MICROSCOPE

Question 1

A lab instrument used to view and examine objects that are too small to be seen by the
naked eye.

Answer 1

Microscope

Question 2

Light coming from a light source (mirror or bulb) will travel through the

Answer 2

specimen

Question 3

The light hitting the specimen will be focused (concentrated) by a lens or set of lenses called

Answer 3

objectives

Question 4

The focused light will now travel the tube/body through the ________ which further increases the magnification

Answer 4

eyepiece

Question 5

final image that an observer sees when viewing a microscope

Answer 5

virtual image

Question 6

virtual image can be affected by many factors, which can also be manipulated to get better quality images. Some of these factors are:

Answer 6

● The type of light (electromagnetic spectrum) used
● The properties or size of the object being observed
● Lens type and placement
● Contrast

Question 7

The degree on how a device can enlarge an object/specimen. In microscopes, this is provided by the lens.

Answer 7

Magnification

Question 8

Total magnification formula

Answer 8

(Objective magnification) x (Eyepiece magnification)

Question 9

Ability of a microscope to differentiate two adjacent objects as discrete entities

Answer 9

Resolution

Question 10

wavelength of light and numerical aperture (NA)

Answer 10

Resolution

Question 11

Resolving power formula

Answer 11

wavelength / 2 x Numerical aperture

Question 12

dictates the light gathering ability of the objective and the condenser

Answer 12

Numerical aperture

Question 13

Numerical aperture formula

Answer 13

= n sin (theta), where n = refractive index

Question 14

Measure of the bending of light as it passes from one medium to another

Answer 14

Refractive index

Question 15

Lights bends as it passes through the glass side which can cause

Answer 15

light dispersion

Question 16

can be used to lessen dispersion as it has same index as glass in higher magnification

Answer 16

oil

Question 17

Light source e.g., mirror or light bulb

Answer 17

Illumination

Question 18

collects the light from the light source and form into a cone of light that is focused on the
specimen

Answer 18

Condenser

Question 19

Used to adjust the size of the opening (aperture) in which the light passes through before reaching the condenser

Answer 19

Diaphragm

Question 20

During observation, most microscope objectives can be switched with minimal refocusing

Answer 20

Parfocality of Microscopes

Question 21

maintain focus even when focal length is changed

Answer 21

Parfocal lenses

Question 22

Interaction of the light and the specimen

Adding contrast between the specimen and the background can aid in the viewing the details of the specimen.

Answer 22

Contrast

Question 23

Electron Microscope

Answer 23

Transmission Electron Microscope (TEM)
Scanning Electron Microscope (SEM)

Question 24

specimens are visualized because of differences in contrast (density) between the specimen and surrounding.

Uses two set of lenses (objective and ocular)

Maximum magnification ~ 2,000X

Answer 24

Bright Field Microscope

Question 25

Uses a phase ring creates contrast without the use of dyes Live samples can be observed Dark cells on light background

Answer 25

Phase Contrast Microscope

Question 26

it can induce phase shifts due to brightness variation

Answer 26

phase ring

Question 27

Light from light source is blocked of thus light reaches the specimen from the side Best for observing motility

Answer 27

Dark Field Microscope

Question 28

Visualize specimens that fluoresce Fluorescence can be natural or induced (through staining e.g. using DAPI) Used in microbial ecology for enumeration of bacterial population

Answer 28

Fluorescence Microscope

Question 29

emit light when it absorbs other wavelengths of light

Answer 29

fluoresce

Question 30

Uses polarizer w/c creates two distinct beams of polarized light The polarized light can make some cell structure (e.g. vacuole, endospores, etc.) appear 3D

Answer 30

Differential Interference Contrast (DIC) Microscopy

Question 31

Computerized microscope + laser source The computer focuses the laser on single layers of the specimen Resolution is 0.1 μm

Answer 31

Confocal Scanning Laser Microscope (CLSM)

Question 32

Electromagnets serves as lenses High magnification and high resolution (0.2 nm) Requires a vacuum and specimens should be sliced thinly (20-60 nm)

Answer 32

Transmission Electron Microscope (TEM)

Question 33

stain used for Transmission Electron Microscope (TEM)

Answer 33

uranyl acetate and lead citrate

Question 34

Beams of electron hits heavy metal coated specimen heavy metal coat is used The electrons that will scatter will hit the detectors rendering an image Magnification 15x to 100,000 x

Answer 34

Scanning Electron Microscope (SEM)