Microscope: General use
Name _____________________________________
1. Label the picture of the microscope. You are responsible for knowing the parts, and what they are for.
2. When holding the microscope, hold it by the arm, and put your other hand under the base.
3. Keep microscope at least 10 cm from the edge of the table.
4. If the microscope is too high to comfortably view objects, you can pull back on the arm while holding the
base, to angle it back to more easily look through the eyepiece.
5. Make sure the lenses are clean. Wipe the lenses with lens paper: all three objectives and the eyepiece.
6. Make sure the microscope is plugged in to turn on the light. Look through the lens with the low power
objective in place. Turn the diaphragm so that the most light comes through the stage. What number is this
on the diaphragm? ______. The circle of light you see is called the field of view.
7. Turn the coarse focus knob so that the low-power objective is as far down as it will go. Put a prepared slide
on the stage under the clips. Slowly turn the coarse focus knob up until the specimen comes into focus.
8. Always find an object on low power first, because it has the largest field of view. Move the specimen to
the left, which way does it appear to be moving when looking through the microscope?___________________
9. Move the slide away from you. Which way does the specimen appear to be moving?_________________
10. Draw the specimen under low power. Then, carefully turn the nosepiece to medium power and draw
again.
low power
medium power
11. When you switch from low power to medium or from medium to high, you should always have the object
you are looking at centered and focused. Otherwise you will lose sight of the object when going to the higher
power.
12. When you have finished drawing the specimen under medium power, turn the nosepiece to high power.
Use only the fine focus when you are on high power, or you may damage the lens or the slide.
13. Switch back to low power, remove the slide, and put it away.
14. The microscope’s magnification is determined by the power of the eyepiece and the power of the
objective. What is the power of the eyepiece? _________ Low power objective? _________ Medium?
_________ High? ________
15. To determine the total level of magnification, simply multiply the power of the eyepiece by the power of
the objective you are using. Low power magnification =_____________ Medium= ____________ High =
____________
Note: The power of the objectives may be different when using different
microscopes.
Microscope: Making slides
1. Now that you know the basic use of the microscope, it is time to learn how to make slides for use with the
microscope.
2. Get a blank slide and a coverslip. Put a drop of water on the slide, put a hair, small piece of paper, or small
piece of grass in the water on the slide, and cover with a coverslip to hold it in place.
3. Look at the specimen under the microscope, using the proper procedures as performed above: start on
low power.
4. When you are done looking at the slide, clean it off with a paper towel and put the slide and coverslip
away.
Microscope: Estimating sizes
1. Put a millimeter ruler on the microscope stage. Microscope should be on low power.
2. Count the number of millimeters across the field of view. Make sure that one line of the ruler is on the
edge of the field of view (see below). Record that number _____________________mm (low power f.o.v.)
I I I I I I
I I
Right ! Line is on edge of f.o.v.
I I I I I I
I I
Wrong! Line is not on edge of f.o.v.
3. This gives you the diameter of the low power f.o.v., but not the medium or the high powered field of
views.
4. Let’s use math to figure out the medium powered field of view.
1. Divide the low power magnification by the medium power magnification.
(low power magnification / medium power magnification) = _____________
--this gives you a ratio that you can use to find the medium power f.o.v.
2. Multiply that ratio by the measurement you got when you measured the low power f.o.v. with the
ruler.
(ratio from step 1) X (low power f.o.v.) = ______________ mm (medium power f.o.v.)
--This gives you the field of view of the medium powered objective. Notice that it is smaller than the low
powered field of view. So, as you increase magnification, the field of view decreases. In other words, it is
inversely proportional.
5. Use the same process to find the high powered field of view. (Substitute “high power” for “medium
power” in the steps above).
1. Divide the low power magnification by the high power magnification.
(low power magnification / high power magnification) = _____________
--this gives you a ratio that you can use to find the high power f.o.v.
2. Multiply that ratio by the measurement you got when you measured the low power f.o.v. with the
ruler.
(ratio from step 1) X (low power f.o.v.) = ______________ mm (High power field of view)
F.O.V Low __________________, medium ___________________, high __________________
6. Once you know the diameter of the field of view, you can estimate sizes by taking the diameter and
dividing it by the number of organisms that would fit across the f.o.v.
7. Estimate the sizes of the paramecium, volvox, and euglena using this technique. Record your estimates
below.
Paramecium _____________mm Volvox_____________mm Euglena _____________mm