Questions: Which microscope part is used in both the electron microscope and the light microscope?

The answer is the first one: Specimen stage.

Explanation for each option:

1. Specimen stage: This is the correct answer. Both electron microscopes and light microscopes have a specimen stage where the sample is placed for observation. It is a fundamental component in both types of microscopes, allowing the specimen to be positioned and held steady during examination.

2. Light beam: This is incorrect. A light beam is used in light microscopes to illuminate the specimen, but electron microscopes use an electron beam instead of light.

3. Magnets: This is incorrect. Magnets are used in electron microscopes to focus the electron beam, but they are not used in light microscopes.

4. Fluorescent screen: This is incorrect. A fluorescent screen is used in electron microscopes to detect electrons and form an image, but it is not a component of light microscopes.

5. Electron beam: This is incorrect. An electron beam is specific to electron microscopes and is not used in light microscopes.

In summary, the specimen stage is the part that is common to both electron and light microscopes.