How much would you have to zoom in on a map of the United States to replicate the power of an electron microscope?

• A. 100,000,000
• B. 1,000
• C. 10,000
• D. 1,000,000

Answer: (A)

The idea here is about scale and magnification. Electron microscopes work because electrons have wavelengths much shorter than visible light, giving them the ability to resolve features on the order of a few tenths of a nanometer—atoms and their arrangement. To imagine doing the same thing with a map of the United States, you’d have to magnify the map so far that features that are far apart on the real world (hundreds or thousands of kilometers between cities) would be represented on a display at atomic-sized scales. That requires an enormous zoom—about 100 million times. Other magnifications (thousands, ten thousands, or even a million) are far too small to bridge the gap from city-scale distances on a map to atomic-scale detail. So, the large magnification of roughly 100 million times reflects how much bigger the image would have to be to mimic electron-m microscope-level resolution on a macroscopic map.