Using Microscopes
Part 2
Stereomicroscopes
- Carefully remove the stereomicroscope (two eyepieces) from under your lab table. Always keep the cover on the microscope when it is not in use.
- What is the magnification of the lowest power?______Highest power?______
- How does the working distance affect the size of objects that can be viewed under the stereomicroscope compared to the compound microscope?
- Lay your hand on the stage of the stereomicroscope. Focus on the back of your hand and draw exactly what you see in color.
Specimen______
Magnification______
- Compare the movement of your hand seen through the eyepieces to the direction you moved your hand. Is it the same as in a compound microscope? Explain.
- Compound light microscopes work by having light pass through the objects to be viewed. However, not all objects are translucent (see through). Some objects are opaque (not see through); light cannot pass through them. Make wet mounts of an onion skin with iodine stain and a small piece of leaf. Observe both under low power.
- How does your view of onion skin compare to your view of the Leaf?
- If an opaque object is viewed through a compound light microscope, what will you see?
- Place a leaf under the stereomicroscope. Focus on the highest power and draw exactly what you see in color.
Specimen______
Magnification______
- How come you can see the leaf with a stereomicroscope, but not with a compound light microscope?
- Place either a coin or paper money under the stereomicroscope and focus on the eye of the person on the money. Draw exactly what you see in color.
Specimen______
Magnification______
Review of Microscopes
- Under which power, high or low, is the largest field of view?
- What happens to the field of view when you switch from low power to high power?
- Why do objects look three-dimensional under a stereomicroscope but not under a compound microscope?
- If a microorganism were swimming from right to left across your field of view under a compound light microscope, which way would you move the microscope slide to keep it in view? Why?
- If the same microorganism as above were swimming from right to left across your field of view under a stereomicroscope, which way would you mover the microscope slide to keep it in view? Why?
- Take a sample of pond water and make a wet mount. Look for moving organisms under high power. Find two different kinds of microorganisms and draw them in color.
If the microorganisms are moving too fast, add a drop of slowing solution to your sample.
Choose a minimum of any THREE extra specimens to examine. Make sure you write down the name of the specimen and the magnification used for best viewing. Below you will find a list of ideas, but anything that has microscopic structure will work.
Possible specimens:
- Cheek cell stained with methylene blue
- Scrape the inside of your cheek with a tooth pick
- Rub the goo you collect on a slide and mix with a drop of methylene blue
- Yeast cell stained with methylene blue
- Onion skin stained with iodine
- Cork slice
- Pollen grain
- Aquarium rock water
Anything else?