microscopes 4th quarter 2008. microscopes magnifies objects (makes objects look bigger) help...

MICROSCOPES

4th Quarter

2008

MICROSCOPES

• MAGNIFIES OBJECTS (MAKES OBJECTS LOOK BIGGER)

• HELP SCIENTISTS STUDY OBJECTS & LIVING THINGS TOO SMALL TO SEE WITH THE NAKED EYE

• We use a compound light compound light microscopemicroscope

3 Types of Microscopes

• simple microscope has only 1 lens. compound microscope has 2 sets of lenses. It can magnify things 100 - 200 times larger than they really are.

• electron microscope can magnify objects up to 300,000 times. They do not use lenses, but use electrons to enlarge the image.

PARTS OF A MICROSCOPE

1. eyepiece• the lens of the microscope that you

look through2. course adjustment

• the large knob on the microscope that you turn to bring the object into COARSE focus

3. fine adjustment• the small knob on the microscope

that brings the image into SHARPEST focus

PARTS OF A MICROSCOPE

4. arm• the part of the microscope

supporting the body tube

5. body tube• the part that holds the eyepiece

and the objective lenses.

6. nosepiece • the part at the bottom of the body

tube that holds the objective lenses and allows them to be turned

7. -high power objective lens • the lens that magnifies the object

the greatest amount. (usually 40x)-Low power (scanner) objective lens

• the lens that magnifies the object the least amount (usually used to find the object; magnifies only 3 or 4 times)

-middle power objective lens • the lens that usually magnifies the

object more than the scanner lens, but less than the high power lens (usually 10x to 20x)

8. stage •the flat part below the objectives

lens where the slide is placed9. clip

•the part that holds the slide in place so it doesn’t move

10. diaphragm •the part that controls the amount

of light entering the field of view

11. light source •the lamp (or mirror) under

the stage that sends light through the object being viewed.

12. base •the bottom part that

supports the rest of the microscope

GOLDEN RULE

Before doing ANYTHING with your microscope, be sure that:

1.) STAGE IS ALL THE WAY DOWN

2.) ON Low power

Making a Wet Mount Slide

1. Use dropper to place a drop of water on the center of a clean slide.

2. Use tweezers to lay specimen on the drop of water.

3. Gently touch the cover slip to the edge of the drop of water to cover the specimen & the water.

Appearance of the Specimen

• Objects appear upside-down & backward

• Movement appears to be in opposite direction than actual movement 1 2

move slide slide appears to move

2 1

Field of View

• Field of view is the area (circle) that you see when looking through the eyepiece

Calculating Magnification1. Find the power of the lens. It is found

on the side of the lens. Magnification power of a lens is always identified by the label of x (10x, 1000x)

2. Multiply the power of the eyepiece by the power of the objective lens.

3. Examples: eyepiece obj. lens 10x times 100x 10x times 50x 10x times 40x

Recording Observations• Draw specimen large enough to fill

“field of view” circle• Draw as many details as possible• Drawing should be neat• Label specimen• Label power of magnification• Name & date on paper