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Microscope_lab > microscope_lab > Flashcards

microscope_lab Flashcards

1
Q

What are the low power objective lens called and their x

A

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

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2
Q

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

A
  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
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3
Q

when was the microscope invented

A

shortly before 1600 by zacharias janssen

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4
Q

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

A

1680, Antoni van Leeuwenhoek

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5
Q

Wha were early microscopes consisting of biconvex lenses, called

A

simple microscopes

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6
Q

whats a compound microscope

A

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

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7
Q

_____ shows dark object in a bright field

A

bright field microscope

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8
Q

what does a stage do

A

holds the slide

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9
Q

microscope arm

A

for carrying the microscope

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10
Q

body tube

A

for transmitting the magnified image

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11
Q

stage clips

A

to hold the slide

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12
Q

above the light source is a ____

A

condensor

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13
Q

what’s a condenser

A

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

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14
Q

iris diaphragm

A

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

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15
Q

revolving nose piece

A

holds 3-4 objective lens

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16
Q

whats the magnification of the occular or eye piece

A

10-12.5x

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17
Q

if a microscope has only one ocular lens

A

monocular microscope

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18
Q

if a microscope has two ocular lenses

A

binocular microscope

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19
Q

coarse adjustment knob

A

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

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20
Q

fine adjustment

A

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

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21
Q

field of vision

A

area seen through a microscope

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22
Q

what are teh four objective lenses and their power

A

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

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23
Q

how to find total magnification of object

A

multiple ocular lens magnification by objective lens

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24
Q

the most important lens in microbiology is the

A

oil immersion lens

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25
Q

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

A

resolution

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26
Q

compound microscopes require a ___

A

light source

27
Q

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

A

condensor, mirror

28
Q

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

A

sun or a lamp

29
Q

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

A

illuminator (not usually used with mirror)

30
Q

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

A

intensity

31
Q

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

A

current

32
Q

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

A

more, iris diaphragm

33
Q

another word for resolution

A

resolving power

34
Q

what is resolution or resolving power

A

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

35
Q

resolving power is expressed in units of

A

length

36
Q

the _____ the distance the better the resolving power

A

smaller

37
Q

what is the equation of resolving power?

A

RP = wavelength of light used / 2x numerical aperture

38
Q

smaller wavelengths of light ____ resolving power

A

improve resolving power

39
Q

This is an example of :

as seen in electron microscopes, electrons have an extremely short weave length adn result in excellent resolving power

A

smaller wavelengths of light improve resolving power

40
Q

high numerical aperture _____ resolving power

A

improve

41
Q

electron microscope has a resolving power of

A

less than .2nm

42
Q

light microscope has a resolving power of about

A

200 nm

43
Q

where to find numerical aperture

A

engraved on the side of each objective lens

44
Q

what does numerical aperture depend on

A

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,

45
Q

whats refractive index

A

amount the light bends

46
Q

numerical aperture is abreviated ___

A

N.A.

47
Q

equation of N.A.

A

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

48
Q

why is light refracted when it emerges from the slide

A

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

49
Q

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

A

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

50
Q

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

A

minimizes

51
Q

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

A

focal point

52
Q

what is spherical aberration

A

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.

53
Q

how to limit spherical aberration

A

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

54
Q

whats chromatic aberration ?

A

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.

55
Q

how to minimize chromatic aberrations

A

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.

56
Q

always focus by moving the lens ___ from the slide

A

away

57
Q

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

A

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

58
Q

when using the low powered lens keep the ______ barley open

A

iris diaphragm - to achieve good focus

59
Q

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

A

true

60
Q

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

A

true

61
Q

micrometer = how many meters

A

1 um = 1/1 millionth of a meter

62
Q

whats parfocal

A

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

63
Q

whats working distance

A

distance between the objective lens and the specimen

64
Q

t/f working distance increases as magnification increases

A

false decreases.

Microscope_lab (13 decks)

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