3.1,3.2 : mircoscopes Flashcards
magnification equation
size of image/ size of real object
Magnification
How much larger the image is than the specimen
Resolution
How well a microscope distinguishes between 2 separate points that are close together
Two main types of microscope
optical and electron
Optical microscopes
Use light to form an image
can’t view organelles smaller than 0.2 micrometers
smaller magnification than electron microscopes
2 types of electron microscope
Scanning electron microscope (SEM)
Transmission electron microscope (TEM)
Transmission electron microscope
Use electromagnets to focus a beam of electrons which are transmitted through the specimen
Transmission electron microscope
image
denser parts of specimen absorb more electrons = darker
high resolution images = see internal structure of organelles
Transmission electron microscope
disadvantages
only used on thin specimens
Scanning electron microscope
Scan a beam of electrons across the specimen which knocks electrons off specimen which are gathered in a cathode ray tube = image
Scanning electron microscope
image
show surface of specimen
3D
can be used on thick specimen
Scanning electron microscope
disadvantages
give a lower resolution than TEMs
