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What is a Microscope?

A microscope is an optical instrument that allows you to see objects magnified.    Some microscopes are so strong that you can see things that the human eye can't see alone like cells, ash, and snowflakes.  A simple microscope is one that uses only one lens to magnify, such as a magnifying glass.   A compound microscope uses two or more lenses to magnify the specimen.   The microscope you have at school probably uses a combination of lenses to magnify, but for their research some scientists have microscopes that use electronics to magnify.    They are called electron microscopes.   There are many other types of microscopes including ones that use x-rays, gases, and lasers.   Microscopes allow us to see what makes people sick and how organisms work.   We can study the make up of rocks, and even fluids. For example, we can see exactly what is in a glass of drinking water.   

Parts of a microscope

1) Eyepiece:

The Eyepiece is the top part of the microscope; it is the lens you look through to see your specimen.    

2) Arm:

The Arm:  Itís the large metal band attaching the base to the lens and eyepiece.  When you carry a microscope, use one hand to hold the Arm,  and the place the other under the base 

3) Fine Adjustment Knob:

The Fine Adjustment Knob:  Itís the smaller round knob on the side of the microscope used to fine-tune the focus of your specimen after using the coarse adjustment knob.   

4) Coarse Adjustment Knob:

The Coarse Adjustment Knob:  Of the two knobs on the side of a microscope, it is the largest.   It is used to focus on the specimen; it may move either the stage or the upper part of the microscope (in a relative up and down motion).   Always focus with the coarse knob first. 

5) Objective Lenses

Objective lenses:  Most microscopes have 2, 3, or more lenses that magnify at different powers.   Always start with the lowest power and work your way up to the strongest when examining a specimen.    The shortest lens is usually the lowest power.   

6) Stage:

The Stage:  Itís where the sample or specimen is placed for examination. 

7)  Iris Diaphragm:

The Iris Diaphragm:  Itís what allows you to control the amount of light on the specimen that comes through the stage. (Through the Aperture) 

8)  Light Source:

The Light Source:   It can be a bulb or a mirror, and is usually found near the base of the microscope shining up through the stage.   

9 Aperture:

The Aperture:  Itís the hole in the stage that allows light through for better viewing of the specimen.   


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