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

Regions with higher electron density in a transmission electron microscope scatter more electrons and appear darker on the image.

Step-by-step explanation:

In a transmission electron microscope (TEM), areas of a specimen that have higher electron density scatter more electrons compared to areas with lower electron density. This increased scattering causes these regions to appear darker on the TEM image. This is because the dense regions absorb more electrons, preventing them from reaching the projection screen, resulting in a darker appearance. Conversely, regions of a specimen with lower electron density scatter fewer electrons and therefore appear lighter on the image. So, the correct answer to the question is 2) more; darker.