Lab- Microscopes

Question 1

What is magnification ?

Answer 1

Enlargement of object

Question 2

What is resolution?

Answer 2

Degree to which detail is maintained in magnified image

Question 3

What is resolving power?

Answer 3

Minimum spacing between 2 points where can be clearly seen as separate entities

Question 4

What is the light source of a Brightfield microscope?

Answer 4

Visible light

Question 5

What is the light source of a Darkfield microscope?

Answer 5

Visible light

Question 6

What is the light source of a Fluorescence microscope?

Answer 6

UV light

Question 7

What is the light source of a Transmission Electron Microscope ( TEM)?

Answer 7

Electrons

Question 8

What is the light source of Scanning Electron Microscope?

Answer 8

Electrons

Question 9

What is the magnification of a Brightfield Microscope?

Answer 9

1500x

Question 10

What is the magnification of a Darkfield Midroscope?

Answer 10

1500x

Question 11

What is the magnification of a Fluorescence microscope?

Answer 11

1500x

Question 12

What is the magnification of a Transmission Electron Microscope?

Answer 12

500,000 -1,000,000x

Question 13

What is the magnification of a Scanning Electron Microscope?

Answer 13

10,000- 1,000,000x

Question 14

What is the wavelength of visible light?

Answer 14

550nm

Question 15

What is the wavelength of UV light?

Answer 15

100- 400nm

Question 16

What is the wavelength of light produced by electrons?

Answer 16

0.005 nm

Question 17

What is the limit of resolution of visible light?

Answer 17

220nm

Question 18

What is the limit of resolution of UV light?

Answer 18

110nm

Question 19

What is the limit of resolution of electrons?

Answer 19

0.2 nm

Question 20

What is the relation between limit of resolution and magnification capability ?

Answer 20

As the limit of resolution becomes smaller, the magnif8dation capability increases

Question 21

What is the conventional technique of microscopy?

Answer 21

Brightfield Microscopy

Question 22

When Brightfield Microscopy suitable?

Answer 22

Suitable fir observing the natural colors of a specimen or the observation of stained samples

Question 23

How do colors contrast in Brightfield microscopy?

Answer 23

The specimen appears darker on a bright background

Question 24

Why are stains used in Brightfield Microscopy?

Answer 24

Stains used to aid in increasing the contrast of cells so they are more easily visible

Question 25

Describe how images appear in Darkfield Microscopy

Answer 25

Specimens appear bright on a dark background Specimens appear bright, because they reflect the light from the microscope into the objective

Question 26

When is Phase Contrast Microscopy used and why?

Answer 26

- Widely used for examining such specimens as biological tissues - Able to show components in a cell or bacteria that can be difficult to see using an ordinary light microscope

Question 27

How does Phase Contrast Microscope work?

Answer 27

A type of light microscopy that enhances contrast of transparent and colorless objects by influencing the optical path of light so that they show light/bright on a contrasting background

Question 28

Give the 3 differences of SEM and TEM based on cellular composition, electrons and observed samples

Answer 28

Composition- TEM observed intracellular composition while SEM observes the surface of the cell and its composition Electrons- TEM is based on transmitted electrons while SEM is based on scattered electrons Sample - TEM sample has to be cut thinner to visualize the internal structure of the cell while SEM doesn’t require this

Question 29

Contrast TEM and SEM in terms of dimensions of images produced, resolution and the amount of sample that can be analyzed at a given time

Answer 29

Dimensions- TEM provides a 2D image while SEM provides a 3 D image Resolution- TEM has a much higher resolution while SEM has a lower resolution Amount of sample analyzed- SEM allows for large amount of sample to be analyzed at a time whereas the TEM only small amount of sample can be analyzed at a time

Question 30

What are the key uses of transmission electron microscopes?

Answer 30

Uses electron beams that pass through a specimen to visualize small images; useful to observe small, thin specimens like tissue sections and sub cellular structures

Question 31

What are the key uses of scanning electron microscopes?

Answer 31

Uses electron beams to visualize surfaces; useful to observe the three-dimensional surface details of specimens