MICROSCOPES Describe the properties of microscopes Microscope a

MICROSCOPES

Describe the properties of microscopes. • Microscope: a device used to produce magnified images of objects too small to see with naked eye • Magnification: increase in size • Resolution: increase in detail • Two types: • Light microscopes • Electron microscopes

Light Microscopes • Magnifies objects using light • Simple microscopes: have only one lens (magnifying glass) • Compound light microscope: has two lenses • Diagram in your book appendix D pages 1064 & 1065

Parts of a microscope • Ocular lens: lens near eye • Eyepiece: holds ocular lens • Objective lens: lens near specimen a. high power lens: longer, usually 40 X b. low power lens: shorter, usually 10 X • Nosepiece: holds objective lenses • Stage: platform supporting specimen • Diaphragm: regulates amount of light • Fine adjustment/coarse adjustment: used to focus on object • Arm: supports microscope • Illuminator: light source

Using the microscope: • Find total magnification: multiply the power of eyepiece (usually 10 X) and the power of objective lens • When focusing: always start with LOW POWER objective • Move nosepiece all the way down and focus slowly UPWARD using the coarse adjustment

Microscope development: • Hans and Zacharis Janssen: 1590 mounted two lenses in a tube • Anton van Leeuwenhoek: early 1660’s used simple microscope to view blood, rainwater, etc. He was the first to study nature with microscope and made detailed drawings

Electron Microscopes • made in the 1940’s, uses electron beams instead of light • Allows more detail, but specimens are usually killed in the staining process • Two types: • TEM: beam goes through specimen • SEM: scans surface only

Quiz 1 1. The ___ of a microscope in an increase in the detail shown in the specimen. a. fragmentation b. magnification c. resolution 2. What part of the microscope holds the ocular lens? a. eyepiece b. nosepiece c. stage 3. A lens which has 100 X written on it would be the ___ lens. a. eyepiece lens b. high power c. low power 4. The ___ allows light to pass through the specimen. a. diaphragm b. eyepiece c. ocular opening 5. To find the total magnification for a microscope, you would ___ the power on the ocular lens and the power of the objective lens. a. add together b. divide c. multiply