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How to Use a Microscope in Biology

How to Use a Microscope in Biology. Many biological objects can be very small therefore a microscope is often used to view them. . There are 2 types of microscopes. Light microscopes – light is passed through one or more lenses to produce an enlarged image

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How to Use a Microscope in Biology

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  1. How to Use a Microscope in Biology

  2. Many biological objects can be very small therefore a microscope is often used to view them.

  3. There are 2 types of microscopes • Light microscopes– light is passed through one or more lenses to produce an enlarged image • Electron microscopes– an image of a specimen is formed using a beam of electrons rather than light

  4. Light vs. Electron Microscope Red Blood Cells Light Microscope (top) Electron Microscope (right)

  5. Electron Microscopes • Transmission Electron Microscope (TEM) • Scanning Electron Microscope (SEM)

  6. Micrographs are images produced by a microscope • *These often include the magnification value of the image. • Magnification – is the ability to make an image appear larger than its actual size • Resolution – is a measure of the clarity of an image

  7. 2 Types of Light Microscopes • We have two kinds of light microscopes available in the lab. • Light microscopes use light rays that are magnified and focused by means of lenses. • The binocular dissecting microscope is designed to study entire objects in three dimensions at low magnification.

  8. Fly Wing with a dissecting microscope

  9. The Compound Light Microscopeis used for examining small or thinly sliced sections of objects under magnification that is higher than that of the dissecting light microscope. • Illumination is from below, and the light passes through clear sections but does not pass through opaque sections. • To improve contrast, stains or dyes are used that bind to cellular structures and absorb light.

  10. Parts of the Compound Light Microscope • Identify the following parts on your microscope and answer the questions below • 1. Eyepiece (ocular lens): Topmost series of lenses through which an object is viewed. What is the magnifying power of the ocular lens on your microscope? ______

  11. 2. Body tube: holds nosepiece at one end and eyepiece at the other end; conducts light rays • 3. Arm: Supports upper parts and provides carrying handle • 4. Revolving Nosepiece: houses all of the objective lenses

  12. 5. Objectives (objective lenses): • Low-power objective: Holds 4x lens used to view the object in greater detail. What is the total magnifying power of this lens on your microscope? _______ • Medium-power: Holds 10x lens used to view the object in greater detail. What is the total magnifying power of this lens on your microscope? _______

  13. High-power objective: Holds 40x lens used to view the object in even greater detail. What is the magnifying power of this lens on your microscopes? _______

  14. 6. Coarse-adjustment knob: Knob used to bring object into approximate focus; used only with low-power objective • 7. Fine-adjustment knob: Knob used to bring object into final focus • 8. Diaphragm: Controls amount of illumination used to view the object

  15. 9. Light source: An attached lamp that directs a beam of light up through the object • 10. Base: The flat surface of the microscope that rests on the table • 11. Stage: Holds and supports microscope slides

  16. Rules for Microscope Use • Always start with the lowest power objective and it should be in position at the beginning and end of microscope use • Only use lens paper for cleaning lenses • Never tilt the microscope when viewing a slide • Keep the stage clean and dry at all times • Do not remove parts of the microscope • Report any problems to your teacher immediately

  17. Tips for Microscope Observations • Always sketch observations in pencil • Label all micrographs and include total magnification used • Use color pencils when micrographs are sketched if needed

  18. Microscope Measurement • To get total magnification, the eyepiece magnification and the objective magnification must be multiplied together. • For example: Eyepiece magnification is 10x and the low-power objective lens magnifies 10x, the total magnification would be ? • As magnification increase, the field of view of a microscope decreases proportionately

  19. Electron Micrographs Can you guess what these are?

  20. FLEA

  21. HAIR

  22. SPIDER

  23. FEATHER

  24. POLLEN

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