microscope_lab

Question 1

What are the low power objective lens called and their x

Answer 1

Scanning objective lens 4x, Low Power objective lens 10x

Question 2

what are the correct order of steps to few a specimen at 40x

Answer 2

1. click power switch to turn on light
2. adjust light to appropriate brightness (contrast)
3. focus at 4x using coarse focus knob
4. Adjust ocular lenses to view one image
5. focus using fine focus knob
6. Adjust the stage to move the star to the center of microscope view
7. Put 10x objective in place
8. Focus using fine focus knob
9. Put 40x objective in place
10. Adjust using fine focus knob

Question 3

when was the microscope invented

Answer 3

shortly before 1600 by zacharias janssen

Question 4

The microscope was not used to examine microorganisms until___ when ______ examined scrapings of his teeth

Answer 4

1680, Antoni van Leeuwenhoek

Question 5

Wha were early microscopes consisting of biconvex lenses, called

Answer 5

simple microscopes

Question 6

whats a compound microscope

Answer 6

two lenses between the eye and the object, magnifies the object and illumination system (sun + mirror, or lamp) ensures enough light is available for viewing

Question 7

_____ shows dark object in a bright field

Answer 7

bright field microscope

Question 8

what does a stage do

Answer 8

holds the slide

Question 9

microscope arm

Answer 9

for carrying the microscope

Question 10

body tube

Answer 10

for transmitting the magnified image

Question 11

stage clips

Answer 11

to hold the slide

Question 12

above the light source is a ____

Answer 12

condensor

Question 13

what’s a condenser

Answer 13

consists of several lenses that concentrate light on the slide by focusing it into a cone

Question 14

iris diaphragm

Answer 14

the condenser has an iris diaphragm which controls the angle and size of the cone of light. AMOUNT of light

Question 15

revolving nose piece

Answer 15

holds 3-4 objective lens

Question 16

whats the magnification of the occular or eye piece

Answer 16

10-12.5x

Question 17

if a microscope has only one ocular lens

Answer 17

monocular microscope

Question 18

if a microscope has two ocular lenses

Answer 18

binocular microscope

Question 19

coarse adjustment knob

Answer 19

is used for focusing with low power objectives (4x and 10x), moves stage longer distances

Question 20

fine adjustment

Answer 20

is used for focuing with the high-power and immersion objective lenses

Question 21

field of vision

Answer 21

area seen through a microscope

Question 22

what are teh four objective lenses and their power

Answer 22

scanning lens (4x), low power lens (10x)
high power lens or high dry (40-45x), oil immersion lens (97 - 100x)

Question 23

how to find total magnification of object

Answer 23

multiple ocular lens magnification by objective lens

Question 24

the most important lens in microbiology is the

Answer 24

oil immersion lens

Question 25

optical system could be built to magniy much more than 1000x magnification but the _____ would be poor

Answer 25

resolution

Question 26

compound microscopes require a ___

Answer 26

light source

Question 27

light may be reflected to the ______ by a ______ under the stage.

Answer 27

condensor, mirror

Question 28

if your microscope has a mirror the ____ or a ____ can be used as a light source

Answer 28

sun or a lamp

Question 29

most compound microscopes have a built in_____ at the base for a light source.

Answer 29

illuminator (not usually used with mirror)

Question 30

the ______ of the light of an illuminator can be adjusted with a wheel that regulates the amount of current to the bulb

Answer 30

intensity

Question 31

intensit yof the light can be adjusted with a wheel that regulates the amount of _____ to the bulb

Answer 31

current

Question 32

higher magnification requires (more/less) which can be obtained by adjusting the _____

Answer 32

more, iris diaphragm

Question 33

another word for resolution

Answer 33

resolving power

Question 34

what is resolution or resolving power

Answer 34

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

Question 35

resolving power is expressed in units of

Answer 35

length

Question 36

the _____ the distance the better the resolving power

Answer 36

smaller

Question 37

what is the equation of resolving power?

Answer 37

RP = wavelength of light used / 2x numerical aperture

Question 38

smaller wavelengths of light ____ resolving power

Answer 38

improve resolving power

Question 39

This is an example of : as seen in electron microscopes, electrons have an extremely short weave length adn result in excellent resolving power

Answer 39

smaller wavelengths of light improve resolving power

Question 40

high numerical aperture _____ resolving power

Answer 40

improve

Question 41

electron microscope has a resolving power of

Answer 41

less than .2nm

Question 42

light microscope has a resolving power of about

Answer 42

200 nm

Question 43

where to find numerical aperture

Answer 43

engraved on the side of each objective lens

Question 44

what does numerical aperture depend on

Answer 44

depends on the maximum angle of the light entering the objective lens and on the refractive index (the amount the light bends) of the material (usually air) between the objective lens and the slide,

Question 45

whats refractive index

Answer 45

amount the light bends

Question 46

numerical aperture is abreviated ___

Answer 46

N.A.

Question 47

equation of N.A.

Answer 47

N.A. = N sin θ, where N = refractive index of medium θ = angle between the most divergent light ray gathered by the lens and the center of the lens

Question 48

why is light refracted when it emerges from the slide

Answer 48

because of the change in medium as the light passes from glass to air

Question 49

when immersion oil is placed between teh slide adn the oil immersion lens, the light ray continues without refraction because :

Answer 49

immersion oil has the same refractive index ( N = 1.52) as glass. when you look through immersion oil you can not see the glass rod inside

Question 50

the identical N values of the glass and immersion oil ____ light loss

Answer 50

minimizes

Question 51

as light rays pass through a lens they are bent to converge at the _____ where an image is formed.

Answer 51

focal point

Question 52

what is spherical aberration

Answer 52

when you bring the center of a microscope field into focus teh periphery may be fuzzy because of the curvature of the lens, resulting in multiple focus points.

Question 53

how to limit spherical aberration

Answer 53

minimized by using the iris diaphragm, which eliminates light rays to the periphery of the lens or using multiple lenses that result in a flat optical system

Question 54

whats chromatic aberration ?

Answer 54

caused by the prism like effect of the lens as various wavelengths of white light pass though to a different focal point for each wavelenngth.

Question 55

how to minimize chromatic aberrations

Answer 55

using filters (usually blue) by a lens systems corrected for red and blue light (achromatic lens) lens corrected for red, blue and other wavelengths (apochromatic lenses) use a light source of one wavelength(monochromatic light) most expensive.

Question 56

always focus by moving the lens ___ from the slide

Answer 56

away

Question 57

carry the microscope with ___ hands, one hand _____ the base and one hand on the ____

Answer 57

both hands, one hand beneath the base and one hand on the arm

Question 58

when using the low powered lens keep the ______ barley open

Answer 58

iris diaphragm - to achieve good focus

Question 59

t/f use only lens paper to clean lenses and wet if needed with opital lens cleaner

Answer 59

true

Question 60

t/fmake sure condensor is right below slide, may need to move up

Answer 60

true

Question 61

micrometer = how many meters

Answer 61

1 um = 1/1 millionth of a meter

Question 62

whats parfocal

Answer 62

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

Question 63

whats working distance

Answer 63

distance between the objective lens and the specimen

Question 64

t/f working distance increases as magnification increases

Answer 64

false decreases.