Question

question 6 (4 points) (02 02 mc) which of the following best explains how a scanning electron microscope is used to produce an image of a specimen? a an electron beam strikes the specimen, is absorbed by the specimen, and is used to produce an electrically charged image on a screen b an electron beam passes over the specimens surface and displaces electrons, which are then focused on a screen to form an image c an electron beam traces an outline of the specimen onto a screen, and reflected electrons are collected to form the rest of the image d an electron beam travels through the specimen, and as it does so it burns an image of the specimen on a screen

Explanation:

In a scanning electron microscope (SEM), an electron beam scans over the specimen's surface. This causes electrons to be displaced from the specimen. These secondary electrons are then focused on a screen to form an image. Option b describes this process correctly. Option a is incorrect as the electron beam is not absorbed to produce a charged - image in this way. Option c is wrong because the electron beam does not trace an outline first. Option d describes the principle of a transmission electron microscope (TEM) rather than an SEM.

Answer:

B. An electron beam passes over the specimen's surface and displaces electrons, which are then focused on a screen to form an image.