The Compound Light Microscope

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The Compound Light Microscope

• Section 1-4and Appendix D

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What is a compound light microscope?

• Mechanism for enlarging
• an image

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How Does a Microscope Work?
the specimen
the image
the eye
A lens is a bi-convex diskthat bends light
The bent rays produce an image
Each lens magnifies the image, increasing its
overall size
The farther the light rays are bent, the larger
the image appears
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Evolution of the microscope
Choice of lens magnification
2 set lenses
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How Does a Microscope Work?
the specimen
the image
the eye
As the light rays are spread farther
apart, the clarity or resolution of the image
decreases
Resolving power (resolution) A measure of the
ability of lens or optical system to form
separate and distinct images of two objects
Light microscopes are limited in their
magnification by their resolving power!
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Resolution vs. Magnification
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How Does a Microscope Work?
the specimen
the image
the eye
The image is always seen upside down and
backwards from its actual position
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Magnification

• The two lenses are called
• Ocular (eyepiece)
• Objective lens
• The ocular has a magnification of 10x
• The magnification of the objective lenses vary
  and are marked on the lens
• To find the magnification, multiply the
  magnification of the eyepiece lens by
  themagnification of the objective lens.

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Figuring Magnification

• Total magnification
• (Eyepiece) X (Objective)
• Ex TM 10X x 40X

400X
100X
1000X
30X
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Total Magnification
Elodea 40x
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Total Magnification
Elodea 100x
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Total Magnification
Elodea 400x
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Lets Review!
Eyepiece
Body tube
Ocular
Nosepiece
Arm
Low power
Medium power
Stage
High power
13.
Course adjustment
Stage clips
Diaphragm
14.
Fine adjustment
Light source
Base
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The Parts of the Microscope and Their Function
MagnificationPart you lookthrough
Maintains proper distance between lenses
Hold objectives- rotates to change magnification
Supports body tube
Various magnification
Supports slide
Holds slide in place
Rapid focusof image
Regulates amount of light
Sharpens theimage
Reflects light towards eyepiece
Supports microscope
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Proper Procedures

• Carry the microscope with one hand under the base
  while grasping the arm with the other hand
• Place microscope 10cm from the edge of the table
• Be careful of the cord when moving around the lab
  tables!!

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Proper Procedures

• 3. Rotate the nosepiece to obtain the proper
  objective lens (always start with low power!)
• Make sure the lens clicks into place!!

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Proper Procedures

• 4. Place the slide on the stage, center
  specimen over stage opening (aperture)

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Proper Procedures

• 5. Look through the eyepiece and switch on the
  lamp
• This is your field of view!

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Proper Procedures

• 6. Locate specimen on low power using coarse
  adjustmentknob

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Proper Procedures

• 7. Carefully switch to medium or high powerDO
  NOT move the stage and nosepieceapart!!
• 8. Focus image with fine adjustment

Avoid damaging slide! NEVER use course
adjustment with high power!
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Proper Procedures

• 9. Adjust the amount of light with the
  diaphragm if needed

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Storing the Microscope
Four steps prepare the microscope for storage

• the 10X or low objective is in place
• the stage is all the way down to itslowest
  position
• the power is off
• the cord is wrapped around the base

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Microscope Self Quiz
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S. Harris Biology Cartoons