Question

Regions of a specimen with higher electron density scatter ___________ electrons and, therefore, appear __________ in the image projected onto the screen of a transmission electron microscope.

1) more; lighter
2) more; darker
3) fewer; darker
4) fewer; lighter

Answer 1

In a transmission electron microscope, regions with higher electron density scatter more electrons and appear darker in the projected image. This is because they allow fewer electrons to pass through to the detector.

Step-by-step explanation:

Regions of a specimen with higher electron density scatter more electrons and, therefore, appear darker in the image projected onto the screen of a transmission electron microscope. The correct answer is option 2) more; darker.

This happens because in transmission electron microscopy, the electron beam penetrates the specimen. Areas that are electron-dense, meaning they have more atoms to scatter the electron beam, will scatter more electrons away from the detector. As a result, these areas let fewer electrons through to the screen, hence they appear darker compared to regions with lower electron density, which scatter fewer electrons and thus appear lighter on the screen.