Briefly explain how a scanning electron microscope (SEM) produces an image
What will be an ideal response?
In the SEM, a hot tungsten filament emits a beam of electrons, which is focused by electromagnets onto the surface of the specimen. This primary electron beam causes the elements that make up the upper layers of the specimen to emit electrons known as secondary electrons. About 20–30 percent of the primary electrons rebound off the surface of the specimen. These electrons are known as backscattered electrons. The emitted electrons (both secondary and backscattered) are collected, and the amplified signal is displayed on a cathode-ray or TV tube. By scanning the primary electron beam across the specimen's surface in synchronization with the cathode-ray tube, the SEM converts the emitted electrons into an image of the specimen that is displayed on the cathode-ray tube.
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Crime is lower in those communities where the police patrol on foot is an example of a ______.
A. assertion B. hypothesis C. research question D. research statement
Which of the following is NOT an advantage of open institutions?
A. They relieve the problem of overcrowding in other types of institutions. B. They ensure regulation and regimentation. C. They avoid many of the negative aspects of traditional total institutions. D. They have economic and community service advantages.
Banks have been pressured by government officials to improve their password protection for online banking
Indicate whether the statement is true or false
It is not a violation of federal law to use a public telephone to access without authorization any data processing system involved in interstate commerce
Indicate whether the statement is true or false