1.1 World Of The Microscope Flashcards
magnification
The number of times bigger the image looks compared to the real object
image
what you see when you look through the microscope; the image of the real object appears magnified
real object
the specimen you put under the microscope
magnification =
magnification = size of image/ size of real object
size of image =
magnification x size of real object
size of real object =
size of image/ magnification
Resolving power
The measure of the ability to distinguish two separate points that are very close together
How does a light microscope work and what is its maximum magnification?
Uses a beam of light to form an image of an object and can magnify up to 2000 times
What are some advantages of the light microscope?
Relatively cheap
Easy to use
Can be used almost anywhere
Can magnify live specimens
What are some disadvantages of the light microscope?
Magnification isn’t very high: you can see cells and some structures but not the details of organelles
When was the electron microscope invented?
In the 1930s
How does an electron microscope work and what is the maximum magnification?
Electron microscopes use a beam of electrons to form an image and can magnify and object up to around 2,000,000 times
What are some advantages of the electron microscope?
- Scanning electron microscope can create dramatic 3d images
- Transmission electron microscope has very high magnification
What are some disadvantages of the electron microscope?
- Very expensive
- Hard to use
- Has to be kept in temperature, pressure and humidity-controlled room
- Can’t magnify live specimens (specimen has to be kept in a vacuum)
What is the difference between magnification and resolution?
Magnification refers to the degree of enlargement of an object. Resolution is the ability to distinguish between 2 points in an object, showing how clear and sharp the image is.
Compare and contrast the magnification and resolution obtained by using light and electron microscopes.
Light microscopes use visible light and have lower magnification and resolution compared to electron microscopes, which use electron beams. Electron microscopes provide higher magnification and resolution, allowing for detailed imaging of smaller structures compared to light microscopes.
Evaluate the use of an electron microscope and a light microscope, giving one example where each type of microscope might be used.
Electron microscopes
magnify up to around ×2 000 000
have a resolving power of about 10 nm (scanning electron microscope) or 0.2 nm (transmission electron microscope)
may be used to examine subcellular structures (e.g., chromosomes during cell division)
light microscopes
magnify up to around ×2 000
have a resolving power of about 200 nm
may be used to look at cells dividing (e.g., stained onion cells)
Explain the importance of microscopes in the development of our understanding in cell biology
Without microscopes we cannot see most cells.
Light microscopes
- show cellular structure of living organisms and some subcellular structures (e.g., nucleus and chloroplasts)
- allow observation of living cells and staining of cells to show different features
Electron microscopes
-enable examination of cells in great detail
- help determine what goes on within individual body cells
- can only be used for dead specimens in a vacuum
When we’re the fist light microscopes developed?
Mid 17th century
Why would you have to change the objective lens to its lowest
Easier to focus and gives largest field of view
How could you adjust a microscope to see an object more clearly?
TURN the fine focus knob
What is the magnification and resolving power of a light microscope?
Magnification: x2000
Resolving power: 200nm
What is the magnification and resolving power of an electron microscope?
Magnification: x2,000,000
Resolving power: 10nm(SEM), 0.2nm (TEM)
