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| Q. |
Which of the following are true for electron microscopy? |
| A. | specimen should be thin and dry |
| B. | image is obtained on a phosphorescent screen |
| C. | electron beam must pass through evacuated chamber |
| D. | specimen should be thin and dry, image is obtained on a phosphorescent screen and electron beam must pass through evacuated chamber |
| Answer» D. specimen should be thin and dry, image is obtained on a phosphorescent screen and electron beam must pass through evacuated chamber | |
| Explanation: since electrons can travel only in high vacuum, the entire electron path through the instrument must be evacuated; specimens must be completely dehydrated prior to examination. only very thin specimens can be observed in the conventional electron microscope since the penetrating power of electrons through matter is weak. the magnified image may be viewed on a phosphorescent or fluorescent screen. | |
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