Microscopes Biology

Light Microscope (LM) [aka Compound Microscope] Visible light is projected through the specimen. Glass lenses enlarge the image & project it into the human eye. Useful for studying living cells

Magnify me! Resolving power: the ability of an optical instrument to show 2 objects as separate Magnification: increase in an object’s apparent size compared to its actual size Eyepiece vs. Objective Lens Total magnification= magnification of the eyepiece x magnification of the objective lens

Electron Microscope (EM) Uses beams of electrons, instead of light to resolve objects Better resolving power than light microscope (improvement  “better to see you with my dear!” Cells must be killed & preserved before they can be examined 2 kinds: TEM & SEM

Transmission Electron Microscope (TEM) Useful for exploring the internal structure of a cell

Scanning Electron Microscope (SEM) Used to study the detailed architecture of the surface of a cell Magnifies up to 2 million times larger

Dissection Microscope Configured to allow low magnification of three-dimensional objects- objects larger or thicker than the compound microscope can accommodate

Eyepiece Body Tube Revolving Nosepiece Arm Objective Lens Stage Stage Clips Coarse Focus Fine Focus Base Diaphragm Light

Proper Care of Microscopes Hold base & arm using TWO hands, NEVER by the eyepiece Do NOT touch the lenses with your hands; only use LENS PAPER to clean Be careful with slides- they can be made of glass & could you cut you if broken! This goes for cover slips too!!

Proper Care of Microscopes Always lower the stage to the starting position, and position the nosepiece on the lowest power objective when putting away Turn OFF your microscope light & unplug; winding cord around base Clean stage if necessary Replace plastic cover

Put LOW power objective into place (shortest one). Place the slide on the stage & use stage clips to secure.* Look into the eyepiece. Use the coarse & fine adjustment knobs to focus. Move MEDIUM power objective into place & repeat. Do NOT lower the stage in order to move the next objective into place. The microscopes are designed to “stay focused” when moving to another objective.

Move HIGH power objective into place. Do NOT use the coarse adjustment knob. Use only the fine adjustment knob to bring the slide into focus.

Tips for Drawing Microscope Images Look at your image (if it is large enough) on the stage BEFORE you focus & draw Don’t draw everything on your slide. Just concentrate on 1 or 2 of the images. You can draw things larger than you see them. This will help you show all of the details you see. Use the space you are given to draw the entire field of view! Remember to record the level of magnification next to your drawing.

Making a wet mount Place specimen you want to observe in the center of the slide. Using a dropper, place a drop of water on the specimen. Hold a coverslip at the edge of the water drop at a 45 o angle. The water should spread along the edge of the slide. Slowly lower the coverslip over the specimen, avoiding air bubbles. Remove excess water.

Making a wet mount… Ouch!! Science hurts!