Final answer:
Metal is vaporized during shadow casting and coats the specimen surface facing away from the filament. For SEM preparations, sputter-coating is required whereas TEM preparations do not necessarily involve coating, indicating that specimen preparation can differ significantly between SEM and TEM.optio c is correct.
Step-by-step explanation:
When preparing specimens for shadow casting in electron microscopy, the surfaces that get coated with metal are those that are facing away from the filament. During the shadow casting process, metal is vaporized in a vacuum chamber, and it travels in a straight line from the source (the filament) until it deposits on the surface of the specimen. Since the metal vapor cannot bend around obstacles, it coats the surface that is exposed to it, which is the side facing away from the source of the metal vapor (the filament). Thus, the correct answer to the question is (C) those facing away from the filament.
In reference to question 11, which asks about the differences in specimen preparation for TEM and SEM, the correct answer is (B) Only the SEM specimen requires sputter-coating. This is because the SEM uses electrons scanning the surface of the specimen, where a conductive coating is necessary to prevent charging, whereas TEMs transmit electrons through the specimen, which often requires that the specimen be thin and not necessarily coated.