DB014 Pre-Lab Module
EXPERIMENT 1 : BASIC TECHNIQUES IN MICROSCOPY
Course Learning Outcome:
Solve basic problems related to cells, biomolecules, inheritance, genetics and biological
development.
(C3, PLO 4, CTPS1, MQF LOD 6)
Learning Outcomes:
At the end of this lesson, students should be able to:
i.
To handle microscope properly
ii.
To obtain accurate images.
iii.
To calculate the actual magnification.
Student Learning Time:
Face-to-face
Non face-to-face
1 hour
1 hour
Direction: Read over the lab manual and then answer the following question.
Introduction
1.
Use the words list to help you label the parts of microscope and its function as shown in
FIGURE 1.
No
Part of Microscope
Function
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
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DB014 Pre-Lab Module
e
f
a
g
h
b
i
c
j
d
k
l
FIGURE 1
arm
revolving nosepiece
manipulator knobs
coarse adjustment knob
2.
iris diaphragm
fine Adjustment Knob
light Source
base
objective Lenses
ocular Lens
stage
stage Clips
For questions i to vii, choose the correct answer from the following list:
A. Scanning objective lens (4x)
B. Low-power objective lens (10x)
C. High-power objective lens (40x)
D. Oil immersion objective lens (100x)
i. Which is the shortest objective lens? (__)
ii. Which objective lens should you use when you begin to focus a specimen? (__)
iii. Which objective lens should be in position before you store a microscope?
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DB014 Pre-Lab Module
iv. Which objective lens will deliver the highest amount of light? (__)
v. Which objective lens requires immersion oil to fill up the space between the
specimen and the lens? (__)
vi. Which objective lens will still remain in focus when placed at the longest working
distance from the specimen? (__)
vii. Normally there are 3-4 objective lenses mounted on the nosepiece, and these can
be rotated and changed as you require. This lens is found at the top of the
microscope. It normally has a magnification power of 10x or 15x. Actual
magnification power is obtained by multiplying magnification power of the
objective lens with the magnification power of ocular lens.
When using an ocular lens with 10x magnification power, which objective lens
should be used to obtain the following actual magnification?
a. 100 times of its diameter
b. 1000 times of its diameter
Experiment
1.
Image formed under microscope is virtual, inverted and magnified. Draw the image of
letter L which is observed under microscope.
L
‘L’ seen by naked eye
2.
‘L’ image
Complete the drawing of the images below which was observed using different objective
lenses.
4x objective lens
10x objective lens
40x objective lens
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DB014 Pre-Lab Module
3.
Calculate the actual magnification for the above images.
Magnification
power of ocular lens
Actual magnification
Magnification power of objective lens
4x
10x
40x
10x
4.
Tick ‘√’ to show the correct way to store the microscope when you have finished using
the microscope.
STEPS
PROCEDURE
Turn off the light switch or close down the iris diaphragm to reduce the amount
of light to a minimum and then switch off the power.
Check that you have not left a slide on the stage.
Check that the high objective lens (40x) is placed back in position over the
centre of the stage.
Check that the stage is clean without any trace of water or dust on it. If there is
any water on the stage, wipe it off with dry tissue. If it is oil, wipe it off with
dry tissue with some alcohol.
Hold the microscope with only one hand, when you want to store the
microscope.
If you use oil immersion objective lens, gently wipe it with clean lens tissue.
Tie up the power chord below the body arm.
Ensure the slide clips are placed on the stage and they are not protruding.
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