An important tool for studying life is the microscope. • The microscope magnifies objects so Microscopes you can see their veellfetery small features. Describe how simple lenses are used in • When you put brine a microscope. shrimp under a microscope, for instance, you can see many distinct features.

Location & Functions of Each Part Parts of a Microscope Eyepiece or Ocular Lens • Eyepiece Lens: The lens at the top which magnifies. They are usually 10x power.

Objective • Tube: Connects the eyepiece to the Arm Lenses objective lenses. • Arm: Supports the tube and connects it to Stage Stage clips the base Coarse knob Light Fine knob Base

The stage and light help you see the • Base: The bottom of the microscope, used for support specimen. • Stage: The flat platform where slides are • The stage is where you place held in place by the stage clips the object to be viewed. • Nosepiece: This is the part that holds – The stage can be moved up two or more objective lenses and can be or down to focus the image. rotated to easily change power. • The light source helps to • Objective Lenses: Lenses that can be illuminate the object to be rotated to easily change power. viewed. – The light can shine through a semitransparent object on a slide.

1 Microscopes enlarge by magnifying Eyepiece or through a convex lens. Ocular lens Most microscopes • Light rays that enter a convex lens parallel use at least two to its axis, refract and meet at the focal convex lenses. point.

Label them on your Objective paper. lens

Eyepiece Objective Lens

• The first lens you look • The second lens you Eyepiece through is called the look through, closest to the object to be Objective eyepiece and has a Lenses longer focal length. viewed, is called the objective. • The eyepiece acts like a magnifying glass, magnifying the (already larger) image from the objective.

The objective has a very short focal length and creates a larger, inverted • Usually you will find 3 objective lenses image of the object inside the on a microscope that are color coded. microscope. • Inverted means that the image appears upside down or backward compared with the actual object.

2 The shortest lens is the lowest power, the Each lens on a microscope has a longest one is the lens with the greatest power. magnification value. • The eyepiece lenses on our school microscopes have a 10X magnification • Many of the objective lenses on our school microscopes consist of – 4X, – 10X, and – 40X powers.

The total magnification of the image is So most of our school microscopes the power of the objective lens have a total magnifications of : multiplied by the power of the eyepiece.

• For example , a 10 eyepiece lens with a 6 objective lens produces an overall magnification of 60 (10 x 6).

Calculate the total magnification for Trace the path of light through a microscope. each combination of lenses on a microscope: • Notice the prism both refracts and reflects light rays. • a. objective lens: 10 eyepiece: 10 • bbjilb. objective lens: 2 eyepi5iece: 5

3 1. Turn on the microscope. 2. Click the nosepiece to the scanning objective – the shortest objective lens. Focusing the Image 3. Place the slide on the stage and secure it in place with the stage clips. 4. Adjust the slide to make sure the light hits the specimen on the slide.

5. Look through the eyepiece and focus Caring for a microscope using the coarse focus knob until the image is sharp. • Always carry the 6. After you have focused the specimen microscope with two using low power, don’t touch the hands. coarse focusing knob again. 7. CCgyspyontinue to magnify the specimen by • Keep cords clear from clicking the nosepiece to the next objects. longest objective. Fine Focus • Do not force the knobs. 8. Now, use the fine focus to bring the slide into focus. • Always turn off the 9. When you are done, turn off the light. microscope.

Biologists often need to make a biological drawing of their specimens. Biological Drawings

• Biological drawings are an important part of the science of biology and all biologists must be able to produce goodliiifidid quality scientific drawings regardless of your artistic ability. • Biological drawings follow certain rules.

4 Rules for Biological Drawings • Always use distinct, single lines when • Look at the specimen carefully and examine drawing. the significant features. • To illustrate darker • DRAW ONLY WHAT YOU SEE!! Do not areas on a specimen, include what you think you should see. use dots . • Only draw with a pencil. • Do not shade in any • Make your drawings large and clear so that area of your drawing. features can be easily distinguished.

Example: Insect Leg

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