Electron Microscopes Flashcards
Why do electron microscopes have a higher resolution than light microscopes?
They use electrons rather than light to form an image which have a shorter wavelength than light.
What are limitations of electron microscopes?
Expensive and only produce black and white images.
How does a Transmission Electron Microscope work?
Use electromagnets to transmit a beam of electrons through a specimen. The denser parts absorb more electrons, so appear darker in the image formed.
Advantage of TEMs
Produce high-resolution images, meaning they can be used to observe the internal structures of organelles
Limitation of TEMs
Specimen must be viewed in a vacuum, meaning only non-living or dead organisms can be observed. Specimen must be thin to allow electrons to pass through.
What is the resolution of TEMs?
Maximum of around 0.5 nm.
What is the magnification of TEMs?
Maximum of around x 1,500,000.
How does a Scanning Electron Microscope work?
Scan a beam of electrons across the surface of a specimen. Reflected electrons are then used to form an image.
Advantage of SEMs
Produce 3D images of the surface of the specimen.
Limitation of SEMs
Only view non-living or dead specimens.
What is the resolution of SEMs?
Maximum of around 5 nm.
What is the magnification of SEMs?
Maximum of around x 1,500,000.
