Lab- Microscopes Flashcards
What is magnification ?
Enlargement of object
What is resolution?
Degree to which detail is maintained in magnified image
What is resolving power?
Minimum spacing between 2 points where can be clearly seen as separate entities
What is the light source of a Brightfield microscope?
Visible light
What is the light source of a Darkfield microscope?
Visible light
What is the light source of a Fluorescence microscope?
UV light
What is the light source of a Transmission Electron Microscope ( TEM)?
Electrons
What is the light source of Scanning Electron Microscope?
Electrons
What is the magnification of a Brightfield Microscope?
1500x
What is the magnification of a Darkfield Midroscope?
1500x
What is the magnification of a Fluorescence microscope?
1500x
What is the magnification of a Transmission Electron Microscope?
500,000 -1,000,000x
What is the magnification of a Scanning Electron Microscope?
10,000- 1,000,000x
What is the wavelength of visible light?
550nm
What is the wavelength of UV light?
100- 400nm
What is the wavelength of light produced by electrons?
0.005 nm
What is the limit of resolution of visible light?
220nm
What is the limit of resolution of UV light?
110nm
What is the limit of resolution of electrons?
0.2 nm
What is the relation between limit of resolution and magnification capability ?
As the limit of resolution becomes smaller, the magnif8dation capability increases
What is the conventional technique of microscopy?
Brightfield Microscopy
When Brightfield Microscopy suitable?
Suitable fir observing the natural colors of a specimen or the observation of stained samples
How do colors contrast in Brightfield microscopy?
The specimen appears darker on a bright background
Why are stains used in Brightfield Microscopy?
Stains used to aid in increasing the contrast of cells so they are more easily visible
Describe how images appear in Darkfield Microscopy
Specimens appear bright on a dark background
Specimens appear bright, because they reflect the light from the microscope into the objective
When is Phase Contrast Microscopy used and why?
- 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
How does Phase Contrast Microscope work?
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
Give the 3 differences of SEM and TEM based on cellular composition, electrons and observed samples
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
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
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
What are the key uses of transmission electron microscopes?
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
What are the key uses of scanning electron microscopes?
Uses electron beams to visualize surfaces; useful to observe the three-dimensional surface details of specimens
