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15 Cards in this Set

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Be able to list and diagram the parts of a microscope (16).
-ocular lens -ocular eyepiece -diopter ring -revolving nosepiece -eyepiece sleeve -objectives -mechanical stage with travel knobs -coarse and fine adjustment knobs -condensor -rheostat -arm -base -stage
What are the 6 working regions of a microscope?
-ocular
-objectives (red, yellow/green, blue, white)
-specimen stage
-substage condenser and light source
-focus control
-base
How can you control intensity and quality of light reaching the objective?
-rheostat (on-off switch)
-iris diaphragm (open has lower contrast, better resolve)
-condenser
When is the greatest intesity of light on the specimen in terms of the condenser?
Where should it be positioned for stained and wet mounts?
-when it's at its highest position
*stained smears: 102mm below slide
*wet mounts: lowest level
Who made the first microscope?
-Anton Van Leeuwenhoek
What is the microscope we will mostly be using in this lab?
-the compound brightfield microscope
What are the three lens' used in todays compound microscope?
-condenser
-objective lens
-ocular lens
Why does the 100X need oil?
-It can't take in enough light to be useful
-oil has similar refractive index so light isn't scattered as much and results in greater resolution
What are the markings found on each objective?
-E=type of objective
-100=objective magnification
-1.25 oil=numerical aperture
-160/0.17= mechanical tube length/cover glass thickness correction
How do you find the resolution for a microscope?
wavelength light/(NA obj lens + NA con lens)
What is the calculation for finding NA?
NA= n sin(theta)
n= refractive index of medium between specimen and lens
sin(theta)= sin function of half the total angle of the cone of light trapped by the lens
What are the two fixed faxtors when calculating the resolution of a lens?
-wavelength of visible light
-angle of incident light rays trapped by objective can not be greater than 60 degrees (sin < 0.866)
What does parfocal mean?
-When switching from low to higher power, image should be nearly focused
*use only fine focus knobs!
What should you check before putting the scope back in its cabinet?
-4x objective over hole
-clean all lenses
-using kimwipe, clean any oil or debris off stage
-fold cord and put under stage on base
-center slide older
-cover microscope
Be able to describe how to observe a sample in the microscope.
pg's 9 and 10 in Appendix A