Lab quiz: Microscopes Flashcards
When switching from lower to higher power lens, how do you avoid the specimen from disappearing from your field?
How to correct this problem?
Center the specimen in the field before increasing magnification
Return to scanning lens, find the specimen then center it in the field. After, increase the magnification.
What is the total magnification for the different lens?
Scanning lens: 10 x 4 = 40x
Low power: 10 x 10 = 100x
High power: 40 x10 = 400x
Oil immersion: 100 x 10 = 1000x
How is total magnification calculated when using different object lenses?
Multiply magnification of oculars by the magnification of the lens.
What happens to field, working distance, and depth of field, when you increase the magnification?
All decreases
Depth of field
Distance which all objects, close and far, are in crisp focus
Working distance
Vertical space between specimen and objective when in focus
Field
Distance across visible. circular area
Why do objects appear up-side down, or move in opposite direction, when looking through oculars?
Microscopes contain mirrors which reflects the sample backwards
Which is only objective lens that the course adjustment knob should be used with? Why?
Scanning lens
Allows us to find specimen easier in field
Mechanical stage
Moves slide around stage
Occular
What we look through
Magnify 10x
Mechanical stage knobs
Upper knob moves slide toward and away us
Lower knob moves slide right and left
What are the four objective lenses and their power of magnification?
Scanning lens: 4x
Low power: 10x
High power: 40x
Oil immersion: 100x
Iris diaphragm
Opens and closes aperture to control beam of light
Course and fine adjustment knobs
Raise and lower stage to focus
Stage
Where slide is placed
