Group Members:Ben Kensing Kevin Yee Nicole Tran Clark Plost Exercise____3__Date: ____2/8/14____ LI ______________________ Unique __________ Day: ___Wed_______ Room: _______ Lab Start Time __6_____ Exercise 3 Lab Report Adhere to UT’s Honor Code and course policies. Answer group questions individually first before compiling them into one consensus group response. Individual questions are to be answered independently. Balance between brevity and completeness. Show your work for all calculations and be sure to include proper units where necessary. Any secondary resources need to be cited. One printed report is to be submitted at the START of your next laboratory period as well as a digital pdf version uploaded to Canvas. (1)GROUP: Answer the following questions regarding the various microscopy types used. (a)Briefly describe when and why immersion oil is used. List the steps to properly use immersion oil on a slide with an oil-rated objective as well as cleanup afterward to examine a slide again at lower magnification. 1pt. Oil immersion is used when viewing small structures that are about 1 to 2 micrometers in dimension, such as individual bacteria. It is usually used with fixed specimen that are no thicker than a few micrometers. It is possible to use oil immersion to view a living wet mount specimen, but the wet mount must be very secure because the viscosity of the oil may cause the coverslip to shift during slide movement. (citation 1) Oil immersion is used to increase microscope resolution so that a specimen may be seen at 1000X total magnification. It does so by eliminating two air/glass boundaries where refractive index changes. When light passes from a material of one refractive index to another of different refractive index, it bends. In this case, the light passes through glass to air as it exits the coverslip and then through air to glass as it enters the microscope lens. Because different wavelengths of light bend at different angles, the magnified object becomes less distinct. By using an immersion oil with a refractive index identical to glass and putting the oil between the lens and cover slip, the light does not pass through air and thus does not bend from refractive index change. (citation 2) Oil immersion can only be used with the 100X oil immersion objective. A list of steps to properly use immersion oil can be seen below. 1. Bring the specimen into focus using the 40X objective 2. Rotate the nosepiece halfway between the 40X and 100X objective without turning off the illumination lamp or making any other adjustments 3. Place a drop of immersion oil on the coverslip over the beam of light 4. Slowly rotate the 100X objective into alignment 5. Bring the specimen into focus and observe 6. Turn off the illumination lamp 7. Rotate the nosepiece just enough so that the 100X objective is no longer in alignment, without aligning another objective 8. Remove the slide from the microscope stage 9. Use lens paper to wipe oil from the 100X objective lens and any other lens that may have contacted immersion oil 10. Use lens paper to wipe all oil from the surface of the slide. Use additional lens paper and lens-cleaning fluid to remove final traces of oil
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