microscopy

• How do you prepare the microscope slide?

  Cut an onion using a sharp knife and peel off a thin layer of onion epidermis from a piece of onion

  Place the onion epidermis onto a microscope slide in a single flat layer

  Add three drops of iodine solution

  Lower a cover slip at an angle onto the epidermis

  Place the slide on the stage of the microscope
• What are safety precautions in this experiment?

  Iodine solution - wear gloves and wash hands immediately if it comes into contact with skin. (could cause a rash or irritation)

  Sharp knife - cut on a chopping board and keep fingers away from the blade
• Why do we use a thin layer of onion epidermis?

  So that you can see individual cells under the microscope
• Why do we use iodine solution?

  To stain parts of the cell so they're more visible
• Why do we put the cover slip on the onion at an angle?

  To prevent air bubbles
• What is the equation for magnification?

  Magnification = size of image / size of real object
• What are the steps for the microscopy experiment?

  After the microscope slide is set up on the stage, turn the nosepiece to the lowest power objective lens.

  Use the coarse adjustment knob to raise the stage until almost touching the nosepiece.

  Look through the eyepiece and move the stage down until the image is in focus.

  Repeat this step for the other objective lenses and then turn the fine adjustment knob until the image is focused
• What are the usual magnifications for the objective lenses?

  4x, 10x, 40x