2. MICROSCOPES

3. Some Important Vocabulary MAGNIFICATION- increase of an object’s apparent size RESOLUTION- the power to show details clearly * Microscopes vary in powers of magnification and resolution

4. LIGHT MICROSCOPES These are the types of microscopes that we will use in class, along with dissecting scopes - a specimen must be mounted on a slide in order to be viewed with a compound microscope - specimens must be sliced thin enough to be transparent, or they must be very small - light microscopes have a total magnification of 400X

5. - images produced are always backwards and upside down from the way that the slide looks * if you move the slide away from you, it appears to be moving toward you * if you move the slide to the left, it appears to be moving to the right - you should always view a specimen by starting on the lowest magnification

6. As you go from low to high power: 1. Resolution decreases 2. Field of view (how much of the specimen you can see) decreases- although you can see the specimen closer, you cannot see as much of it

7. How to prepare a wet mount slide Many slides used on the light microscope are wet mount slides To Make a Wet Mount Slide- 1. Obtain a clean slide and cover slip 2. Place your thin specimen on the middle of the slide 3. Place a drop of water or stain on the specimen 4. Cover with the cover slip

8. STEREOSCOPIC/DISSECTING MICROSCOPE - enables you to observe objects that are too thick or too large to see with other microscopes - provides an opportunity for three dimensional viewing and viewing of live specimens - direction of movement of the object is the same as the way you move it; images are not backwards

9. ELECTRON MICROSCOPES Resolution of light microscopes is limited by the physical characteristics of light - at powers beyond about 2,000X the image of the specimen becomes blurry In electron microscopes, a beam of electrons instead of a beam of light produces an enlarged image of the specimen

10. - some electron microscopes can even show individual atoms in a specimen There are 2 types of electron microscopes: 1. Transmission electron microscopes (TEM) 2. Scanning electron microscopes (SEM)

11. TEM - transmits a beam of electrons through a very thinly sliced specimen - magnetic lenses enlarge the image and focus it on a screen - these microscopes can magnify objects up to 200,000 times, but cannot be used to view living specimens

12.  Transmission Electron Microscope Transmission Electron Microscope Transmission Electron Microscope

13.  TEM Image TEM Image TEM Image - images

14. SEM - provides three-dimensional images - specimens are not sliced for viewing - the surface of the specimen is sprayed with a fine metal coating, and a beam of electrons is passed over the specimen’s surface - this causes the metal coating to emit a shower of electrons

15. - the electrons are focused onto a screen, producing an image of the surface of an object - can magnify up to 100,000 times, but also cannot be used to view living specimens

16.  Scanning Electron Microscope Scanning Electron Microscope Scanning Electron Microscope  SEM - Scanning Electron Microscopy Image Gallery SEM - Scanning Electron Microscopy Image Gallery SEM - Scanning Electron Microscopy Image Gallery  http://www.mos.org/sln/sem/sem.html http://www.mos.org/sln/sem/sem.html

17. DIGITAL MICROSCOPES Digital microscopes have many of the features of light microscopes and stereoscopic microscopes, along with some additions: -Digital microscopes enable us to take pictures of specimens -Digital microscopes enable us to view specimens on a TV screen or a projector -Digital microscopes enable us to easily share an interesting specimen with the rest of the class