Microscopes Flashcards
What is the Resolution and Magnification of a light microscope?
Resolution- 200nm
Magnification - 1500x
What is the Resolution and Magnification of a TEM?
Resolution- 0.1nm
Magnification - 500,000x
What is the Resolution and Magnification of a SEM?
Resolution- 0.1nm
Magnification - 50,000
How does a light microscope work?
It uses lenses and a beam of light is passed through a specimen.
How does a TEM work?
Uses electromagnets focus a beam of electrons. Denser parts absorb more maker the image darker.
How does a SEM work?
An electron beam is scanned across the specimen. The electrons don’t pass through the specimen they bounce off and are detected by detectors.
What are the Adv of a SEM?
- Has a very good resolution
- Can produce detailed images on structure inside the cell
- Produces a 3D image
What are the DisAdv of a SEM?
- Electrons are deflected by air so has to be in a vacuum so the specimen is not living
- Very Expensive
- Preparing samples require a high level of training
What is the difference between magnification and resolution?
Magnification is the number of times larger an image appear compared with the size of an object. Resolution is the ability to distinguish between 2 separate points that are close together to see a clear image in detail. The higher the resolution the greater the detail you can see.
What is the maximum magnification and resolution of a LSC?
Magnification - 20,000x
Resolution - 20nm
What is the need for staining?
Staining is used to show contrast in cells and to be able to differentiate between different organelles
How are EM specimens prepared?
- They are dehydrated so the EB is not affected by evaporating moisture
- Coated with a heavy metal to scatter electrons and create contrast.
What is the equation to calculate Magnification?
Magnification = Image/Actual
