Question

question 5 of 10
which type of scanner uses x - rays, and why?
a. bar - code scanners, because x - rays produce a pattern of reflected light when they shine on a pattern of black - and - white images
b. computer scanners, because x - rays release electrons via the photoelectric effect
c. security baggage scanners, because x - rays either pass through or are absorbed by the objects in the baggage, creating an image of the objects
d. bar - code scanners, because x - rays are low - energy waves, making it safe for the machine operators

Explanation:

Bar - code scanners use visible light (not X - rays) to read barcodes. Computer scanners also use light (usually visible light) to create digital images of documents etc. X - rays are used in security baggage scanners. X - rays have properties that allow them to penetrate some materials (pass through) and be absorbed by others. The differential absorption and passage of X - rays through different objects in the baggage create an image (similar to medical X - rays which create images of bones and soft tissues based on X - ray absorption). X - rays are not low - energy waves (they are high - energy electromagnetic waves). And the reason for using X - rays in security scanners is their ability to create an internal image of the contents of the baggage based on absorption and passage through objects, not because of the photoelectric effect (which is relevant in some other contexts like in the operation of some light - sensitive devices but not in the way described for computer scanners in option B).

Answer:

C. Security baggage scanners, because X - rays either pass through or are absorbed by the objects in the baggage, creating an image of the objects