THE COMPOUND MICROSCOPE

Question 1

There are two general categories of microscopes:

Answer 1

light microscope and the electron type

Question 2

which uses light
waves and lenses that are associated with the _____ microscope,

Answer 2

light microscope

Question 3

which employs electron beams and magnetic fields to produce the image.

Answer 3

electron type

Question 4

Light microscopes can be classified as simple if they have short ______, are held close to the eye and magnify objects only up to ______X.

Answer 4

focal length,
300X

Question 5

On the other hand, the compound type
employs two separate lenses, an ___ and an ________, in order to achieve ____ times greater
magnification.

Answer 5

ocular, objective

2-5

Question 6

Other types of microscopes include (5)

Answer 6

bright field
dark-field
ultraviolet (UV)
fluorescent
phase-contrast

Question 7

type of microscope where the microscope field is brightly lighted and the object to be observed appears dark die to its ability to absorb or refract some of the incident light

Answer 7

bright field microscope

Question 8

type of microscope where the object appears luminous against a dark background since it reflects some of the incident light in all directions

Answer 8

dark-field microscope

Question 9

type of microscope which uses UV light, thereby allowing greater resolution and magnification. It is used principally to detect or even measure substances in
specimens of living tissues that are known to absorb UV light at particular wavelengths. UV is not visible to the eye, so the image formed is recorded with the use of cameras or a television screen.

Answer 9

Ultraviolet (UV) microscope

Question 10

type of microscope which makes use of the property of certain chemical substances that release light at a different wavelength when exposed to UV rays. Such substances convert UV light into visible waves of greater length. Bacteria and other microorganisms are stained with fluorescent stain that can be detected in a microscope illuminated with UV light.

Answer 10

Fluorescent microscope

Question 11

type of microscope which utilizes the refraction that occurs when light passes from one medium into another of different density. The special objectives and condenser intensify slight differences in contrast produced by this bending of
light. It is useful in studying the internal structures of microorganisms because
structures differing in refractive index from the surrounding protoplasm become
visible, and their sizes and locations can be determined.

Answer 11

Phase-contrast microscope

Question 12

keeps the microscope steady at any position of the stage

Answer 12

base

Question 13

fastened to the base through the inclination joint, permits the adjustment of the stage to
a desired angle.

Answer 13

arm

Question 14

reflects the light into the condenser.

Answer 14

concave mirror

Question 15

concentrates the light rays received from the mirror and sends them to the objective

Answer 15

condenser

Question 16

is a horizontal platform upon which the specimen to be examined is placed.

Answer 16

stage

Question 17

At the center of the stage is a

Answer 17

circular aperture.

Question 18

hold the slide in place on the stage.

Answer 18

stage clips

Question 19

is that part of the optical system of the microscope which produces the specimen’s
initial magnified image (real) within the body tube.

Answer 19

objective

Question 20

The student microscope has three objectives:

Answer 20

a dry low power, a dry high power, and an oil
immersion objective.

Question 21

The objectives are ________, that is, they are corrected for the spectral colors of red and blue.

Answer 21

achromatic

Question 22

Important features of the objectives: (4)

Answer 22

a. Focal length
b. Resolving power
c. Numerical aperture (N.A.)
d. Parfocal

Question 23

an optical constant of the lens system, is the distance from the center of the lens to the point where parallel rays entering the lens are brought to a focus.

Answer 23

Focal length (mm),

Question 24

of an objective is that property to recognize features of a specimen that are close to each other as separate or distinct.

The greater the _____, the greater the definition of an objective.

is dependent on the wavelength of light used and an optical property of the objective lens known as a numerical aperture.

Answer 24

Resolving power

Question 25

is a measure of the resolving power of an objective.

An objective with a 0.25 N.A. allows the viewer to distinguish as separate 25,000 lines per inch.

If the specimen is known to be of the order of 26,000 lines per inch, the observer can never see the line as separate no matter how much magnification is employed.

Answer 25

Numerical aperture (N.A.)

Question 26

means that the objectives are optically ad mechanically designed so that the distance between the specimen and the aerial image is always constant. Slight refocusing with the aide of the fine focus knob is sufficient to restore critical sharpness of the image after changing from one objective to another, thus, the coarse focus knob need not to be
operated.

Answer 26

Parfocal

Question 27

to which parfocal objectives are attached, allows convenient shifting of the objectives.

Answer 27

revolving nosepiece

Question 28

______ is a hollow cylindrical tube through which light passes from the objective to
the eyepiece. The upper portion of the body tube is called the ________.

Answer 28

body tube; draw tube

Question 29

is that part of the optical system through which the specimen is viewed. The intermediate image projected by the objective is enlarged by this.

Answer 29

eyepiece or ocular

Question 30

the term compound microscope is derived from the fact that the specimen is magnified twice, first by the _____ and second by the ______. The final image formed is a ____________.

Answer 30

objective, eyepiece

virtual image

Question 31

the product of the magnifying power of the objective and the eyepiece

Answer 31

magnification of the compound microscope

Question 32

is used to bring the objective into approximate focus.

Answer 32

coarse focus knob

Question 33

For maximum definition, the _________ is used.

Answer 33

fine focus knob

Question 34

comprise the optical system. (4)

Answer 34

The mirror, the condenser, the objective
and the eyepiece

Question 35

consist of systems of lenses (3)

Answer 35

The condenser, the objective and the eyepiece

Question 36

Microscopic objects can be measured by means of an _________ or __________. Both must be calibrated first with the ________.

Answer 36

ocular or a Filar micrometer;

stage micrometer

Question 37

The unit of linear measurement in microbiology is the ________, which is equivalent to 1/1000 mm or 1/25,400 inch.

Answer 37

micrometer (μm)

Question 38

is a glass disc with mounted scale. It may
or may not have numbers on it. It is inserted into the eyepiece and must be calibrated for
the particular objective, eyepiece and tube length before measurements are made. The
student microscope has a fixed tube length.

Answer 38

The ocular micrometer

Question 39

is a glass slide with graduations of known
intervals. Some micrometers have numbers to indicate the length of the divisions. One
small division is 0.01 mm or 10 μm, where one big division is 0.1 mm or 100 μm.

Answer 39

stage micrometer

Question 40

CF (value of one ocular micrometer division)

Answer 40

(SM division subtended by OM divisions x Value of one SM division (micrometer)) / OM Divisions subtended by SM divisions