# Using a Compound Light Microscope LAB

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```					                           Using a Compound Light Microscope

Robert Hooke helped us begin our journey toward understanding the cell by using a
microscope to view a thin slice of cork. After viewing the microscopic image of the
thin slice of cork (type of tree), he coined the term “cell” for the first time. The cells
were dead when Hooke viewed them, so Leeuwenhoek was totally surprised when he
viewed pond water and noticed things moving around. AHH! He called them
“beasties” and “animacules”. Leeuwenhoek was the first to view living cells.

Today you will practice using an advanced version of Hooke’s microscope, the Compound Light
Microscope. Refer to the figure below during the lab. In this investigation, we will learn how to make
a wet-mount slide and how to observe an object under the microscope.

Robert Hooke                Anton von Leeuwenhoek                   Wet-mount Slide
Procedure:
1. Using the tweezers, place the “d” on the center of the slide in its normal reading position.
2. Using the eye dropper, carefully place one drop of water over the letter.
3. Place a clean coverslip at the end of the drop of water at a 45 degree angle (see picture on page
one). Then release the coverslip letting the motion push out any air from under the cover slip. Be
sure no air bubbles are under the cover slip. Air bubbles will interfere with clear viewing of the
specimen. If they are present make another wet-mount slide.
4. Absorb excess water by touching a folder piece of paper towel to the water that comes out around
the edges of the coverslip.
5. Look at your microscope and on your answer sheet (1) write down the magnification of each
of the objectives of your microscope? What is the magnification of your eyepiece?
6. Now multiply the eye piece by the low power objective to find out the total magnification.
7. Using this same multiplying procedure, find the highest magnification of your microscope
8. On your answer sheet (4), draw what your slide looks like as you look at it with the naked
eye.
9. Place the slide under the clips on the stage of the microscope . Position the slide so that the letter
“d” is directly over the center of the stage opening.
10. Turn the nosepiece so that the low-power objective is facing downward, toward the slide. Use the
coarse-adjustment knob to slowly lower the low-power objective until it almost touches the slide.
CAUTION: To prevent damage, do not lower the coarse adjustment while looking through the
eyepiece.
11. Use the fine-adjustment knob to focus the letter clearly. You should only need to turn the knob
one-quarter of a turn or less.
12. On your answer sheet (5), draw what you see through the viewing circle of the microscope
using the low power objective lens. Record the magnification you are using. HINT: It is not a
“d” when you see it!
13. While looking through the eyepiece, move the slide to the left. Notice which way the slide
actually moves. Now try moving the slide to the right and again notice which way the letter seems
to move.
14. CAUTION: The high power objective is longer than the low-power objective; it may easily touch
and damage the slide. Look at the side of the microscope when switching to the high-power
objective to make sure it clears the slide. Switch to the high-power lens by revolving the nosepiece
so that the high-power lens clicks in place. Use the fine adjustment knob ONLY to bring the
specimen into focus.
15. On your answer sheet (6), draw what you see through the viewing circle of the microscope
using the high power objective lens. Record the magnification you are using.
16. Now answer the Analyze and Conclude Questions 7-11.
17. If you finish these with time remaining in class, turn in your paper to the box, straighten your area
(put everything back where it was when you started), and then view some of the sample slides
from the teacher’s desk.
18. When the bell sounds, place everything back in its original position and turn off your microscope!
Using a Compound Light Micrscope            Name_____________________

1) What is the magnification of each objective of your microscope? _______ ,_______
,_______ What is the magnification of your eyepiece?________________

2) What is the total magnification power using the low-power objective? _________

3) What is the highest magnification of our microscope? _____________
4)                                 5)                         6)
Letter “d” without microscope      Low-power Objective        High Power Objective

Magnification:_______ Magnification:_______
Analyze and Conclude:
7) How does the letter “d” appear as seen through the microscope differ from the way a
“d” normally appears?
______________________________________________________________________

______________________________________________________________________
8) When you move the slide to the left, in what direction does the letter “d” appear to
move?
_______________________________________________________________
9) When you move the slide to the right, in what direction does the letter “d” appear to
move?
____________________________________________________________
10) Could you actually see the entire letter when using the high power? _______ Describe
what you saw through the viewing area when looking at the “d” using high
power.____________________________________________________________

______________________________________________________________________
How did the ink that was used to print the letter differ in appearance when you saw it
with the unaided eye compared with the way it appears under the microscope? ________

____________________________________________________________________________
11) Using numbered steps, describe how to make a wet-mount slide.
1___________________________________________________________________________
2___________________________________________________________________________
3___________________________________________________________________________
4___________________________________________________________________________
5___________________________________________________________________________
Use the back if you would like more space. Just draw an arrow please.
Using a Compound Light Micrscope            Name_____________________

1) What is the magnification of each objective of your microscope? _______ ,_______
,_______ What is the magnification of your eyepiece?________________

2) What is the total magnification power using the low-power objective? _________

3) What is the highest magnification of our microscope? _____________
4)                                 5)                        6)
Letter “d” without microscope      Low-power Objective        High Power Objective

Magnification:_______ Magnification:_______
Analyze and Conclude:
7) How does the letter “d” appear as seen through the microscope differ from the way a
“d” normally appears?
______________________________________________________________________

______________________________________________________________________
8) When you move the slide to the left, in what direction does the letter “d” appear to
move?
_______________________________________________________________
9) When you move the slide to the right, in what direction does the letter “d” appear to
move?
____________________________________________________________
10) Could you actually see the entire letter when using the high power? _______ Describe
what you saw through the viewing area when looking at the “d” using high
power.____________________________________________________________

______________________________________________________________________
How did the ink that was used to print the letter differ in appearance when you saw it
with the unaided eye compared with the way it appears under the microscope? ________

____________________________________________________________________________
11) Using numbered steps, describe how to make a wet-mount slide.
1___________________________________________________________________________
2___________________________________________________________________________
3___________________________________________________________________________
4___________________________________________________________________________
5___________________________________________________________________________
Use the back if you would like more space. Just draw an arrow please.

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