Microscopes Flashcards
What is magnification?
The process of enlarging the physical appearance/ image of something.
How do you work out total magnification?
Eye piece lens magnification and the objective lens magnification.
What is resolution?
The ability to distinguish between two points as separate structures.
What are the steps to prep a microscope slide?
- Sample is thinly sliced.
- Add a drop of water
- Stain is applied.
- Cover slip is added at an angle.
Why does a sample for a light microscope have to be thinly sliced?
To let light pass through to see all the internal structures.
What are some limitations of a light microscope?
-Visibility is limited as it has a low resolution.
-Fixed and short wavelength so also gives it a low resolution.
-Lower magnification.
What are some advantages to an electron microscope?
-Shorter wavelength so higher resolution.
-Higher magnification.
What are the two types of electron microscopes?
-Scanning electron microscope.
-Transmission electron microscope.
What are some advantages of a light microscope?
-Can use coloured dies to give a coloured image.
-Can look at living cells and their processes.
-Not many artefacts.
What are some limitations of an electron microscope?
-Image is not coloured.
-Cannot look at living cells.
-Sample prep is complicated and produces more artefacts.
What does a scanning electron microscope do?
-Electron beam bounces off surface so produces 3D image of surface.
What is an advantage and disadvantage of a SEM?
Advantage- sample does not need to be thin.
Disadvantage- Lower magnification and resolution compared to TEM.
What does a transmission electron microscope do?
-Electron beam penetrates sample so can show internal structures of organelles.
What is an advantage and disadvantage of using a TEM?
Advantage- very high magnification and resolution.
Disadvantage- sample needs to be extremely thin.
What is the equation for magnifiction?
M=Image size/ Actual size.
