about 3cm from the
stage.

6. Look at the number followed by an “X” on the side of each objective. The number is the
objective’s magnifying power. The “X” stands for times. Thus the number tells how many times
an object is magnified by this lens.
2. What is the magnifying power of the low-power objective?

7. Locate the high-power objective.
3. What is its magnifying power?

8. The ocular lens has its own magnifying power. To calculate the total magnifying powers of
the microscope multiply the magnification of the ocular by the magnification of the objective
being used.
4. What is the magnifying power of the ocular eyepiece?

5. Calculate the total magnification produced when the low-power objective is used?
Calculate total magnification under high power. Show your work!

Part C: Preparing & Examining A Wet Mount

9. Obtain a piece of newspaper. Cut a 1 cm square of paper with a letter near the center.

10. Place the square in the middle of a clean slide. Using an eyedropper, put 1 drop of water on
the square, being careful not to touch the paper with the eyedropper as it may stick to it.
11. Cover your wet mount with a cover slip, this can be easily done by holding the cover slip at
about a 45 degree angle to the slide and move it towards the drop. As the water touches the
cover slip, it will spread along the edge. Gently lower the cover slip into place. A good wet
mount is free of bubbles, if you get bubbles, take off cover slip, absorb water with paper towel,
add another drop of water, and put a clean cover slip on.
(I will demonstrate how to make a wet mount at the front of the room)

12. Click the low power objective into place; make sure the diaphragm is wide open allowing max
amount of light.
13. Check bottom of slide to make sure it’s dry before placing it on the stage. Open up the stage
clips and set it on the stage so that the letter is in reading position and over the hole in the
stage. Release the stage clips gently so as not to crack the slide.
14. Look at the microscope from the side. Use the course adjustment to lower the revolving
nosepiece until the objective is about 0.5 - 1cm above the slide or until you feel an automatic
stop.
15. Looking through the ocular, keeping both eyes open (avoids eye strain).

16. Slowly raise the revolving nosepiece by turning the course adjustment toward you until the
letter comes into focus. Use the fine focus adjustment knob to sharpen the focus. Observe the
letter.
6. On a blank sheet given, draw the letter so that it is the size of half the page.
Remember to include the total magnification at the lower right of you sketch. Also, you
should include the scale bar.

17. Move the slide to the left.
7. Which way does the image move?

18. Move the slide to the right.
8. Which way does the image move?

19. Move the slide backwards and forward.
9. Which ways does the image move?

20. Observe the wet mount as you change the diaphragm to each of its settings.
10. What does the diaphragm control?

21. Make sure the specimen is in sharp focus in the center of the low power field of view. Click
the medium power objective into place watching from the side to make sure that the objective
does not hit the slide but expect it to be very close!. All focusing under medium & high power
is done with the fine adjustment knob.
11. Is the field of view larger under high or low power?

12. Compare the brightness of the field under high and low power.

Part D: Analysis and Interpretations

1. Why should a wet mount have no bubbles?
2. What did the microscope do to the image of the letter?
3. Why must you center and focus the object in the field of view under low power before
switching to high power?
4. Why is only the fine adjustment used for high power?
5. If you were scanning a slide to find a particular area, which objective would be better to use?
Why?
Lab #1 Compound Microscope Lab
NAME: ________________________                     DATE: ________________
Part A:
A __________             E __________                 I ___________
B __________             F __________                 J ___________
C __________             G __________                 K __________
D __________             H __________                 L ___________

Part B:
1. _____________

2. _____________

3. _____________

4. _____________

5. ________________________________________________
Part C:

7.__________________________

8.__________________________

9.__________________________

10._________________________

11._________________________

12._________________________

Part D:
1.________________________________________

2.________________________________________

3.________________________________________

4.________________________________________

5.________________________________________

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