lab notes

Question 1

what are simple microscopes?

Answer 1

early biconvex lenses that were basically magnifying glasses

Question 2

what is a brightfield compound microscope?

Answer 2

shows dark objects in a bright field

Question 3

parts of a brightfield compound microscope

Answer 3

base, stage, arm, body tube, condenser, iris diaphragm, objective lenses, ocular/eyepiece lenses, coarse and fine adjustment, illuminator

Question 4

what is coarse adjustment used for?

Answer 4

4x (scanning) and 10x (low power)

Question 5

what is fine adjusment used for?

Answer 5

40x (high power/dry) and 100x (oil immersion)

Question 6

field of vision

Answer 6

the area seen through the microscope

Question 7

depth of vision

Answer 7

the thickness of the object in focus at one time

Question 8

how many lenses are there in a compound microscope and what are they?

Answer 8

3/4 lenses = 4x (scanning), 10x (low-power), 40x (high-power/dry), 100x (oil immersion)

Question 9

resolution/resolving power

Answer 9

the ability of a lens to reveal fine detail or two points distinctly separated

Question 10

ocular lens

Answer 10

aka eyepiece; remagnifies the image formed by the objective lens

Question 11

what does higher magnification require?

Answer 11

more light which can be adjusted by the iris diaphragm

Question 12

what does lower magnification require?

Answer 12

less light

Question 13

is the resolving power better or worse when the distance is smaller?

Answer 13

better

Question 14

refractive index

Answer 14

a measure of the light-bending ability of a medium

Question 15

what does immersion oil have the same refractive index as?

Answer 15

glass (N = 1.52)

Question 16

what does immersion oil do?

Answer 16

keeps light rays from refracting

Question 17

what is the focal point?

Answer 17

where the light rays converge after they pass through a lens

Question 18

where is the image formed in a microscope?

Answer 18

focal point

Question 19

why does the periphery become blurry when focusing a microscope?

Answer 19

spherical aberration caused by the curved lens (multiple focal points)

Question 20

how can you minimize spherical aberrations?

Answer 20

use the iris diaphragm to lessen light rays to the periphery

Question 21

what is chromatic aberration and what is it caused by?

Answer 21

when multiple colors are seen in the field caused by the prism-like effect of the lens

Question 22

how to minimize chromatic abberations?

Answer 22

filters such as blue and red

Question 23

what are achromatic lenses?

Answer 23

lens systems corrected for blue and red lights

Question 24

what are apochromatic lenses?

Answer 24

lens systems corrected for blue and red lights and other wavelengths

Question 25

what is monochromatic light?

Answer 25

using the light source of one wavelength

Question 26

how should you carry the microscope?

Answer 26

two hands; dominant hand on the arm and another beneath the base

Question 27

what lens should you always begin with?

Answer 27

low-power

Question 28

all of the lenses are __?

Answer 28

parfocal

Question 29

what does parfocal mean?

Answer 29

when a subject is in focus with one lens, it will be in partial focus with all of the lenses

Question 30

when changing the magnification, what else changes?

Answer 30

the working distance

Question 31

what is the working distance?

Answer 31

distance between objective lens and specimen

Question 32

what should you use to clean the lens?

Answer 32

lens paper or kim wipe

Question 33

what are the 3 basic shapes of bacteria?

Answer 33

bacillus (rods), coccus (spheres), spiral

Question 34

1 micrometer = __ m = __ mm

Answer 34

1 micrometer = 10^-6 m = 10^-3 mm

Question 35

1 nm = __ m = __ mm

Answer 35

1 nm = 10^-9 m = 10^-6 mm

Question 36

short focal length = __?

Answer 36

more magnification

Question 37

numerical aperture

Answer 37

depends on the maximum angle of the light entering the objective lens and on the refractive index

Question 38

what can brightfield microscopy be used for?

Answer 38

observing unstained microbes in wet mounts and hanging drop slides

Question 39

brownian movement

Answer 39

object shaking/bouncing because of liquid molecules striking against them

Question 40

in brownian movement, the particles and microbes all ___?

Answer 40

vibrate around the same rate and maintain their relative positions