Microbiology Lab Midterm Exam
Questions and Answers 100% Pass
Compound microscope - ✔✔1. Ocular-eyepiece lens (usually 10x)
2. Objective-nosepiece lenses (commonly 4x, 10x, 45x, and 100x)
At what magnification do you use the oil immersion technique? - ✔✔100x.
Total Magnification = - ✔✔Magnification (Objective) x Magnification
(Ocular)
Important Parts of the Microscope - ✔✔Framework, Stage, and Lens
System
Framework - ✔✔Arm and base are the structural parts of the microscope
which support the basic frame.
Stage - ✔✔Holds the slide. The mechanical stage clamps the slide and
moves the slide around the stage.
1
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,Lens System - ✔✔Oculars, Objective, and Condenser
Oculars - ✔✔Eyepiece lenses (usually 10x magnification)
Objectives - ✔✔Lenses attached to rotatable nosepiece, common
magnification of 4x, 10x, 45x and 100x.
Parfocalized microscope focusing adjustments are not to be made when... -
✔✔changing the objective lenses.
The oil has approximately the same refractive index as glass to prevent... -
✔✔light loss due to diffraction (bending of light rays) which would occur if
light traveled from one refractive index to another (eg. glass to air)
As magnification of the objective lens increases... - ✔✔the working distance
decreases.
Working distance - ✔✔distance between the object on slide and the
objective lens, when in focus.
Condenser - ✔✔directs light towards the objective lens in bright field
microscopy.
2
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, In dark field microscopy, the condenser... - ✔✔directs light at oblique
angles away from the objective lens in a manner that allows only objects in
the field of view to redirect or scatter light into the objective lens. This
causes objects to appear white on a dark field.
Iris Diaphragm - ✔✔lever located in the condenser that adjusts the
diameter of the cone of light so that it just fills the objective lens.
As you close down the Iris Diaphragm... - ✔✔1. The light intensity
decreases
2. Contrast improves
3. Depth of field increases
4. Limit Resolution (with oil immersion lens)
Resolution - ✔✔Resolving Power. Expressed as d.
d = the smallest distance between two objects which can be seen as
separate
d = the diameter of the smallest resolvable object
3
100% Pass Guarantee Katelyn Whitman, All Rights
Questions and Answers 100% Pass
Compound microscope - ✔✔1. Ocular-eyepiece lens (usually 10x)
2. Objective-nosepiece lenses (commonly 4x, 10x, 45x, and 100x)
At what magnification do you use the oil immersion technique? - ✔✔100x.
Total Magnification = - ✔✔Magnification (Objective) x Magnification
(Ocular)
Important Parts of the Microscope - ✔✔Framework, Stage, and Lens
System
Framework - ✔✔Arm and base are the structural parts of the microscope
which support the basic frame.
Stage - ✔✔Holds the slide. The mechanical stage clamps the slide and
moves the slide around the stage.
1
100% Pass Guarantee Katelyn Whitman, All Rights
,Lens System - ✔✔Oculars, Objective, and Condenser
Oculars - ✔✔Eyepiece lenses (usually 10x magnification)
Objectives - ✔✔Lenses attached to rotatable nosepiece, common
magnification of 4x, 10x, 45x and 100x.
Parfocalized microscope focusing adjustments are not to be made when... -
✔✔changing the objective lenses.
The oil has approximately the same refractive index as glass to prevent... -
✔✔light loss due to diffraction (bending of light rays) which would occur if
light traveled from one refractive index to another (eg. glass to air)
As magnification of the objective lens increases... - ✔✔the working distance
decreases.
Working distance - ✔✔distance between the object on slide and the
objective lens, when in focus.
Condenser - ✔✔directs light towards the objective lens in bright field
microscopy.
2
100% Pass Guarantee Katelyn Whitman, All Rights
, In dark field microscopy, the condenser... - ✔✔directs light at oblique
angles away from the objective lens in a manner that allows only objects in
the field of view to redirect or scatter light into the objective lens. This
causes objects to appear white on a dark field.
Iris Diaphragm - ✔✔lever located in the condenser that adjusts the
diameter of the cone of light so that it just fills the objective lens.
As you close down the Iris Diaphragm... - ✔✔1. The light intensity
decreases
2. Contrast improves
3. Depth of field increases
4. Limit Resolution (with oil immersion lens)
Resolution - ✔✔Resolving Power. Expressed as d.
d = the smallest distance between two objects which can be seen as
separate
d = the diameter of the smallest resolvable object
3
100% Pass Guarantee Katelyn Whitman, All Rights
