 Identify the parts of a compound light microscope and explain their functions  Define magnification  Calculate the total magnification of the lenses that you are using to view an object  Describe the microscopes resolution, depth of field, and field of view  Describe how to prepare a slide  How to use a microscope properly  Describe how to correctly put a microscope away after use

 Tool used by biologists to see objects that are very small  Light passes through the specimen & through two sets of lenses (compound)  Specimen must be small enough & thin enough for light to pass through it, if not only a black silhouette can be seen

 Eyepiece (Ocular) ◦ used to view specimen (what you look into) ◦ holds a lens

 Body Tube ◦ permits light to pass through ◦ separates the eyepiece from the nosepiece

 Revolving Nosepiece ◦ holds objectives ◦ used to turn objectives into position

 High-power objective ◦ holds a lens ◦ used to make specimen larger for more detail ◦ magnifies 40x

 Low-power objective ◦ holds a lens ◦ used when first focusing in on a specimen ◦ magnifies 4x

 Stage ◦ used to hold specimen

 Stage clips ◦ used to hold slide in place

 Diaphragm ◦ regulates the amount of light that passes through the stage

 Mirror/Light source ◦ used to reflect/emit light

 Coarse adjustment ◦ used to raise and lower body quickly for focus  use first on low & medium power for approximate focus (but never use with high power objective)

 Fine adjustment ◦ used to make image clearer  use for final focusing on low & medium power (ALL focusing on high power!)

 Arm ◦ used to carry microscope

 Base ◦ used to support microscope ◦ also used to carry the microscope

 Purpose of microscope is to magnify an image BUT all microscopes are not created equal  Two scopes can have identical magnifications, but have differences in the qualities of resolution  Which microscope is more expensive?

 Magnification-the enlargement of an image created by the lenses  Our compound light microscopes have lenses in two locations ◦ 1. ocular/eyepiece ◦ 2. objectives  low power 4x  medium power 10x  high power 40x

 Objective lens magnification X Eyepiece magnification = Total Magnification ◦ i.e. 40X x 10X = 400X

 Resolution- (sharpness of an image) the capacity to show fine detail in clear focus  Using a cheaper scope with inferior resolution, it may be difficult to distinguish two things that are very close together; they may blur together to appear as one

 The term depth of field refers to the thickness (depth) of the layer that is currently in focus ◦ When one layer moves out of focus, another layer above or below the first layer, moves into focus

 The illuminated area that you are viewing is called the field of view ◦ Higher power objective lenses have a smaller field of view

 Obtain a clean slide & coverslip  Place specimen in middle of slide  Place a drop of water on specimen  Hold coverslip by thin edges between index finger and thumb  45 degree angle into drop of water  After water spreads along one edge of coverslip slowly lower until it lies flat on top of the slide  IF bubbles try again  Remove excess water with paper towel  Add drop to edge if it dries out

 Start on low power, medium light setting  Use coarse adjustment to first attempt to find the specimen  Once you have located the specimen using the coarse adjustment, finish focusing with the fine adjustment  Adjust light if necessary  To switch to medium, simply rotate nosepiece, refocus with fine adjustment, adjust diaphragm and position of slide as needed  To switch to high, repeat the steps above BUT BE CAREFUL THAT THE OBJECTIVE DOES NOT HIT THE SLIDE!!

 Rotate the nosepiece to the low power objective  Lower the body tube of the microscope down as close to the stage as possible by using the coarse adjustment  Wrap the cord neatly around the base  Place the plastic cover back on the microscope & return it to its proper slot within the cabinet  **Make sure that lab stations are neat & clean so your group does not lose any lab points!!**

 Pick a small area to “blow up” in your sketch  Fill the entire circle (PENCIL ONLY)  Label your sketches  Calculate total magnification for each sketch  Give a brief description of each specimen’s appearance  ALL sketches should be done on either medium or high power unless specified to sketch at low power

 **You must have your slide checked by me & your lab sheet marked before returning your clean slide to your lab station!** (If you do not do this your group will lose lab points)  **Make sure that lab stations are neat & clean so your group does not lose any lab points!!** (If lab stations are left messy all groups assigned to that station will lose lab points)

 Prepared Slide (from front of room)  Feather (small piece obtain from Mrs. Pettigrew)  Butterfly wing (small piece of wing) NO WET MOUNT  Human hair or cat hair (small sample)  Complete lab sketches & questions in handout (letter “e”, magazine picture, & yarn exercise)