1. Tools of Science The Microscope

2.  An instrument that can form an enlarged image of an object.  Visible light is passed through the specimen and through glass lenses. The lenses refract light to enlarge the image projected to the eye.

3. Schematic of Light Microscope

4. Properties of Microscopes  Magnification- how much larger compared to the real size The two lenses are the ocular and objective lens. To determine magnification, multiply the magnifying power of the ocular by the magnifying power of the objective lens.

5. Properties of Microscopes  Resolving Power a. a measure of clarity b. minimum distance between two points that can still be distinct as two points.

6. Limitation on Resolution Limit is.2 micrometers Limit is set by the wavelength of light (400- 700nm or.4 micrometers)

7. Rayleigh Criterion

8. The Electron Microscope 1931 Ernst Ruska invented the electron microscope Beam of electrons focused by magnets. Wavelength of a resonating electron is.004nm. The resolution is limited by the ability to focus electrons with a magnet to approximately.2nm. The resolving power of the microscope is inversely related to the wavelength of electromagnetic radiation used. The specimen will be dead!!!

9. TEM Transmission electron microscope used to view internal structure. 200,000x

10. SEM-Scanning Electron Microscope Surface sprayed with metallic mist. Scans surface of objects with electrons. Electrons bounce off of surface and are projected on a screen. Image appears 3D. 100,000x magnification of cell surface ultrastructure.

11. Schematic of SEM

12. Scanning Tunneling Microscope Specimen can be living!!!! 100 million x Electrons tunnel off of any surface and and electron gun measures the electron cloud thickness. Uses electrons that leak from the surface.