Microscopes Biology 2010-2011

Lecture Notes When carrying any microscope, always carry it by the BASE and the ARM. There are two types of microscopes we will be using in this classroom. One is the COMPOUND LIGHT microscope which we will be using to see through objects (transparent). Biologists use this microscope to look into cells. The other is the STEREOMICROSCOPE which we will be using to see the surface details of objects because you cannot see through some objects (opaque). Biologists use this type of microscope during dissections.

The first lens used in any microscope is the lens in the EYEPIECE. This lens usually magnifies the object 10 times its actual size. The other lenses are called OBJECTIVES. The shortest one is used to find the object we wish to magnify (scanning lens). The middle lens is called the LOW - power lens. The longest lens is called the HIGH - power lens. There are two ways to focus on an object. The first is the COARSE adjustment. This can be used while using the scanning lense only. The second is the FINE adjustment. This knob ONLY must be used when using the low and high-powered lens.

Compound Light Microscope Microscope used to see transparent (see through) objects like cells and water. Eye piece Coarse adjustment Body tube Fine adjustment Revolving nose piece arm Scanning objective lens Stage clip High power objective lens Stage Mirror/light source Diaphragm Base

Microscope used to magnify opaque (not see through) objects. Stereomicroscope Microscope used to magnify opaque (not see through) objects. Eye piece Arm Objective lens housing Coarse adjustment Stage clips Stage Stage plate

Function of Microscope Parts Textbook Page 1054 Eyepiece Magnifies the image; usually 10x Body Tube Maintains correct distance between eyepiece and objectives Arm Supports the body tube; used to carry microscope Stage Supports a slide that contains the viewed specimen Coarse Adjustment Moves the stage up and down in large increments to allow gross positioning and focusing of the objective lens; use with scanning lens only Fine Adjustment Moves the stage slightly to bring the image into sharp focus; use with low and high power objectives Light Source (lamp or mirror) Provides light for viewing the image; shines light through object in compound light microscope Revolving Nosepiece Holds the objectives and can be turned to change from one objective to another Scanning Lens lowest power lens (shortest) used first to find objects Low-Power Objective Further magnifies image; usually 10x High-Power Objective Further magnifies image; usually 40x Diaphragm Located under the stage, controls the amount of light allowed to pass through the object Base Supports the microscope; used to carry microscope

Magnification Magnification is the measure of how much larger the object appears through the microscope than it actually is. For example if you are looking at leaf using a stereomicroscope with 3x magnification, the parts of the leaf will appear 3 times larger than they actually are. Magnification can be determined by multiplying the magnification of each lens used to see the object. 10x X 4x = 40x magnification magnification total of eyepiece lens of objective magnification Complete the chart below to calculate the total magnification of an object. Eyepiece Lens Objective Lens Total Magnification 15x 10x 20x 40x Which combination of lenses would allow you to see the object with greatest magnification? ____________ 2. Which combination of lenses would allow you to see the largest area of the specimen? ________________ Field of View – the amount of an object you can see while looking into the microscope.

Demonstration Wet Mount & Staining

MICROSCOPE RULES MICROSCOPES SHOULD BE PUSHED BACK AWAY FROM THE EDGE OF THE TABLE. ALWAYS BEGIN AND END A SLIDE WITH THE SCANNING LENS! WHEN FINISHED WITH A SLIDE, ALWAYS CLEAN THE SLIDE AND COVER SLIP WITH FRESH WATER AND WIPE DRY WITH A PAPER TOWEL. CLEAN LENSES WITH LENS PAPER ONLY! REPORT ANY BROKEN MATERIALS TO TEACHER IMMEDIATELY.