I. IntroductionA microscope is an instrument use to see objects that are microscopic or too

small for the naked eye to see. This report discusses the parts, importance, features and uses of a compound microscope to various experiments. This report presents the procedure for the experiment, the result and its analysis.

II. Objective:The objective of the experiment is to become familiar with the compound

microscope, its uses and its parts.

III. MaterialsCompound microscope, pencil, cut letter e, glass slide and coverslip.

IV. Procedure and Observations: A. Parts of the microscope

1. Eyepiece or ocular is the removable cylinder on top of the microscope. It contains one set of lenses, the magnifying power of which is indicated on top of the eyepiece. 2. Draw tube is the hollow cylinder where the eyepiece is placed.3. Body tube forms the body of the microscope. The ocular and the draw tube rest on the body of the tube.4. Revolving nosepiece is one that is attached to the base of the body tube.5. The revolving nosepiece has two or more small cylinders with magnifying lenses called the objectives.6. Low power objective (LPO) is the shorter of the two objectives. It contains a series of lenses which magnify an amount indicated on the side of the objective. Its magnification is between 10-15x. 7. High power objective (HPO) contains lenses which give greater magnification. Its magnification is between 45-50x.8. The microscope is focused by turning two knobs. The coarse adjustment knob consists of large knobs on the side.9. The fine adjustment knob is a pair of small knobs that is used for sharp focus after the object has been brought into view with the coarse adjustment knob. 10. The curved part of the microscope is the arm. When carrying a microscope, one hand should grasp the microscope by the arm and another hand supports the base. The base should always be held parallel to the floor. 11. The platform where slides are put for observation is called a stage. It has a circular opening which is called aperture that permits entry of light.12. The slide is held in place on the stage with a pair of stage clips. 13. Below the stage, you will find a lever which controls the amount of light passing through the stage. This is called diaphragm.

14. In the old model of a compound microscope you will see a two-sided mirror, one flat and one concave. The flat mirror is used to collect minimum light required while concave is used if more light is required. In the new model of a compound microscope, a bulb is used as light source. Brightness is adjusted using the knob beside it. 15. The portion of the microscope in contact with the table is the base.16. The body of the microscope is attached to the base by means of the inclination joint. This permits the tilting of the microscope.

V. Discussion

The laboratory activity started with a discussion of the history, importance, parts and functions of microscope. A microscope is a laboratory apparatus that is invented by Anton Von Leeuwenhoek and later modified by the Janssen brothers. It is used to magnify things that can’t be seen by naked eye being the reason why it is important in the study of life. In today’s world, microscope is widely used in the world of science especially in pharmacology, microsurgery or in general, medicine. As of now, there are various kinds of microscope, three of which are simple, compound and electron microscope. On the other hand, magnification is how many times an object is enlarged which is denoted by an “x”. A microscope can magnify things 10-500,000x depending on what microscope is used. Total magnification is computed by multiplying the ocular magnification by the magnification of the objective being used. In this particular exercise we used a compound microscope which is sometimes called a light microscope for the reason that is uses light from the sun or from a bulb as a source of illumination to see the object or specimen under the observation. It not only provides greater magnification but also greater resolution.

In the experiment proper, each group is given a cut letter “e”, a glass slide and a coverslip and is ordered to follow the instructions in the given hand out. In this experiment we used a compound microscope to help us answer the questions being asked. The group puts the cut letter “e” in the middle of the slide, placed a drop of water and covered it with a coverslip. The slide is put on the stage (see illustration 2) and held it at a certain position using a stage clip. The bulb of the microscope is turned on allowing it to illuminate the object. At first glance at the ocular using the scanner, there is a need to adjust the focus using both the coarse adjustment knob because all you can see is plain white and not the object itself. After using the scanner, we tried to use the LPO and HPO. In LPO, you will see a very detailed letter “e” that even traces of water and materials of the paper can be seen (see illustration IV). On the other hand, while using the HPO, we adjusted the focus using the fine adjustment knob but still we can’t see anything but light because HPO tends to super zoom the image.

The total magnification for scanner, LPO and HPO is 40x, 100x, and 400x respectively. The total magnification is computed by multiplying the ocular’s magnification which is 10x with the objectives respective magnification which is 4x, 10x and 40x.

As we move on with our experiment, we moved the slide to the right using the x-axis knob. We noticed that as we move the slide to the right direction, the image from the ocular moved in a directly opposite direction. After, we tried to move the slide to the left and the same thing happened; it moved oppositely. Lastly, we tried to move the slide forward and backward using the y-axis knob and just like what happened in the x-axis, it also moved in an opposite direction.

VI. Question

1. What is the magnification of the low power objective? High power objective?2. When do you use the concave mirror?3. To what direction did the letter e go under the microscope? Did the letter e moved to the right or to the left?4. What is the magnification of the letter e under low power? Under high power?5. Why is it that the compound microscope is called a light microscope?6. Why is the microscope important in the study of life?

VII. Illustration

I. This is the position of the cut letter “e” as we prepare the slide and after we put a drop of water.

II. This is the position of the cut letter “e” as we put it in the stage of the microscope.

III. This is the position of the cut letter “e” under the microscope even if we put it in a different position. Also, this can be seen using the scanner. IV. This is what cut letter “e” looks like under the LPO. You can see even see the material of the paper and some traces of water. In HPO,

e

e

there is no image that can be seen because of the very high magnification feature of the objective.

VIII. References

Microscope: From http://en.wikipedia.org/wiki/From Collier’s Encyclopedia. Copyright 1997 Newfield Publications, Inc. Vol. 6. p. 140-143

Compound microscope:From http://www.microscopehelp.com/thecompoundmicroscope.htmlFrom Collier’s Encyclopedia. Copyright 1997 Newfield Publications, Inc. Vol. 6. p. 140-143

Parts of a microscope: From http://www.microscope.com/compound-microscope-parts-t-7.html

Introduction to Zoology

Exercise no. 1: The Compound Microscope

Jonathan O. Chua June 22, 2011DVM 1-1 Dr. Noemi Diloy