Microscope Lab - Manhasset Public Schools

Name:
Date:
Microscopes
Lab #: ______
A microscope is a tool that scientists use to observe specimens that are too small for the naked eye to observe alone. This
lab will allow you to use the different parts of the microscope and create wet mounts to observe “specimens” under the
microscope.
Materials
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1 Microscope
1 Slide
2 Coverslips
1 Letter “e”
Magazine Clippings
Scissor
1 Pipette
1 Small beaker with water
Part 1: Determining Magnification
Directions: Answer the following questions based on the information given and your knowledge of microscopes
Inscribed on each objective lens is the magnification (power) of that lens. This tells the number of times the lens
magnifies the image. For example, if you are looking at a strand of hair with 4x, the hair will appear four times its actual
size. Rotate the lenses in the nosepiece until they click into position. The objective lens is always the one directly under
the body tube. Usual powers for objective lenses are 4x, 10x and 40x.
1. How many objective lenses does your microscope have? ____________________
2. In the table below, record the power of each objective on your microscope
____ X
____ X
____ X
(smallest)
(medium)
(largest)
The eyepiece (ocular) lens is the lens you use to look into the microscope. This also has a magnifying power! Locate the
eyepiece (ocular) lens. This lens is located at the top of the body tube. The ocular magnifies the image made by the
objective lens. The most common magnification of the eyepiece is 10X.
3. Using the information you collected about your objective lenses and ocular lenses, determine the total
magnification for each power of your microscope by completing the chart below.
POWER
LENS
EYEPIECE LENS
TOTAL
MAGNIFICATION
MAGNIFICATION
MAGNIFICATION
Low
x
=
Medium
x
=
High
x
=
Part 2: Using the Microscope: Preparing and Examining a Wet Mount for the Letter “e”
Read each of the following steps carefully and place a check on each line when you have finished each step
1. _____ Take a small letter “e” and a clean microscope slide
2. _____ Place the letter “e” in the middle of the clean slide.
3. _____ Take the pipette and place 1 drop of water on the letter “e”. Do not touch the pipette to the paper or else it
will stick to it
4. _____ Take a coverslip and carefully hold the cover slip at a 45 degree angle to the slide. Lower the coverslip
down towards the drop of water. One side of the coverslip will touch the water first and spread it along the
edge. Gently lower the coverslip and do not press it down or it will shatter. A good wet mount should have
no bubbles! Do not place the slide onto your microscope yet
5. _____ Set the microscope diaphragm (dial under the stage) and move it until it is at its largest opening.
6. _____ Move the nosepiece and click the low power into its place
7. _____ Take the wet mount and place it on the stage so that the letter “e” is right under the objective lens. Fasten the
slide with the stage clips
8. _____ Use the coarse adjustment knob (large knob) to lower the body tube until the objective is about 1 cm above
the slide
9. _____ Look through the eyepiece, and then slowly turn the coarse adjustment knob (large knob) until the letter
comes closer to the lens. To get the letter “e” into a much sharper focus, turn the fine adjustment knob (small
knob) until the image is completely in focus.
10. _____ Answer the Following:
a. Move the slide to the left. Which way does the image move?
b. Move the slide to the right. Which way does the image move?
c.
So, if you move the slide in one direction, the image will move in the (same/opposite) direction. Circle one
d. Draw the letter “e” under low power exactly how you see it through the microscope in the circle below.
e.
While looking into the eyepiece at your specimen, adjust the diaphragm (dial under stage) to each of its
settings. What does the diaphragm control?
11. _____ Switch from the low power objective to the high power objective.
12. _____ Adjust the fine adjustment knob as needed to get the letter “e” back in focus
13. _____ Answer the Following:
f. What does the coarse adjustment move the slide closer to?
g. What does the fine adjustment do?
h. Is the field of view (white space) larger/brighter under high power or low power?
i.
Draw the letter “e” under high power exactly how you see it through the microscope in the circle below.
Part 3: Using the Microscope: Preparing a Wet Mount to Examine Resolving Power
Resolving power is the ability to distinguish between two separate points that are very close together. Microscopes have a
resolving power greater than that of the human eye
1. _____ With a napkin, wipe off your wet mount slide for the letter “e” and throw out the “e” and the coverslip
2. _____ Your slide should be dry and empty.
3. _____ Cut approximately a 1 cm square of the magazine clippings. Try to find a very colorful area with light and
dark tones but not black.
4. _____ Answer: Using your eyes only, what colors do you see in your square?
5. _____ Prepare a wet mount for the colored square following steps #1-9 from the letter “e” wet mount
6. _____ Observe the slide under low power, then switch to high power. Examine light & dark areas of the square
7. _____ Answer: While viewing the square under the microscope, what colors do you see in your square?
Part 4: Summary Questions
1. Why should a wet mount have no bubbles?
2. Define Specimen:
3. Explain why a specimen must be viewed under the microscope:
4. Besides magnifying it, what did the microscope do to the letter “e”?
5. Why is it dangerous to use the coarse adjustment knob when viewing a specimen under high power?
6. When scanning a slide to find a specimen, which objective would be better to use? EXPLAIN WHY: