Microscopy Flashcards
What is a TEM
Transmission Electron Microscope
What is a SEM
Scanning Electron Microscope
What is Resolution
The minimum distance apart 2 objects can be in order to be distinguishable
Equation for Magnification
I = AM
I = Image size
A = Actual size
M= Magnification
Why do Light microscopes have a weaker resolving power than electron?
They have a longer wavelength
Why do Electron Microscopes have a High resolving power
Short Wavelength
How do TEM microscopes work
Electron beams are shot through a thin layer of specimen from underneath , produces black and white image
How are electron microscopes focused
Electromagnets
What electron microscope has a higher resolving power?
Transmission electron microscope
What are the resolving powers of the microscopes?
Light - 0.2 micrometers
TEM - 0.1nm
SEM - 20nm
Limitation of Electron microscopes
Specimen must be in vacuum, living cannot be observed
Complex staining process
Specimens must be thin (only for TEM)
Image could contain artefacts, misleading
How does the SEM work
Electrons deflect off specimen
Why can’t a resolving power of 0.1nm be always reached?
High energy of electrons may destroy specimen
