Transcript Microscopy - Ms. Pass's Biology Web Page

Microscopy
Types of Microscopes:
1. Compound Light Microscope (what we
use most often)
2. Stereoscopes – also known as dissecting
scopes
3. Electron Microscopes
Parts of the Microscope
Arm
Parts of the Microscope
Diaphragm
Light Source
Parts of the Microscope
Stage
Stage Clips
Parts of the Microscope
Revolving
Nosepiece
Objective
Lenses
Parts of the Microscope
Ocular Lens
Parts of the Microscope
Coarse adjustment knob
Used only when low power objective is used!!
Parts of the Microscope
Fine adjustment knob
Important Vocabulary :
magnification \mag-ne-fe-'ka-shen\ n 1.
apparent enlargement of an object 2.
the ratio of image size to actual size
A magnification of "100x" means
that the image is 100 times bigger
than the actual object.
resolution \rez-e-loo-shen\ n 1. clarity,
sharpness 2. the ability of a
microscope to show two very close
points separately
Magnification
ocular power = 10x
low power objective = 20x
high power objective = 50x
a) What is the highest magnification you
could get using this microscope ?
500x
Ocular x high power = 10 x 50 = 500. (We
can only use 2 lenses at a time, not all
three.)
b) If the diameter of the low power field is 2
mm, what is the diameter of the high
power field of view in mm ?
.8 mm
The ratio of low to high power is 20/50. So at high
power you will see 2/5 of the low power field of
view (2 mm). 2/5 x 2 = 4/5 = .8 mm
c) in micrometers ? 800 micrometers
To convert mm to micrometers, move the decimal 3
places to the right (multiply by 1000). .8 mm x 1000
= 800 micrometers
d) If 10 cells can fit end to end in the low power field
of view, how many of those cells would you see
under high power ? 4 cells.
We can answer this question the same way we go
about "b" above. At high power we would see 2/5
of the low field. 2/5 x 10 cells = 4 cells would be
seen under high power.
Carrying a Microscope
Steps to Use:
1. Rotate the low power objective into place and make sure the
stage is all the way down.
2. Place slide on stage making sure object to be viewed is
centered over the hole in the stage. Use the stage clips to
hold the slide in place.
3. Turn light on.
4. Focus first with the coarse adjustment knob. Once in focus on
low power, turn the nosepiece until the next higher lens is in
place.
5. Use FINE adjustment knob ONLY and focus the object.
Recording what you see:
Include:
1.
Figure #: and Title
2.
Labeled drawing of the field of view. Label on the right using straight lines which
should never cross.
3.
Common and scientific name of organism.
4.
Magnification you were viewing when you drew the organism: ocular X objective
Making a wet
mount:
Wet Mounts:
Poorly
Done:
Nicely
Done:
Remember:
1. If you are seeing perfectly round, clear circles then you
just may be looking at air bubbles. Check your slide and
try again.
2. Microscopes must always be properly put away.
3. Slides and cover-slips should be washed, dried, and
returned to their proper place.