3-1 Flashcards
what are the components of the microscope?
- on and off switch
- substage condenser
- iris diaphragm
- stage
- mechanical stage
- objective lens
- revolving nose piece
- ocular lens
- turret and set screws
- coarse and fine coarse knobs
- stage clip
What does the substage condenser do?
condenses the beam of light onto the specimen
what does the iris diaphragm do?
controls light intensity of beam on the specimen
what does the stage do?
flat surface in which microscope slide rests
what is the mechanical stage?
allows movement of slide in all directions
also allows minute movement of slide
what is the objective lens?
magnifies the specimen and produces the real image
How many objective lens are there?
four
4X (scanning) red
10X (low dry) yellow
40X (high dry) blue
100x (oil immersion) white
ron yelled beware whitney
what is the revolving nose piece?
enables moving different objective lenses into position
what is the ocular lens?
two ocular lens (binocular)
10X in power
allows adjustment for eye separation and focusing differences for each eye produces more magnification and a virtual image
what are the turret and set screw?
allow loosening and rotation of oculars and locking of turret in position.
what are the coarse and fine focus knobs?
focus adjustment
large knob: coarse adjustment (moves stage up and down)
small knob: fine focus
what is the stage clip?
holds microscope slide to mechanical stage so that slide can be precisely positioned for viewing
formula for total magnification?
ocular power x objective power
what is resolution or resolving power?
the ability of the objective lenses to distinguish two points as clear and separate entities at a specific distance apart
clarity of an image
what is the formula for resolution/ resolving power?
RP=0.5xLambda/N.A
0.5: constant
Lambda: wavelength of light used t illuminate specimen
N.A: numerical aperature sine theta x i
(sine theta is the angle between specimen and center and outer edge of objective lens)
(i is index of refraction. How the speed of light is changed as it moves through one material into the other. As a result light is bent or refracted)
how does wavelength of light affect resolution of microscope?
shorter the wavelength, the better the resolution
when is immersion oil used?
100X objective
why is immersion oil used?
to change the index of refraction to improve the resolution of the microscope
reduces angle
how does one carry/handle a microscope?
carry with both hands
one hand at the base
other hand at the arm
how does one use the microscope?
- carry with both hands
- turn light on and adjust intensity to 3-4
- open iris diaphragm
- move 4x object into position
- open stage clip. place slide in position
- use coarse focus knob to bring stage to highest position
- use coarse focus to bring specimen into focus
- use focus knob to bring into sharp focus
- adjust width of ocular lens
- focus right ocular while left eye is closed
- with both eyes open adjust left ocular until left eye focus is sharp with right eye
- observe specimen
- lower stage, remove slide
- clean/ remove oil with lens paper using ethanol
- dry lens
- turn light intensity to its lowest, then turn off
- wrap electrical cord
- return to cabinet
When using the microscope, if field of view is dark, what is wrong?
check to see if light is on
check that iris diaphragm is wide open
make sure objective is clicked into position
when using microscope and the specimen is in focus on lower power objectives but not on higher power objectives, what is wrong?
smear is upside down
if so, wipe off immersion oil, turn smear right side up, add immersion oil, focus
when specimen is right side up, you can see smear, but cannot get it in focus, what do you do?
focus smear with 10x objective SLOWLY
then add immersion oil and turn to 100x objective, and focus with fine focus slowly in one direction and then back in the other direction
able to get smear or specimen in focus with 10x objective but not with 100x objective?
air bubble blocking 100x objective
turn 100x objective out and wipe off the oil
or
insufficient oil has been added to smear
or
100x objective not in oil
sufficient light available for focusing on specimen with 10x objective, however insufficient light to see specimen with 100x objective?
increase light intensity
check that iris diaphragm is wide open
cannot find specimen with any objective?
did not heat fix
specimen washed off microscope slide
what are two ways that you can improve resolving power on microscope?
- shorten wavelength of light
2. use immersion oil
what does parfocal mean?
lens stay in focus when you change objective
