Microscope - PowerPoint

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					    The
Microscope
             The Microscope
► Improvements in the microscope and
  development of related biological techniques made
  our present knowledge of cell structures and
  functions possible.
► The compound light microscope is the major
  instrument for the study of cells. It will be
  used in the laboratory and can provide
  magnification up to 500X, depending on the
  magnification of the ocular and the objective.
► Although   some compound light microscopes
  can provide a magnification of 2000X, there
  is a limitation to the magnification, due to
  the resolving power of the lens.
► Therefore, the compound light microscope
  is primarily useful for viewing large cell
  organelles, such as nuclei and
  chloroplasts.
 The compound light microscope
    has 2 lens combinations:

A. The objective lens which forms a
   magnified image of the specimen.
B. The ocular lens or eyepiece lens,
   which further magnifies the image.
   The specimen used on the
compound light microscope must
        be transparent.

WHY?
There are a number key parts of the
compound light microscope and the
  functions of these parts are as
              follows:
1.   Ocular lens (eyepiece): used to “look
     through” and generally magnifies at 10X.
2.   Objective lenses: found closest to the
     object to be studied. It provides the rest
     of the magnification of the compound light
     microscope and generally magnifies at 4X,
     10X, 40X.
              Magnification
► Magnification  of a compound microscope is
  the product of the power of the objective
  multiplied by the power of the ocular.
► Example:
     objective = 40X
     Ocular = 10X
What is the total magnification?
                      400X
            Resolving Power
► Useful magnification is limited by its
  resolving power.
► The resolving power is the ability to
  separate 2 objects close together.
► The properties of light place an upper limit
  on the resolving power of any light
  microscope.
             3. Stage

►The  flat surface (platform) on
 which the specimen or slide to be
 studied is placed.
          4. Stage Clips

►Used  to hold the specimen or slide
 in place.
        5. Coarse Adjustment:
► The  larger knob
► Used primarily to focus under low power (up
  to 100X) only!
► It causes large movement of focusing.
► Course adjustment must never be used
  when the high power objective is in
  position.
► If you use this under high power, you will
  break the slide!!!!
        6. Fine Adjustment:
►The  smaller knob
►Used for focusing under high power
 and final focusing under low power.
►It causes small movement for focusing.
►The fine adjustment knob should never
 be turned more than one half turn in
 either direction.
             7. Light Source:
► Provides light
► Light must pass through the object to be
  studied in order for an image to be viewed
  in the objective lens.
► In some microscopes, a mirror is present
  and directs the light from a horizontal
  surface up through the diaphragm and the
  specimen.
           8. Diaphragm:
►It is found under the stage.
►Controls the amount of light passing
 through the specimen and into the
 objective lens.
►Smaller openings of the diaphragm
 increase the resolution or the amount
 of detail in the image.
              9. Arm

►Holds the tube and the stage
►Used to carry the instrument
              10. Base:

►Supports   the instrument
           11. Body Tube

►Hold   the lenses
           12. Nosepiece:

►Rotates  to change the objective
 lens from one power to another.

				
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posted:10/4/2012
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