microscopy (lab)

Question 1

Magnification is obtained by a system of optical lens

Answer 1

brightfield microscope

Question 2

Equipped with two lenses and a visible light source that passes through the specimen and lenses to the observer’s eye.

Answer 2

compound brightfield

Question 3

Objectives

Answer 3

Low-power objectives- 100x
High-power objectives- 400X
Oil-immersion objectives -1,000X

Question 4

Ability of the lens to distinguish two adjacent points or objects at a particular distance apart.

Answer 4

resolving power

Question 5

The light is directed toward the specimen from the side so that the only light to reach the objective is reflected from the bacteria or object to be studied.

Answer 5

dark field microscope

Question 6

It is used to observe living microorganism without staining because the light refracted by the living cells is different from the surrounding medium to see the object more easily.

Answer 6

phase-contrast microscope

Question 7

This microscope uses ultraviolet ( UV) light source that illuminates the object without passing into the objective of the microscope.

Answer 7

fluorescence microscope

Question 8

It uses electron beam instead of visible light and magnets instead of lenses to focus the beam.

Answer 8

electron microscope

Question 9

The object can be viewed on the screen and allows examination of cellular ultrastructure, as well as viruses.

Answer 9

transmission electron microscope

Question 10

It shows three dimensional view of specimen. it is also useful in examining surface structure of cells and viruses.

Answer 10

scanning electron

Question 11

Resolving power- 0.0200 um.
Maximum magnification- 10,000X

Answer 11

scanning electron

Question 12

Resolution is limited compared with transmission electron microscope.

Answer 12

scanning electron

Question 13

Image is two dimensional

Answer 13

transmission electron

Question 14

Resolving power- 0.0005 um.
Maximum magnification - 200,000X

Answer 14

transmission electron

Question 15

The electron passes through the dry specimen, which is mounted in wax or plastic, and the image is seen on the fluorescent screen.

Answer 15

electron microscope

Question 16

The ultraviolet light strikes certain dye (fluorescein isothiocyanate, rhodamine B ) and pigments they emit fluorescent against a dark background.

Answer 16

fluorescence microscope

Question 17

Eyepiece contains the ocular lens, the next lens is in the objectives near the object to be viewed.

Answer 17

compound brightfield microscope

Question 18

Form a dark image against a brighter background (Resolving power - 0.2000 um.)

Answer 18

compound brightfield microscope

Question 19

It depends on the wavelength of the light source and the numerical aperture.

Answer 19

resolving power

Question 20

The numerical aperture is proportional to the resolving power.

Answer 20

resolving power

Question 21

The microbes appear as bright object on a dark background.

Answer 21

dark field microscope