INTRODUCTION
MICROSCOPE PARTS MAGNIFICATION RESOLUTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The specimen must be dead
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Electromagnets are used
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Thin slices must be used
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Air will scatter and interfere with the passage of electrons
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Detailed explanation-1: -Most electron microscopes are high-vacuum instruments. Vacuums are needed to prevent electrical discharge in the gun assembly (arcing), and to allow the electrons to travel within the instrument unimpeded.
Detailed explanation-2: -The vacuum inside an electron microscope is important for its function. Without a vacuum, electrons being aimed at the sample would be deflected (knocked off course) when they hit air particles. But liquid water, which is abundant in biological samples, evaporates immediately in a vacuum.
Detailed explanation-3: -Electron microscopes use a beam of electrons rather than visible light to illuminate the sample. They focus the electron beam using electromagnetic coils instead of glass lenses (as a light microscope does) because electrons can’t pass through glass.
Detailed explanation-4: -Besides protecting the electron source from being contaminated, vacuum also allows the user to acquire a high-resolution image. In the absence of vacuum, other atoms and molecules can be present in the column. Their interaction with electrons causes the electron beam to deflect and reduces the image quality.