Download bio Introduction to the Microscope Lab Activity Part I key

Name:_________________________________
Period_____
Date_________________
Introduction to the Microscope Lab Activity Part I
Introduction
"Micro" refers to tiny, "scope" refers to view or look at. Microscopes are tools
used to enlarge images of small objects so as they can be studied. The compound
light microscope is an instrument containing two lenses, which magnifies, and a
variety of knobs to resolve (focus) the picture. Because it uses more than one
lens, it is sometimes called the compound microscope in addition to being referred
to as being a light microscope. In this lab, we will learn about the proper use and
handling of the microscope.
Instructional Objectives
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Demonstrate the proper procedures used in correctly using the compound
light microscope.
Determine the total magnification of the microscope.
Explain how to properly handle the microscope.
Describe changes in the field of view and available light when going from low
to high power using the compound light microscope
Explain why objects must be centered in the field of view before going from
low to high power using the compound light microscope.
Explain how to increase the amount of light when going from low to high
power using the compound light microscope.
Explain the proper procedure for focusing under low and high power using
the compound light microscope.
Materials
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Compound microscope
Beginners Set of prepared slides-letter “e”, …
Pencil
Procedures
I. Microscope Handling
1. Carry the microscope with both hands --- one on the arm and the other
under the base of the microscope.
2. One person from each group will now go over to the microscope storage area
and properly transport one microscope to your working area.
3. The other person in the group will pick up prepared slide set.
4. Remove the dust cover (if scope has one) and store it properly. Plug in the
scope. Do not turn it on until group has materials ready and procedures read.
5. Examine the microscope and give the function of each of the parts
listed on the right side of the diagram.
Biology
Hammerstedt
Name:_________________________________
Period_____
Date_________________
http://www.ekcsk12.org/faculty/jbuckley/lelab/microscopeuselab.htm
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Names of parts and their functions (place these on a sheet attached to this
report)#13 the inclination joint
Part II. Viewing of the letter "e”.
1. Turn on the microscope and place the slide on the stage;
making sure the "e" is facing the normal reading position (see
the figure above). Using the course focus and low power, move the
body tube down until the "e" can be seen clearly. Draw what you see
in the space below.
______________X
Biology
Hammerstedt
Name:_________________________________
Period_____
Date_________________
2. Describe the relationship between what you see through the eyepiece
and what you see on the stage. How does “e” appear through the
eyepiece compared to how it looks on the stage?
___________the “e”
_________________
appears upside down and backwards
3. Looking through the eyepiece, move the slide to the right in an upward
direction while on the stage. Do this carefully. What direction does the
image move?
___________left
and toward me (down)_________________________
4. Now, move it to the down and to the left side of the stage. What direction
does the image move?
__________up “away” & to the right____________
5. Re-center the slide, the “e” and change the scope to high power. You will
notice the "e" is out of focus. Do Not touch the coarse focus knob, instead
use the fine focus to resolve the picture. Draw the image you see of the
letter e (or part of it) on high power. If you are having trouble with this and
your microscope has a “medium power” power objective lens, observe this
before high power.
__________X
6.
Biology
Locate the diaphragm under the stage. Move it and record the changes
in light intensity as you do so.
Hammerstedt
Name:_________________________________
Period_____
Date_________________
_________larger
opening high intensity (bright) smaller opening
offers more contrast “shadow”___________
This portion of the lab may be completed with a partner!!!! Only one
sheet needs to be handed in!!!!!
III. Determining Total Magnification:
1. Locate the numbers on the eyepiece and the low power objective and fill in
the blanks below.
Eyepiece
magnification
_____10X______
2.
Objective
Total Magnification
magnification =
_____________X
____4X_____
Do the same for the high power objective.
Eyepiece
magnification
______10X______
3.
(X)
(X)
Objective
Total
magnification
=
Magnification
____10X or
_____________X
40X___
Write out the rule for determining total magnification of a
compound microscope.
______eye piece lens mag multiplied by objective lens =
total mag____
4. Remove the slide and clean it up. Turn off the microscope and wind up
the wire so it resembles its original position. Place the low power objective in
place and lower the body tube. Cover the scope with the dust cover. Place
the scope back in its original space in the cabinet.
Biology
Hammerstedt
Name:_________________________________
Period_____
Date_________________
Conclusion Questions:
1.
State two procedures which should be used when properly handling a light
microscope.
“open” & “close” activity with low power
objective facing stage; when carrying hold base
with one hand and arm with the other; do not
leave near edge of counter/desk top; do not pull
cord to unplug, hold the plug “head”
2.
Explain why the light microscope is also called the compound microscope.
The light microscope usually has two lenses
(multiplies or “compounds” magnification).
3.
Images observed under the light microscope are reversed and
inverted. Explain what this means. (How might you describe it?)
Compared to position of object on the slide on
the stage it appears upside down (inverted) and
backward or facing opposite direction (reversed).
4.
Why must the specimen must be centered in the field of view on low
power before going to high power.
If specimen is not centered in the field of view it
may not be visible when the higher power
objective is used as the field of view becomes
smaller as the magnification increases
5.
Biology
A microscope has a 20 X ocular (eyepiece) and two objectives of 10 X
Hammerstedt
Name:_________________________________
Period_____
Date_________________
and 43 X respectively: REMEMBER TO PUT AN “X” TO THE RIGHT OF YOU
VALUE ANSWER.
a.)
Calculate the low power magnification of this microscope.
Show your formula and all work.
eye X (x) lp obj X
b.)
20X (x) 10X = 200X total mag @ lp
Calculate the high power magnification of this microscope.
Show your formula and all work.
eyeX (x) hp obj X = total mag
20X (x) 43X = 860X total mag @ hp
7.
Describe the changes in the field of view and the amount of available light when
going from low to high power using the compound microscope.
The size of the field of view decreases by the dividend
of the ratio between hp & lp; the field of view gets
small
1.
2.
3.
4.
5.
6.
Biology
Eye piece (ocular) lens – lens through which the
eye views image
Body tube-supports lenses
Fine adjustment knob-used to focus high power
objectives for better resolution
Revolving nosepiece-supports lenses; allows
adjustment of magnification
High power objective- holds higher power
magnification lens
Low power objective-holds lower power
magnification lens
Hammerstedt
Name:_________________________________
7.
8.
9.
10.
11.
12.
13.
Biology
Period_____
Date_________________
Diagphragm-controls amount of light traveling
through stage opening to illuminate image/object
Mirror/light source-directs light through stage
opening
Base-support/balance microscope
Coarse adjustment knob-used to focus at lower
magnification (powered) objectives
Arm-supports the body tube
Stage clips-secures the slide for viewing
Inclination joint-can be adjusted to provide
more comfortable viewing angle on some
microscopes for prepared slides (do not need to
know)
Hammerstedt