In Transmission Electron Microscope (TEM), a beam of electrons interact with the specimen to form image as
In Transmission Electron Microscope (TEM), a beam of electrons interact with the specimen to form image as
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Correct Answer: Option A
Explanation
In TEM, a focused beam of high-energy electrons (typically 60–300 keV) is transmitted through an ultra-thin specimen (50–100 nm). Electrons interact with the specimen: areas of high electron density (heavy metal stains, dense organelles) scatter electrons strongly and appear DARK; electron-lucent areas transmit more electrons and appear LIGHT. The transmitted electron beam is focused by electromagnetic lenses onto a fluorescent screen or CCD detector. The image is essentially a two-dimensional shadow/projection of the specimen's density variations. This is different from SEM (which uses reflected/secondary electrons to give surface topology images) and different from diffraction patterns.