Microscope Lab
Do Now: Pick up lab and preread the
whole lab, answer pre-lab questions when
finished reading. Not before, after!
Set up your Cornell Notes As
Follows (skip lines……):
I. Safety
 II. Magnification
 III. Preparing Wet Mount
 IV. Focusing
 V. Electron Microscopes
 Define: resolving power, depth of view
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Compound Light Microscope
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Always carry with 2 hands
 Arm
and base
Place away from edge of table
 Always start with
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stage all the way down
 Light off
 Lowest power
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Always return the microscope to this
position when finished
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Eyepiece
Course Focus
Fine Focus
Scanning Obj
Arm
Power
Body Tube
Nose piece
High Power
Low Power
Clips
Stage
Diaphragm
Light
Base
Magnification
• Eyepiece
– What you look through
– May have pointer inside
– 10x
• Rotating nosepiece has 3
objectives
– Scanning (short and red) 4x
– Low (medium and yellow) 10x
– High (long and blue) 40 x
Total Magnification =
Eyepiece X objective
• Eyepiece
• 10x
• Scanning 4x = 40x total
• Low 10x = 100x total
• High 40x = 400x total
Controlling light
• First plug in and turn on the
light.
• Under the stage is a rotating
disc that turns and clicks
• It may have numbers on it
• Turning the diaphragm (disc)
controls the amount of light
Slide #1
• Prepared slide of crossed threads
• Place slide on stage and secure
• Use scanning objective and try to center the
crossed threads then focus
– Use course focus (large knob) first
– Fine focus (small knob) second
– Which way does the slide move if you push it left? Push
right?
– What affect does changing the diaphragm have on the
image?
• Change to low power
– Notice any change?
– Draw
• Change to high power
– USE ONLY FINE FOCUS!
– Course focus can press into slide and crack
the glass, squish specimen, and damage the
objective.
– It may take time to focus correctly - practice
– How does the view of the image change?
– Draw
NO SQUISH THE SLIDE!!!!!!
The Wonderful Letter e
• Preparing a wet-mount
– Cut out a lower case letter e
– Place on slide
– Carefully add water drop
– Try to keep the e looking like this… e
– Carefully place cover slip on letter
• Place slide on
microscope and secure
• Start with scanning
objective - center and
focus. See any thing
unusual?
• Change to low power
and draw
• Change to high power
and draw
Depth of View
• Notice that as you increase
magnification you see more detail of
less of the image.
• You also see layer of the image that
you can focus through
• More of less
Resolving Power
• A measure of the clarity of an image.
Closure
• Complete post lab questions
• Turn in lab
Electron Microscope
• Scanning or SEM
• Uses electrons bounced off
the surface of the
specimen
• Transmission or TEM
• Electrons through the
specimen
• Live specimens cannot be
used
Electron Microscope
(2 kinds)
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Transmission Electron
Microscope
TEMElectrons go
Through the
Specimen
(non living
Specimens
Only)
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Scanning Electron
Microscope
SEM –
Uses electrons
Bounced off the
Surface of the
Specimen
(non living
Specimens only)