Prescott's Microbiology 8th Edition by Joanne Willey, Linda Sherwood, Christopher J. Woolverton, Lansing Prescott, John Harley, Donald Klein

Exercise 5

How does the scanning electron microscope operate, and in what way does its function differ from that of the TEM? The SEM is used to study which aspects of morphology?

Step 1 of 3

A scanning electron microscope (SEM) generates images by hitting the specimen with an electron beam and collecting the electrons that get bounced back from the specimen. The amount of electrons that get reflected (called secondary electrons) is increased when the electron beam hits a raised area on the surface.

Dips in the surface decrease the amount of secondary electrons generated. Lighter areas on the image are where the surface of specimen is higher and darker areas are where the specimen surface drops.