Add. Prac. 6- Microscopy

• What is the purpose of using an eyepiece graticule?

  The eyepiece graticule is within the eyepiece lens. It is used to measure the size of the specimen you are viewing under the microscope.
• What is the purpose of the stage micrometer?

  To calibrate the eyepiece graticule
• How do you calibrate the eyepiece graticule?

  1. Change the microscope to the lowest objective lens
  2. Line up the stage micrometer with graticule by focusing the microscope using the coarse focus knob
  3. Count how many divisions of the graticule fit into one division of the micrometer
  4. Calculate how much one division of the eyepiece graticule is worth
  5. Repeat for medium and high power lenses
• What must you do each time you change the objective lens?

  Re-calibrate the eyepiece graticule
• How to calculate 1 graticule division?

  Number of micrometers / number of graticule divisions
• How to prepare a slide for viewing the leek cells under the microscope?

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  1. On the white and green area, place a thin layer of clear nail varnish and let it dry
  2. Once it has dried, place a piece of sticky tape over the nail varnish and peel it off (Don't touch the sticky side)
  3. Place tape on clean slide
• How do we create the biological drawing of the leek cells using the images viewed under the microscope?

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  1. Use the eyepiece graticule to measure the length of one cell and use this to draw the cell accurately
  2. Calculate the magnification
• What are the basic steps of this practical?

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  1. Calibrate eyepiece graticule
  2. Prepare and measure leek cells
  3. Biological drawings